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Sika Facade Systems

Sealing and Bonding in Facades –A Specification Guide

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Customer ServiceSika Engineering Silicones Srl.Via L. Einaudi, 6I-20068 Peschiera Borromeo (MI)Phone +39 02 516591 205Fax +39 02 516591 [email protected]

www.sika.com

Our most current General Sales Conditions shall apply. Pleaseconsult the Product Data Sheet prior to any use and processing.

Sika® Facade Systems

Sealing and Bonding in Facades – A Specification Guide

Technical ServiceSika Services AG Facade Competence CentreTüffenwies 16CH-8048 ZürichPhone +41 56 648 5287Fax +41 56 648 [email protected]

Sika is a globally active company in the speciality and construction chemicals business. It has subsidiary manufacturing,sales and technical support facilities in over 70 countries around the world.

Sika is THE global market and technologyleader in waterproofing, sealing, bonding,dampening, strengthening and protection of buildings and civil engineering structures.

Sika has more than 11’000 employeesworldwide and is therefore ideally positionedto support the success of its customers.

Sika – Your Local Partner with a Global Presence

Facades by (Project No): Josef Gartner GmbH (3, 5, 13, 14, 18, 21, 27); Schmidlin AG (1, 2, 17, 22, 23); Yuanda (6, 8, 19); Cuhadaroglu (11, 20, 26); Mero (4, 25); Alico (7); Compact Metal (9); Inasus (12); Vitro Cristalglass (16); Photos by: Gardin & Mazzoli (14, 18); Daniele Domenicali (Front, 3); Guy Nowell (13); Beyond Architecture Cultural Development Co Ltd, Mr. Zhou Li (21); Schmidlin AG (1, 2, 17, 22, 23);

Contents

1

Introduction

High-tech facades 5

Glazing Technologies

Four-sided structural glazing 6Two-sided structural glazing 6Bolt-fixed glazing 7Total vision glazing 7

Structural Glazing SG

SG modular design 8Joint design and calculation 10Support beyond formulas 14Facade system components – Glass and Metal 15SG silicone adhesive sealants 16

Insulating Glazing IG

IG modular design 18Seal height calculations 20IG secondary sealants 22Gas-filled IG units 23

Weathersealing WS

Joint design 24WS silicone sealants 24Natural stone sealants 26Total vision glazing 28Fire-rated sealing 29

Vapour Proofing

Facade membrane systems 30

Ancillary Products

Surface treatment 32Cleaner, primer 32Spacer tapes 33

Facade Competence Centres FCC

Project service 34Comprehensive quality management 35Project testing 36Project procedure: workflow 37Technical glossary 38

Peek & Cloppenburg Store, Cologne, Germany,Renzo Piano Building Workshop

Architecture thrives on change. On creative ideas and bold solutions that fas-cinate and surprise us everytime. Curtain walls are aparticularly severe challengefor planners, because they not only set the character ofthe structure but must alsomeet stringent requirements.

Creative Facade Architecture

To strike the ideal balance between aes-thetic appeal and energy efficiency, archi-tects are increasingly turning to glass forcurtain wall construction. As transparentstructural glazing walls, single or doubleglazed or even double skin facades. Glasscan also be combined with other materialssuch as natural stone, metals or plasticcoated metals, giving planners a widescope for creativity.

But an immaculate optical appearanceisn’t the only crucial factor. Facades andwindows must provide long-term durablesystems. This requires perfect adhesionbetween the components and highly elastic, weatherproof seals. These speci-fications call for high-tech silicone seal-ants, which are tailored to meet highlyspecific demands and guarantee peak performance in every respect.

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High-tech Solutions for perfect Facades

With this application in mind, Sika supplies a wide range of tried-and-tested, inno-vative facade products for every demand:

Sikasil®. Each of these sealants and adhesives has highly specific properties that are precisely tailored to the particularapplication. From structural glazing andinsulating glass secondary seals throughto weatherseals.

SikaMembran® membrane systems supplement ideally the sealants range for water/vapour proofing wide joints in bothcurtain wall and ventilated facades.

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Projects on this page:1 Peek & Cloppenburg Store, Cologne, Germany2 30 St. Mary Axe, London, UK 3 Zhang Jiang Hi-Tec Park, Shanghai, China4 New Exhibition Center Milan, Italy5 University of Chicago, USA6 Jiangsu Telecom Building, Nanjing, China7 Crystal Tower, Manama, Bahrain8 Russia Federation Tower, Moscow, Russia9 One Marina Boulevard (NTUC Building), Singapore

Front page:Drugstore Publicis, Paris, France

Sika’s Sealing and Bonding Solutions – for Facades in every Climate

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Optimum Safety

Mechanical FixingIn the two-sided structural glazing system,only two mutually opposite glass or paneledges are bonded (horizontally or vertically)to a frame with Sikasil® silicone adhesive.The two other mutually opposite sides arefixed mechanically like capped CW systems.

Mechanical fixing of the glass element at twosides does not affect the loads on the twobonded sides. Since excessive bending ofthe glass must be prevented, the minimumdimensions of the joint must not be changedcompared to a four-sided system.

Advantages of this SystemHigh mechanical safetyThe silicone adhesive and the mechanical fasteners help distribute the dynamic forcesMetal cap profiles can be used as design elements to make the facade seem less severe

Frameless Appearance

Impressive Glass HeightsTotal vision glazing (fin glazing) impressesby its even frameless appearanceand the huge glass sizes.

Total vision glazing resembles two-sidedstructural glazing where the top and bottomglass edges are embedded in the ceilingand floor slab. The vertical glass edges arestructurally bonded to the glass fins.

Advantages of this SystemAttractive appearance without visibleframesThanks to its high elasticity, the siliconesealant can transmit the loads more efficiently and uniformlyTemperature distribution in the glass isideal, since there are no cap profiles,which would act as shades. This reducesthe risk of glass breakage caused by thermal stresses

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dynamic loads are transmitted through thesilicone adhesive. To support the dead loadof the glass, we recommend a mechanicalsupport that is not visible from the outside.

Advantages of this SystemAttractive appearance without visibleframesThanks to its high elasticity, the siliconesealant can transmit the loads at all foursides more efficiently and uniformlyTemperature distribution in the glass isideal, since there are no cap profiles,which would act as shades. This reducesthe risk of glass breakage caused by thermal stressesThe facade is more energy-efficient asthere are no external metal parts and alljoints are sealedGreater self-cleaning from level glass surface

Optimum Transparency

Structural glazing systems can be either two-sided or four-sided, with each design having its own particularadvantages. In general, for efficient and energy-saving building manage-ment, double glazing is recommended.

Frameless AppearanceFour-sided structural glazing is impressivefirst and foremost because of its monolith-ic frameless appearance. All four sides ofthe large-format pane element are bondedto an adapter frame with Sikasil® SGsilicone adhesive sealants and have novisible frame. These prefabricated glassmodules are subsequently attached to thesupport structure so that the facade givesthe appearance of a flat glass surface. The

Four-sided Structural Glazing

Two-sided Structural Glazing

Total Vision GlazingBolt-fixed Glazing

For the appropriate fin glazing silicone sealants Sikasil® SG and Sikasil® WS see page 28.For structural glazing silicone adhesive sealants Sikasil® SG see page 16. For UV-resistant weather sealing between the glass panes with Sikasil® WSsilicones see page 24.

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The Lightness of Glazing

Mechanical FixingIn bolt-fixed glazing systems, the glass elements are fixed to cable systems or metal beams by metal fasteners. These fasteners are embedded in holes in theglass pane with “glass cement”.The glasses can be single panes (e.g. laminated glass in the outer skin of the double skin facade) or insulating unitswith UV-resistant silicone edge sealing andeven with argon filling (Sikasil® IG).

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Advantages of this SystemHigh mechanical safetyLightweight glass constructions feasible

For the embedding of the metal fasteners into the glass holes and perfect levelling of production tolerances please ask for theSika® AnchorFix® series.

Integrated Systems

A fully integrated structural glazing systemis only possible if a number of conditionsare met:Project-specific computation of the jointdimensions so that the system can be perfectly executed down to the last detailFactory bonding of the industriallymanufactured glass modules with extremepositional accuracyFrame construction exactly tailored to thetype of facadeSealants and weatherseal gaskets of high-quality silicones, which meet thestrictest construction regulations and international standardsStringent quality control on all the products used, from production through to application

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Zorlu Plaza, Istanbul, Turkey

Structural glazing modules are subject to extremely highstresses. They must accom-modate wind and snow loadsas well as thermal expansion,and permanently transfer theforces to the support struc-ture, while also withstandingweathering over many years.

Specialized Products

High-modulus Sikasil® SG silicone adhesive sealants offer the best propertiesfor this purpose. Sika’s low-modulusSikasil® WS weatherseals accommo-date the movements between the struc-tural glazing modules and durably sealthem against wind and weather. The elasticseal can even reduce damage in small to medium-scale earthquakes and bombblasts.

Structural Glazing – sophisticated Architecture and innovative Technology

The illustration shows a structuralglazing module prototype. This diagramis not intended as a construction guide.More elaborate, additional structuralelements may be needed to satisfynational construction regulations orproject-specific requirements.

Adapter frame

Weatherseal

Setting block

Mechanical support

Backing material

Structural glazing joint

Spacer tape

Stepped insulating glass unit

Secondary edge seal

Spacer tape


Setting block

Weatherseal

Symmetrical double glazing unit

Durable Construction

Sikasil® SG silicone adhesive sealantsare used in structural glazing for bondingthe glass elements to the metal supportframes. The elements may be designed assingle glazing or insulating glazing to pro-vide an insulating facade, which forms thecomplete building envelope and guaran-tees excellent corrosion protection. Coated multifunctional insulating glazing providesthe necessary protection against the sun.Other variants include double skin facadesproduced with single glazing elements.The elastic joints produced with Sikasil®

SG silicone adhesives accommodatemovements of the construction elementsresulting from temperature changes, mois-ture, shrinkage of construction materials,sound, wind and vibrations. Permanently.

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Stock Exchange; Johannesburg, South Africa

Economical Construction

Structural glazing facades have both technical and economical advantages:The factory-produced units can be installed quickly and economicallyAn efficient insulating facade slashes thermal losses, providing a much improved energy balanceHigh solar heat recovery can be takeninto account in the energy balanceAcoustic insulation is improved by insu-lating glazing and elastic silicone sealantThese easy to clean facades have lowmaintenance and cleaning costsRepairs can be carried out much moreeconomically by quick and easy moduleexchange

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Airport Barajas Madrid, Spain; Richard Rogers & Estudio Lamela

In structural glazing, the adhe-sive joints should be plannedand arranged according to opti-cal requirements, but theyshould also take into accountdimensional changes in the ad-jacent parts under the effect oftemperature and the movementcapability of the silicone adhe-sive. The joint design thus com-bines shape with functionality.

Joint Design – correct Planning is essential

Calculating the Joint Bite h

Joint bite h as a function of the windload in supported constructions:

h = minimum bite of the adhesive joint (mm)a = length of the short edge of the glass pane or

of the element (mm); with irregularly dimen-sioned glass elements: longest of the shortglass panes1

w = maximum wind load to be received (kN/m2)(100 kp/m2 = 1 kPa = 1 kN/m2)

�dyn = maximum adhesive stress for supported constructions (kPa)Sikasil® SG-500: 140 kPa = 0.14 N/mm2

Sikasil® SG-20: 170 kPa = 0.17 N/mm2

Sikasil® SG-18: 170 kPa = 0.17 N/mm2

1) If the sides of the glass panes are of varying length,then the length of the longest side is used for the calculation.

Joint bite h as a function of the dead load in non-supported constructions:

h = minimum bite of the adhesive joint (mm)G = weight of the glass or of the element (kg)Iv = length of the vertical adhesive bond (m)�stat = permissible stress of the adhesive for

non-supported constructions (kPa)Sikasil® SG-500: 10.5 kPa = 0.0105 N/mm2

Sikasil® SG-20: 12.8 kPa = 0.0128 N/mm2

Sikasil® SG-18: 9.5 kPa = 0.0095 N/mm2

h= a � w2 � �dyn

h= G � 9.81lv � �stat

Example 2 (with Sikasil® SG-500):Pane dimensions: 3 m � 1m � 12 mmDensity of glass: 2.5 kg/dm3

Result: 14 mm

h joint bitee joint thickness

e

h

Seven criteria must be observed:

1. The joint seal must be able to freely accommodate tensile and compressivemovements between the joint edges.Three-sided adhesion of the sealant must be avoided, because it inevitably results in damage to the joint (see fig. on page 13).

2. The joint bite h must not exceed 15 mm for Sikasil® SG-18 andSikasil® SG-20. For bigger joints up to 50 mm, use Sikasil® SG-500.

3. The ratio of joint bite h to joint thicknesse should be at least 1:1 and at most 3:1.

Example 1 (with Sikasil® SG-500):Maximum wind load = 4.0 kN/m2

Pane dimensions: 2.5 m � 1.5 m Result = 21.43 mm The joint bite is thus at least 22 mm.

4. The minimum joint bite is always 6 mm,irrespective of the calculated value.

5. The joint thickness e should be at least6 mm.

6. Always round the result up, never down.

7. The structural joints must not be subjected to external loads as a result offorces such as settlements, shrinkage,creep or permanent stress caused by gaskets etc.

ImportantTypical Stress/Strain Diagram of Sikasil® SG-500

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With all structural glazing constructions,the adhesive bond is subject to consider-able shear movements. The joint thickness(glue line thickness) must therefore be designed so that the movement capabilityis not exceeded.

Criteria for calculating the JointThickness eDimensions of the elementsMaximum temperature differences tobe expectedCoefficients of thermal expansion of thematerials to be bondedEstimated value for joint thickness:half of joint bite, at least 6 mm

Please note that1. All causes of movement must betaken into account:Thermal effects due to different co-efficients of thermal expansion be-tween the glass and the support struc-ture. If the joint dimensions are to bethe same for a complete constructionproject, they must be calculated ac-cording to the dimensions of thelargest paneOther causes, such as shrinkage,subsidence or locally confined stresses

2. Observe all tolerances. These include the tolerances for cutting glass,and/or metal, and installation tole-rances

3. The application temperature must be between +15 °C and +140°C

4. Avoid three-sided adhesion of the sealant so as not to restrict joint movement

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Example 3:Pane dimensions: 2.5 m � 1.5 m(see example 1)Temperature difference aluminium frame: 60 KTemperature difference glass: 30 KMaximum elongation: 12.5% (c = 0.125)Result: e � 6.56 mm

Since the ratio of the joint bite h (22 mm,example 1) to the joint thickness e is supposedto be smaller than 3:1, a joint thickness of atleast 7.33 mm has to be chosen. A standardspacer tape thickness for this would be 8 mm.

Chater House, Hong Kong, China


Glass pane

Adapter frame

1. Deformation of the SG Structure

Calculation of the deformation of the long and shortpanel edges to take account of the different expansionand contraction of glass and adapter frame (thermally induced movements in the shear direction).

�lv, h = change in length (mm)lv = vertical length of the glazing unit (mm)lh = horizontal length of the glazing unit (mm)Tf = average temperature difference of the frame

(approx. 30 – 60 K)Tg = average temperature difference of

the glass (approx. 30 – 60 K)�f = expansion coefficient of the frame material

(aluminium: 23.8 � 10-6 K-1, steel: 12 � 10-6 K-1)�g = expansion coefficient of the glass

9 � 10-6 K-1

2. Total Movements

The calculated deformations of the long and short panel edges yield the total movements according tothe formula above (Pythagoras’ theorem).

�l = total change in lengthv = verticalh = horizontal

3. Calculation of the minimum JointThickness e

Sikasil®SG silicone adhesive sealants are permittedmaximum elongation of 12.5% (c = 0.125). The total of expansion and contraction must not exceed 25%.With these restrictions, the minimum joint depth e can be calculated.

This calculation complies with ASTM C1401.EOTA ETAG No.002 (2004) Annex 2 describes anothercalculation method based on shear modulus.

For support in joint calculations pleasecontact your next Sika Facade CompetenceCentre.

Right joint dimension in its original state Besides tensile movements the adhesive bond also absorbsshear movements in all directions.

e

�Iv,h = Iv,h � [(�f � �Tf) – (�g � �Tg)] �I = �Iv2 ��Ih

2 e � �I

2c �c 2

h

It is essential that bonding on three sides is avoided.

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Calculating the Joint Thickness e

(h= joint bite, e= joint thickness). 13

3. Magnetron Coatings for lowE Glass (soft Coatings)These coatings contain precious metals(such as silver) and are generally not resist-ant enough for use in structural glazingbonds. If necessary, strip off the coatingaround the bond. Adhesion should thereforebe tested on the abraded specimens, sinceabrasion represents a modification of thesurface, and is subject to various parame-ters. Always observe the glass manufactur-er’s instructions.

4. Ceramic CoatingsCeramic coatings are used predominantly in the spandrel area. At the edge regions ofthe glass, they cover colour differences within the insulating glazing edge seal andbetween the edge seal and the structuralglazing adhesive. The adhesive strength ofSikasil®SG silicone adhesives has beenproven in numerous projects and tests ac-cording to the European guideline for bondedglass structures (EOTA ETAG No. 002).

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Glass

1. Uncoated Float GlassFloat glass is generally suitable for all bond-ed glass facades. To reduce the risk of damage from glass breakage, use temperedor laminated glass (with polyvinyl butyralfilm, PVB or casting resins). Sikasil®SGsilicone adhesives ensure excellent adhesionto tempered glass without additional tests.Where laminated glass is used, we recom-mend carrying out compatibility tests.

2. Pyrolytic Coatings for reflective Glass(hard Coatings)Coated glass optimizes the thermal insu-lation of the facade while providing a par-ticularly attractive optical effect. Pyrolyticcoatings (hard coatings) of metal oxidesare ideal for structural glazing, since they resist environmental conditions.For Sikasil®SG silicone adhesives, weonly offer a warranty for adhesion after wehave conducted individual adhesion tests.

Facade System Components – Glass and Metal Frame

However, since the composition of the coatingsmay vary greatly, the warranty requires that individual tests be carried out for each project.

Adapter Frame

The adapter frame is usually made of the following materials:

Anodized aluminiumPowder-coated aluminiumPVDF-coated aluminiumStainless steel

Sikasil®SG silicone adhesives adhere verywell to these materials, but Sika carries outadditional tests to check this separately forevery individual project.Sika® Primer-790 optimizes adhesion oncritical materials.

Support beyond Formulas

Example for FE calculation: L-joints request special care due to high stresses in corners (left). The use of a backer rod reducesthe ultimate stress by more than 30% (right).

Aluminium L-profile

Impact test machine with pendulum (ISO 11343) for velocities of 1.10 m/s – 5.24 m/s at temperatures from–50 to +80°C. As glass deforms with a max. speed of 4 m/s, this is the optimal range for simulating bomb blast tests.

The higher the impact speed, the higher the adhesive’stensile strength, the higher the design factor.

High Speed Tests for Bomb Blast and Hurricane Resistance

For Sika as one of the market leaders in theautomotive and transportation industry highspeed tests are state-of-the-art tests at itshigh-tech laboratories. Before any crash testor bomb blast test we measure high speedimpact on sealants and adhesives on smallspecimens. Based on these values we help to optimize the joint dimensions.

Adhesive joint

Glass pane

Finite Element Calculations

Joint design becomes more complex, jointsizes get smaller and smaller, loads andmovements go to the extremes. Our spe-cialists in the Facade Competence Centrein Switzerland accompany trends and developments not only with sophisticatedtests but also with the latest methods of finite element calculations.

Tensile Shear Strength as a Function of Velocity

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80 and 100 Victoria Street London, UK; EPR Architects

max. stress 1.00 N/mm2

max. stress 1.20 N/mm2 max. stress 0.90 N/mm2

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Structural Bonding

Sika has developed one-part and two-partsilicone adhesive sealants for structuralglazing and insulating glazing applications,and each feature specific advantages.Which of these systems is best for a par-ticular application depends first and fore-most on the specific requirements. Bothsystems offer maximum quality and maxi-mum safety in every respect.

In addition they are characterized by thefollowing special properties:

High tensile strengthHigh tear resistanceHigh elastic recoveryLow volume shrinkage on curing

Sikasil® SG Silicone Adhesives –Systems with individual Advantages

Standards and Guidelines

A wide variety of local standards and guide-lines have become established worldwide.The most important are:

In Europe

EOTA ETAG No. 002-2004: a guideline onthe application and testing of SG adhesives,which is adhered to in most EU states andtakes local regulations into account.

CSTB 3488: describes the French SG regulations for adhesives.

In the USA

ASTM C 1184: a comprehensive SG ad-hesive specification standard.

ASTM C 1401: a guideline for SG appli-cations.

In China

GB 16776-2005: a comprehensive SGadhesive specification standard based onASTM C 1184.

In countries without their own structuralglazing standard, ASTM C 1184 or EOTA ETAG No 002 are usually applicable.

1) Depends on joint dimensions and curing conditions, 2) ISO 868, 3) ISO 8339-A. These figures are intended as a guide and should not be used in preparing specifications.For technical information about the products, please ask for the latest respective data sheets.

Sikasil® SG-18 SG-20 SG-500

Components one-part one-part two-part

Curing system neutral neutral neutral

Processing with guns from cartridges with guns from cartridges machine mixingor foil packs or foil packs

Installation of bonded elements after 2 to 4 weeks1 after 2 to 4 weeks1 after 3 to 5 days1

Maximum of joint bite [mm] 15 15 50

Skin forming time/pot life ~ 30 ~ 15 ~ 60(23˚C/50% rel. humidity) [min]

Permanently elastic range [°C] �40 to �150 �40 to �150 �40 to �150

Shore A hardness2 ~ 44 ~ 39 ~ 45

Tensile strength3 [N/mm2] ~ 1.06 ~ 1.20 ~ 0.95

Modulus at 100% ~ 0.81 (50%) ~ 0.90 (100%) ~ 0.95 (100%)elongation3 [N/mm2]

Elongation at break [%] ~75 ~180 ~100

Design stress in tension [N/mm2] 0.17 0.17 0.14

Pfizer Headquarters, Walton Oaks, Surrey, UK

Peek & Cloppenburg Store, Cologne, Germany,Renzo Piano Building Workshop

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Sikasil® SG-18One-part SG systemNeutral curingReady to processHigh mechanical strengthHigh modulusUV-resistant and weather-resistant

Sikasil® SG-20One-part SG systemNeutral curingOdourlessReady to processExtremely high mechanical strengthcombined with high elasticityUV-resistant and weather-resistant

Sikasil® SG-500Two-part SG systemFor machine applicationNeutral curingFast vulcanization and through-cureExcellent UV and weathering resistanceHigh mechanical strength

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Integrated Systems

In insulating glazing it is particularly impor-tant that no water vapour should penetrateinto the space between the panes, since itwould condense as water on the cold pane.To avoid this during the whole service life ofan IG unit, use a double-sealed edge sealsystem:

Aluminium, stainless steel, or plastic spacers (low thermal conductivity) ensurethe necessary distance between panes.

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Insulating Glazing – keeps Energy Costs low

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�

�

Glass pane SpacerDesiccant

Primary sealant

IG secondary edge seal

Telefónica Headquarters, Madrid, Spain

Thermal Insulation included

The facades are mainly responsible for the ener-gy balance of a building. The excellent thermalinsulating effect of bonded double or tripleglazed units with coated glass can save much ofthe energy otherwise consumed for heating orcooling. The air trapped between the bondedpanes is a poor heat conductor and thereforeforms a good insulating layer between the out-door and indoor air.

The insulating glazing edge seals are predomi-nantly made of bent aluminium or stainless steelspacers filled with a desiccant, thermoplasticpolyisobutylene (PIB) as a primary seal and in-stallation aid, and an elastic sealant as a sec-ondary edge seal. Only high-modulus silicone isapproved as a secondary seal in structural glaz-ing facades. Sikasil® IG silicone sealantswere specifically developed to meet require-ments of insulating glazing and feature specialadvantages:

UV and weathering resistanceDurability Material compatibility

The desiccant (molecular sieve) absorbsany moisture that penetrates through theedge seal.

The polyisobutylene primary seal serves asan installation aid, sealing against moistureand minimizing gas leakage in the case ofinsulating glazing units filled with noblegas (e.g. Argon, Krypton).

The secondary edge sealant bonds thepanes together, provides the double glazingwith mechanical stability, and is also amoisture barrier.

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Fig. 7 Pump action due to climatic loads

Standard external influences

High air pressure,low temperature

Low air pressure,high temperature

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Non-stepped (symmetrical)Double Glazing Units

In the case of double glazing units in me-chanically supported structural glazing con-structions, the outer glass pane is held ontothe frame by means of the secondary edgeseal. The minimum seal height r is calcu-lated for two cases A and B (see formulason the right).

Simple Calculation of the Seal Height in non-stepped Configurations according to EOTA ETAG 002-2004

Silicone Seal Height – detailed Joint Calculation

the glass panes is calculated by variousmethods (e.g. Plate method or Timoschenkomethod). The deflection is influenced by the pane thickness and their size (see Fig. 4 and 5). Small, thick panes re-quire big seal heights (see Fig. 6, e.g. IGU0.75 � 0.75 m: minimum seal height of 18 mm).

3. Real internal PressureThe increase of the cavity volume by theglass deflection reduces the isochoric pres-sure to the real internal pressure. The pumpaction caused by environmental loads isshown in the illustrations in Fig 7.

4. Total Load on the secondary SealThe sum of the climatic load of point 3 and the wind load results in the final loadon the IG edge seal (see Fig. 1 and 2).

Especially for small glass panes and non-standard formats, for a precise calculationof the IG sealant height there are 4 stepsto consider:

1. Calculation of isochoric Pressure p0

The isochoric pressure is a theoreticalpressure caused by climatic loads such asmax. estimated difference of temperature�T and atmospheric pressure �patm andthe difference in altitude � H of productionsite of the IG unit and its installation site.

An average value for p0 of 16 kPa has to beconsidered. For extreme changes of tem-perature or altitude, p0 has to be calculatedwith the formula below.

2. Estimation of Glass DeflectionBased on the value of p0 the deflection of

Calculation of JointDimensions in steppedConfigurations

The IG seal height r for the inside paneis calculated solely by taking the environ-mental loads into account when the smallerinside pane is supported by setting blocks.It is advisable to have the seal heightchecked by one of our Facade CompetenceCentres. r should be at least 6 mm.

Fig. 1 Only climatic loadsare relevant for sealantheight calculation

Fig. 2 Climatic and wind loadare relevant for sealant heightcalculation

A) When the thickness of the outer glass pane � thickness of the inner glass pane:

B) When the thickness of the outer glasspane thickness of the inner glass pane:

r = height of the insulating glasssecondary seal (mm)

a = longest of the short glass edges ofthe project (mm)

w = maximum wind load to be expected(kN/m2)

�ddyynn = permissible adhesive stress for supported constructions; for Sikasil® IG-25:140 kPa = 0.14 N/mm2

Stepped double glazing unit

Symmetrical double glazing unit

IG seal height r

SG joint bite h

SG joint bite hIG seal height r

Stepped Double Glazing Unit

Symmetrical Double Glazing Unit

Fig. 4 Commercial glazing in high-rise buildingsGlass: 6/12/6 mm, p0: 20 kPaSeal height: 6 mm

Fig. 3 Residential fenestrationGlass: 4/12/4 mm, p0: 12 kPaSeal height: 6 mm

Fig. 5 Protective glazingGlass: 10/12/8 + 8 mm, p0: 20 kPaSeal height: 6 mm

Fig. 6 Protective glazingGlass: 10/12/8 + 8 mm, p0: 20 kPaSeal height: 18 mm

r = a � w2 � �ddyynn

p00 = (�T � 0.34 kPa/K ) + �patm+ (�H � 0.012 kPa/m)

Support from our Facade Competence CentresFor precise and reliable calculations ofseal height please contact one of ourFacade Competence Centres.

r = a � w4 � �ddyynn

Important

SG adhesive bonding of an unsup-ported IG unit is not recommendedbecause of excessively high stress in the IG secondary edge.

If inevitable you should contact FCCSwitzerland.

Effect of environmental Loadson Double Glazing Units

Influence of Glass Thickness on Seal Height

The simplified calculations onlyconsider the wind load. EOTA ETAG002-2004 clearly insists on the con-sideration of climatic loads, i.e. forsmall glass sizes and thick glasspanes.

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Highlight Towers, Munich, Germany; Murphy/Jahn

Tailored Properties

The sealant is chosen according to the indi-vidual requirements of the insulating glazingunit. Sika offers Sikasil® IG silicone seal-ants for the secondary edge seals of insu-lating glazing units. These sealants arecharacterized not only by outstanding tool-ing and bonding characteristics, but also by unparalleled UV stability. This permitsdurable constructions with a uniformly highquality of workmanship.

Sikasil® IG secondary Sealants –UV-resistant and extremely durable

Inert Gas Filling

Beside glass coatings the gap-filling withinert gas is one means of reducing heatlosses. With an argon-filled cavity the U-value of an IG unit can be reduced by0.3 W/m2K. This means an oil saving po-tential of up to 3 litres per year per squaremeter of glass facade and even 4 timesmore energy equivalents for cooling in hot climates. For big glass facades thisnot only means a high potential of energysaving but also a tremendous reduction of carbon dioxide and hence the green-house effect.

The high argon diffusion rate of the sili-cones has been the obstacle to the use inargon-filled IG units. Bending movementsof the glass panes due to changes of temperature and atmospheric pressure(page 21, Fig. 6) and the non-elastic behaviour of PIB cause leakage of the primary seal and thus cause high gas lossrates in IG units sealed with silicone.

With the ultra-high-modulus IG siliconesealant Sikasil®IG-25 HM it is pos-sible to produce Argon-filled IG units com-plying with the European standard EN1279part 3 for argon-filled IG units. As the PIBlayer in fact is the argon barrier, compre-hensive application know-how and qualitycontrol during the IG production are crucial. For the stability requested in SGfacades these IG units can be producedwith rigid box-shaped spacer bars (alu-minium or stainless steel). This meant thebreakthrough of argon-filled IG units intothe structural glazing facades as shown in2004 in Helmut Jahn’s Munich HighlightTowers, glazed with 20000 m2 of IG sealedwith Sikasil®IG-25 HM.

For gas-filled IGU in capped curtain wallsystems and conventional window systemsSikaGlaze® IG-50 polyurethane canbe used if the edge seal is not exposed to

UV radiation.

Sikasil® IG-16One-part system, for the secondary edge seal Neutral curingReady to processOutstanding tooling propertiesExcellent weathering and UV resistanceSuitable for stepped double glazingunits in curtain walls

Sikasil® IG-25Two-part secondary edge sealCan be applied by machineOutstanding processing properties(dosing and tooling)High mechanical strengthStructural capabilitiesExcellent weathering and UV resistanceHigh resistance to water and moistureSuitable for all kinds of curtain wall doubleglazing units

Sikasil® IG-25 HMTwo-part silicone secondary edge seal Can be applied by machineOutstanding processing properties(dosing and tooling)Extremely high mechanical strengthExcellent weathering and UV resistanceExtremely high resistance to water andmoistureStructural capabilitiesSuitable for all kinds of curtain wallinsulating glazing units

SikaGlaze® IG-50Two-part polyurethane secondary edge seal Can be applied by machineOutstanding processing properties(dosing and tooling)Very high mechanical strengthHigh resistance to water and moistureSuitable for all kinds of capped curtainwall insulating glazing units

Applicable Standards

The test requirements laid down in inter-national standards are designed to ensurethe insulating glazing unit has a minimum lifetime of 10 years. The climatic test usu-ally includes cyclic conditioning of smalldouble glazing units and subsequent testing of vapour permeability (dew point temperature).

The most important standards are:EN1279, Glass in building – insulatingglass unitsPart 1, generalities, tolerances, system descriptionsPart 2, moisture vapour penetrationPart 3, inert gas leakage ratesPart 4, physical attributes of edge sealsPart 5, evaluation of conformityPart 6, factory production control

ASTM E 773, ASTM E 774

EN13022 and EN15434:Standards for insulating glazing in SG curtain walls.

Sikasil® IG-25 HM and SikaGlaze® IG-50 – Energy-saving with inert Gas Filling

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1) ISO 868, 2) ISO 8339-A, 3) If the IG secondary seal has a structural function, IG-25 has to be used. These figures are intended as a guide and should not be used in preparing specifi-cations. For technical information about the products, please ask for the latest respective data sheets.

Product Name Sikasil® IG-16 Sikasil® IG-25 Sikasil® IG-25 HM SikaGlaze® IG-50

Curing system neutral silicone neutral silicone neutral silicone polyurethane

Components one-part two-part two-part two-part

Processing with guns from cartridges machine mixing machine mixing machine mixingor foil packs

Maximum of seal height [mm] ~15 ~50 ~50 ~50

Applications:

- Standard IG for windows and capped CW systems x x x x

- Symmetrical IG for SG x x

- Stepped IG for SG x3) x x

- IG in two-sided SG x x x

- IG for bolted curtain walls x3) x x

- Gas-filled IGU x x

Skin forming time/pot life(23°C/50% rel. humidity) [min] ~25 ~35 ~110 ~30

Permanently elastic range [°C] – 40 to +150 – 40 to +150 – 40 to +150 – 40 to +90

Shore A hardness 1 ~45 ~45 ~60 ~50

Tensile strength 2 [N/mm2] ~0.87 ~0.90 ~1.12 ~1.5

Modulus at 100% elongation 2 [N/mm2] ~0.83 (50%) ~0.90 ~0.95 (50%) ~0.98

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Weatherseal, double glazing/metal, joint width: depth = 2:1

Perfect Appearance

The quality and optical appearance of acurtain wall are critically dependent onappropriate weather sealing. The individualelements are ultimately subject to extrememovements due to temperature changes,moisture (in the case of concrete), shrink-age of construction materials (wood,concrete), sound, wind and vibrations,which may affect the joints and adjacent elements.

The joints between the elements may beeffectively sealed with preformed gasketsor alternatively with UV and weather resist-ant silicone sealants. Sikasil® WS sili-cone sealants preserve the quality andperfect optical appearance of the facade inthe long term, thanks to their outstandingadvantages:

Sikasil® WS Weatherseals – effective Protection against the Elements

Weathersealing of boltedGlass Facades

To ensure the correct choice of a sealant in bolted glass facades, Sika recommendschecking the design and statics. This isnecessary to ascertain whether the sealantonly serves as a highly elastic weathersealor whether it also acts as a structure-stiffening element, in which case it mustalso be taken into account in the staticcalculations. On request, our FacadeCompetence Centres carry out individualcalculations and tests for each project.

Water/Vapour ProofingMembranes

Connections of the glass facade to theconcrete structure can be too wide for wet sealing. For sound water proofing Sika offers sophisticated vapour control membrane systems (see page 30).

Weatherproofing Gaskets

UV-resistant silicone rubber gaskets aresuitable for use as structural glazingweatherseals. All gaskets (particularly non-silicones such as EPDM) have to beindividually tested for compatibility accord-ing to ASTM C 1087 or EOTA ETAG No. 002.

Sikasil® WS-305 WS-605 S

Components one-part one-part

Curing system neutral neutral

Skin forming time(23°C/50% rel. humidity) [min] ~20 ~25

Permanently elastic range [ °C] – 40 to +150 – 40 to +150

Shore A hardness 1 ~20 ~20

Tensile strength2 [N/mm2] ~0.50 ~0.45

Modulus at 100%elongation 2 [N/mm2] ~0.30 ~0.27

Sikasil® WS-305Ready-to-use one-part sealantNeutral curingUV and weathering resistantHighly flexible

Sikasil® WS-605 SReady-to-use one-part sealantNeutral curingNon-staining on glass and metal surfacesUV and weathering resistantHighly flexible

UV and weathering resistanceImproved impermeability to air anddriving rainVery good movement absorption

Dimensioning of weatherproofing Joints

In generalThe joint edges must run parallel to a depth of twice the joint width, but at least 30 mm. This gives the backing material sufficient gripFor most sealants, the joint width must beat least 4 times the expected joint move-ment, which results from 25% movementcapabilityThe optimal ratio of joint width to depth is2:1 (see Fig. top right)

Project-specific Adhesion Tests

For weather-tight sealing of a curtain wall,it is essential to ensure optimum adhesionof the sealant to the surfaces. Before thesealant is used, it should therefore be individually tested for perfect adhesion to


Because of the requirements for the sealant, standards for weatherseals aresignificantly different from those for structural glazing applications.

ISO 11600ISO 11600 is the world’s first standard to combine the classification of widely different sealant grades and their tests.However, national standards, such asASTM C 920 and DIN 18545 are also important, not only because of local prac-tices, but also because of specific char-acteristics such as the abrasion test (DIN 18545) or early movement capability(DIN 18540).

specimens of the project material at oneof Sika’s Facade Competence Centres.

Individual Colour Scheme

For weatherseals and natural stone seal-ants, Sika offers project-specific colourmatching services. In addition to the widerange of standard colours, Sika also offersindividual special colours on request.Please note that special colours are sub-ject to special delivery conditions such as minimum order quantities and deliverytimes. Your Sika sales manager will bepleased to give you further details.

Double glazing

Metal

Weatherseal

1) ISO 868, 2) ISO 8339-A. These figures are intended as a guide and should not be used in preparing specifica-tions. For technical information about the products, please ask for the latest respective data sheets.

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Telecom Center Munich, Germany; Kiessler + Partner

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Sikasil® WS-355Weatherseal for natural stone facadesReady-to-use one-part sealantNeutral curingNo staining on natural stoneUV and weathering resistantHighly flexible

Applicable Standards

The worldwide most frequently quotedstandard for non-staining sealants isASTM C1248:Standard Test Method for Staining ofPorous Substrates

26 | 27

Sikasil® WS-355

Components one-part

Curing system neutral

Skin forming time(23 °C/ 50% rel. humidity) [min] ~20

Permanently elastic range [ °C] – 40 to +150

Shore A hardness1 ~20

Tensile strength 2 [N/mm2] ~0.47

Modulus at 100%elongation2 [N/mm2] ~0.28

System-compatible Primers

Use Sika® Primer-783 to ensurelong-term adhesion to stones of all types.Exact instructions for applying primer and sealant are given in our applicationguidelines.

Natural Stone Sealing – perfect even in sensitive AreasSealants suitable for naturalStones

Natural stones such as granite, marble andsandstone are highly sensitive materialswhen used on facades. Where an inappro-priate sealant is used, there may be stain-ing of the joint edges or streaking, whichgreatly impairs the optical appearance ofthe facade. Sika therefore recommendsspecial system-compatible Sikasil® WSsilicone sealants ideally suited for use withextremely sensitive natural stone ele-ments, or connecting metal facades andcurtain walls to natural stone elements.

Using the wrong sealants causes staining ofnatural stone elements (see left specimen).

They contain no volatile compounds thatcould migrate into the pores of the naturalstone. We therefore describe them as non-staining. These non-staining siliconesealants are also recommended for glassfacades in order to reduce streaking onglass panes and metal panels and to mini-mize the need to clean the facade.

Double glazing

Natural stone

Non-staining sealant

Important

Since all natural stones are very sensitive materials, a ‘on-staining test’ should be carried out at one of our Facade Competence Centres before any natural stone sealing operation. This is an essential pre-condition for non-staining warranty.

1) ISO 868, 2) ISO 8339-A. These figures are intended as a guide and should not beused in preparing specifications. For technical information about the products, pleaseask for the latest respective data sheets.

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Gansu Province Finance Bureau, Lanzhou, China

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Total Vision Glazing orFin Glazing is similar totwo-sided Structural Glazing

The glass panes reach from head to sillwith tremendous glass sizes. As very highwind loads have to be considered in Asia,where fin glazing is very popular andwidely used for glazing of shop fronts and entrance lobbies, the glass panes are stabilized with glass fins. Sika offers arange of products for sealing the joints,due to the variety of glasses used for finglazing (monolithic, laminated, multipaneinsulating glass).

Total Vision Glazing – perfect Views without Frames

Please note that for durable adhesion of silicones the finish of the glass edge(grinding, polishing, etc.) is crucial.

For support in joint design review,joint size calculation and adhesiontests please contact one of ourFacade Competence Centres.

With Sika’s 2-part polyurethane seriesIcosit®KC the glass panes can be embedded in the floor avoiding any stress concentration and glass cracks.

Fire-rated Sealing

Many casualties have been reported in serious fire catastrophes, not only becauseof fire but of smoke poisoning. The integ-rity of the joints is inevitable and gives firebrigades a chance to rescue people. Sikaoffers 4 hours fire-rated sealants both forvertical joints in facades and for horizontalfloor joints between the facade and thefloor slabs.

Fire-rated Sealing – only the best is good enough

Sikasil® FS-665Weatherseal for fireproof facadesReady-to-use one-part sealantNeutral curingNon-saggingUV and weathering resistantHighly flexibleTested against BS476, part 20:4 hours fire-ratedClassified DIN 4102, B1

Sikasil® FS-665 SLFire-rated, self-levelling sealant forhorizontal jointsReady-to-use one-part sealantNeutral curingSelf-levellingUV and weathering resistantHighly flexibleTested against BS476, part 20:4 hours fire-ratedClassified DIN 4102, B1

Sikasil® FS-665 FS-665 SL

Components one-part one-part, self-levelling

Curing system neutral neutral

Skin forming time(23 °C / 50% rel. humidity) [min] ~15 ~30

Permanently elastic range [°C] –40 to +150 –40 to +150

Shore A hardness1 ~25 ~21

Tensile strength2 [N/mm2] ~0.60 ~0.75

Modulus at 100%elongation2 [N/mm2] ~0.39 ~0.32

1) ISO 868, 2) ISO 8339-A. These figures are intended as a guide and should not be used in preparing specifications.For technical information about the products, please ask for the latest respective data sheets.


A wide variety of local standards and guidelines have become establishedworldwide. The most important are:

In EuropeEN 13501, parts 1– 5, Fire classificationof construction products and buildingelements

BS 476, part 20: Fire resistance tests

DIN 4102: flammability classification

In the USAUL 94

Sikasil® WS-605 SReady-to-use one-part sealantNeutral curingHigh flexibilityUV and weathering resistantAvailable in transparent and other coloursFor laminated and insulating glass

Sikasil® GS-621Ready-to-use one-part sealantAcidic curing (acetic acid)High mechanical strengthUV and weathering resistantAvailable in transparent and other coloursFor monolithic glass

Sikasil® SG-18, SG-20Ready-to-use one-part adhesive sealantNeutral curingVery high mechanical strengthOutstanding UV and weathering resistanceAvailable in blackFor laminated and insulating glass

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Isbank Towers Istanbul, Turkey; Swanke Hayden Connell Architects, Tekeli & Sisa

For fire-rated sealing of indoor joints please ask for Sikacryl® FS-265.It can be overpainted.

CNOOC Building, Beijing, China; Kohn Pedersen Fox Associates PC

20 21

30 | 31

is obviously reversed in tropical regionswith a hot, damp climate outside but withcool, air-conditioned rooms inside.

According to German Standard DIN 4108“Thermal Insulation in Buildings”, a struc-tural element must be designed so that an unacceptable quantity of condensed water is not produced inside the structure;for instance when water vapour diffusesmoving from inside to outside and meets a material with a very high vapour diffu-sion resistance and/or a layer of thermalinsulation.

System Solutions

With SikaMembran® system solutions,facades can be protected effectively andfully in line with their requirements, bothfor curtain walling in glass and for concretestructures.

Water Vapour in Buildings

Along with wind-driven rain, water vapouralone can also become a major problem in the structural framework. If the air iscooled to below the dew point, the excessmoisture condenses as liquid water withinthe structure.

A “moisture transport mechanism” of thiskind where water migrates through struc-tural members in the form of vapour is particularly apparent in climates like that ofWestern and Central Europe and other simi-lar climatic regions in the winter months.There is more water vapour in the atmos-phere in heated rooms than there is in theoutside air, and their difference in concen-tration is balanced by vapour diffusion fromthe inside to the outside. This phenomenon

Vapour Proofing with Membrane Systems

Adia Building, Abu Dhabi, UAE; Kohn Pedersen Fox Associates PC

For wide gaps between the curtain wall and the concrete structure theSikaMembran® membrane system is the best solution.

A secure connection to the structural formwork, yielding durable waterproofing of the joints, is obtained by the quick and easy bonding of the membranes be-tween the envelope fabric and the struc-ture, with the very tolerant and efficientelastic adhesive SikaBond®AT-20 M.

For comprehensive information please ask for our brochure “SikaMembran®

Systems – Membranes for intelligentSealing of Facades”

GLA City Hall, London, UK; Foster & Partners

In ventilated facades the SikaMembran® membraneprovides an adequate vapour barrier throughout thewhole year’s climatic conditions. Water vapour mustnot be trapped in the structure.

Product Overview

22 23

Standard System Self-bonding System (2-sided)

SikaMembran® Outdoor Universal FJ-25 SB2

thickness [mm] 0.6 0.6 0.35

μ-value 52 000 98 000 71000

sd value [m] 30 60 25

System adhesive SikaBond®AT-20 M SikaBond®AT-20 M 2 sides self-bonding

Standard widths of 10/15/20/25/30/35/40/45/50 10/15/20/25/30/35/40/45/50 5.0/7.5/10/1525 m rolls [cm] higher widths on request higher widths on request higher widths on request

Main applications Connecting joints in concrete and brick constructions in ventilated facades Capped system curtain wall

32 | 33

System-oriented Execution

Perfect structural glazing execution requirescareful coordination of details. Sika there-fore offers a wide range of ancillary prod-ucts for preparing substrates and process-ing sealants. These auxiliaries integrate intothe whole facade product system and arecarefully matched to Sikasil® siliconesealants. They will round off your structuralglazing job.

Sika®Ancillary Products –for complete Structural Glazing

Compatible Spacers

Sika® Spacer Tape HD has me-chanical properties perfectly adjusted tomeet the curtain wall requirements. Theyprovide the essential UV resistance anddurability, and are the perfect installationaids for structural glazing elements. Theopen cell structure of the Sika® SpacerTape HD is permeable to air humidityand thus increases the speed of vulcaniza-tion of one-part Sikasil® SG adhesivesealants. These PU foam tapes have beenthoroughly tested for compatibility with allSikasil® silicone sealants, and a warran-ty to this effect is provided.Sika® Spacer Tape HD is availablein the standard thicknesses of 4.8, 6.4,8.0 and 9.5 mm.

Standards

Compatibility tests for sealants with ac-cessory materials are specified in ASTM C1087 and EOTA ETAG No. 002.

Note: Technical information about the products can be found in the data sheetsthat can be obtained on request from oursales offices or from our homepagewww.sika.com.

Pretreatment for optimumAdhesion

Thorough cleaning of the glass and metalsurfaces is essential for reliable bonding ofthe Sikasil® SG silicone adhesivesealants. Therefore Sika supplies specialproducts with optimized adhesion to awide variety of materials. One of ourFacade Competence Centres will carry outthorough tests on the project materials todetermine the best primer to use on themetal frame employed. Based on our ex-perience and the test results, we will makespecific product recommendations foreach structural glazing project.

Glass does not usually needto be primed where Sikasil® silicone products are used.

Surface Treatment Products

Product Application

Sika® Cleaner G+M Cleaner for all types of glass and metalsurfaces

Sika® Cleaner P Cleaner for all types of plastics andpowder-coated metals

Sika® Cleaner-205 Cleaner/activator for anodized aluminium,stainless steel, and many powder coatings

Sika® Primer-783 Primer for porous vitreous surfaces

Sika® Primer-790 Primer for non-porous metal surfacesand powder coatings

Sika® Mixer Cleaner Cleaner for two-part mixing machine

Recommendations for cleaning and priming common Materials

Surface Cleaning agent Priming necessary?

Glass Sika® Cleaner G+M No, but test should be carried out on coatings

Anodized aluminium Sika® Cleaner G+M Not usually, but test Sika® Cleaner-205 should be carried out

Stainless steel Sika® Cleaner-205 Not usually, but testshould be carried out

Powder-coated aluminium Sika® Cleaner P Sika® Primer-790,PVDF-coated aluminium but test should be carried out

New Exhibition Center Milan, Italy;Massimiliano Fuksas4

Facade Competence Centres

R&D has always taken pride of place atSika. At each of our Facade CompetenceCentres in Switzerland and China, we combine R&D with a very special service:individualized structural glazing projectservice and support. This project service isSika’s response to increasing distinctive-ness of the buildings and facade projects.Innovative uses of new silicone sealantsfor facades and windows are in demand;but there is also a growing need for tech-nical support in project planning and exe-cution. At our Facade Competence Centreswe develop new products and processingtechnologies, test known structural glazingmethods, and use the results to optimizeour technical service and project service.

The specialists at our Facade CompetenceCentres provide project service and sup-port for structural glazing projects on allcontinents – from planning through to execution. We place great importance oninterdisciplinary cooperation with our part-ners in the glass industry and with curtainwall manufacturers.

Our Service

Individualized technical service and sup-port with new designsComplete structural glazing system testsincluding joint design, joint dimensioning,adhesion and compatibility tests with original materialsSupport with performing external testsApplicator training at the Facade Compe-tence Centre and in the factory:Production of double glazing units with silicone secondary edge seals, structuralbonding with silicone

Project Service – individual Consultation and Support

Practical assistance with all processingproblems on site by specially trained engineersDevelopment of complete ready-to-install solutions for integrated structuralglazing systems and difficult processingconditionsDevelopment of new products in associa-tion with the customerAfter testing and approval of the project,warranty for the adhesion of Sikasil®

silicone sealants

Sika Facade CompetenceCentres

� FCC Switzerland� FCC China

34 | 35

Systematic Project Workflow

Each structural glazing project is individ-ually tested and approved at one of ourFacade Competence Centres in Switzer-land and China. The customer usuallyreceives design approval and informationfor joint dimensioning within three workingdays and the lab report within the timelisted in the table on page 36. Work canthen begin on bonding the elements.Sika gives a warranty on tested and approved projects.

1. Sealant Tests according to Standardsand GuidelinesSilicone adhesives used for structural glaz-ing must withstand extreme demands ontheir load-bearing capacity and durability.Sika offers one- and two-part systems thatconform to the European guideline forbonded glass structures (EOTA ETAG No.002). The specified tests include, for exam-ple, UV/water immersion at 45 °C for 1000 h and exposure to NaCl/moisture and SO2/moisture. They also comply withAmerican standards ASTM C 920 and C 1135, and Chinese standard GB 16776.

2. Quality Control in Silicone SealantProductionAs a company certified to ISO 9001 andISO 14001, Sika has developed a qualitycontrol system that identifies any deficien-cies at the production stage, and guaran-tees that only perfect goods leave theplant. As a prerequisite for the CE markingSika’s facade silicone production is regu-larly supervised by external auditing insti-tutions.

Recommended Quality Controls during structural Bonding

3. Quality Control in Sealant ApplicationFor every project, it is essential that thecustomer should carry out factory produc-tion controls, with evidence of the mechan-ical strength and adhesion to various substrates (see table above). Precise de-tails on the tests can be found in ourguidelines for structural glazing applica-tion. Sika service laboratories advise cus-tomers as to how to perform best thesecontrols and train staff. Of course the testspecimens can also be sent to our FacadeCompetence Centres for testing and ap-proval. All test specimens must be kept forthe full warranty term.

Important

Sikasil® SG-18, SG-20 and SG-500 should only be used for structural projects if Sika has first given written approval for the particular project.

Sikasil® SG-18, SG-20 Sikasil® SG-500

Skin forming time Visual control of the mixing quality (butterfly test or marble test)

Tack-free time Quantitative check of the mixing ratio by weight

Adhesion test on original materials Pot life(glass, support frame)

Measurement of Shore A hardness Adhesion test on original materials (glass, support frame)

Mechanical properties on H-test specimens Measurement of Shore A hardnessaccording to ISO 8339

Mechanical properties on H test specimens according to ISO 8339

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Triple-tested Quality

Checking Design Drawings

Our FCC check joint design and dimen-sions. This ensures that the anticipatedwind loads and different thermal expan-sions of the substrates are not outside thestressing limits for our silicone adhesives.We subsequently provide technical service in the selection of appropriate siliconesealants for structural glazing,insulatingglazing and weatherseals.

Adhesion and CompatibilityTests

Adhesion tests according to national andinternational guidelines and standards, andour own test methods ensure perfect ad-hesion of our products to the substratesused in any one project. We also test thecompatibility of all materials that come

Project Tests –Safety down to the last Detail

into contact with Sikasil® SG siliconeadhesives. Only compatible materials ensure that there is no negative effect oneither the adhesion behaviour or the mechanical properties of the silicone ad-hesives. The results are provided as a report. We use the results obtained to akerecommendations on surface treatment,e.g. cleaning and priming, of the sub-strates used.

Technical Customer Support

The quality and optical appearance of facades also depend on professional work-manship. We therefore advise our projectpartners to use Sikasil® SG siliconeadhesives and sealants. We will demon-strate how to use them professionally, andhelp with any practical problems.

Duration of Adhesion and Compatibility Tests

Duration of Tests, incl. Report

One-part Adhesive Sealants Sikasil® SG-18, SG-20

Adhesion tests with sealant bead 33 days

UV/water immersion test with H-test specimens 55 days

Compatibility test 33 days

Two-part Adhesive Sealants Sikasil® SG-500


UV/water immersion test with H-test specimens 33 days


All Weather Sealants



Non-staining Sealant Sikasil® WS-355

Non-staining test 45 days

Detailed Project Stages

Individual project testing is carried out ac-cording to a reliable and practicable system,which forms a solid basis for successfulproject execution.

Detailed Project Stages

Note: Detailed information and descriptionsof the practical activities, such as cleaningand priming the surfaces or applying thesealants, can be found in the “structuralglazing application guidelines”. The formsused for the various stages are availablefrom our homepage www.sika.com.

36 | 37

Action Form Performed by

Design Phase

Step 1 Project manager sends all relevant design details (drawings) Project Customerand project details (wind loads, max. temperatures) to Sika for inspection information

Step 2 Sika Design Sikachecks joint details assessmentchecks joint dimensionsassesses the materials usedrecommends the correct sealant for these applications based on all thedetails known

Test Phase

Step 3 Project manager sends all substrates and ancillary materials to Sika for Project tests Customertesting. The number and sizes of the samples are described in the “curtain walls”leaflet “Project Submittal Information”

Step 4 Sika conducts the following tests: Lab report SikaAdhesion tests to all substrates (glass and frame materials)Testing compatibility with all materials that our adhesives and sealants come into contact withBased on the results, Sika makes recommendations for cleaning and, if necessary, priming the surfaces. The results and recommendations are summarized in a laboratory report. Material defects must be eliminated before a warranty is given

Application Phase

Step 5 Sika instructs the applicator on all matters of the applications: SikaCleaning and priming the surfacesAdhesive applicationQuality control during applicationHelp with machine applicationSika also helps with the correct application of its products (e.g. weather-sealing) on site. After successful instruction, the customer receives a training certificate from Sika

Step 6 The customer applies the Sika products as instructed and diligently carries Quality Customerout the recommended quality controls during processing. The quality control controlis documented on the appropriate Sika forms. If desired and agreed, thecustomer sends the test specimens to Sika. Mechanical properties aremeasured in one of the Facade Competence Centres

Warranty Phase

Step 7 Once application of the products is complete, the customer sends all Customerdocuments to Sika for inspection

Step 8 Sika provides a warranty on Sikasil® silicones. SikaFor details please ask the local Sika sales manager.

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... and are also ideally suited for weatherproof joint sealing

Tailored Sealant Systems forall Applications

Sealants are classified according to theircuring mechanism into acidic (which emitacetic acid on curing) and neutral systems(which emit oxime or alcohol on curing).For facades, solvent-free, non-corrosiveneutral technology is used almost exclu-sively. The exceptions are all-glass struc-tures, which can also be sealed withacetic-curing sealants.

Typical Properties of neutralSealants

A wide range of adhesion properties for a variety of applicationsOutstanding adhesion and bonding powerto glass and metal surfacesEarly load-bearing, thanks to high initialelasticityReliable and non-corrosive to sensitivematerials when used in movement joints,expansion, construction and connectionjointsApplication-specific curing time withdifferent vulcanization rates and optimumcuringUniform long-term elasticityGood elastic recoveryDurable and extremely strongOutstanding weathering and ageing resistanceExtremely good UV and oxidation stabilityGood chemical resistance and non-yellowing

Resistant and flexible even with extremetemperature fluctuations from –50 °C to +150 °CLow shrinkage in vulcanizationLong-term resistance to continuous rainfall

Sealant Composition

Sikasil® silicone sealants generally consist of the following components:Silicone polymerSilicone plasticizerSilicone cross-linkerSilicone adhesion promoterReinforcing fillers (e.g. fumed silica)Possibly non-reinforcing fillers, such as silicates, chalks, etc.Optionally, additives such as emulsifiers,pigments and fungicides

Sikasil® Silicone Sealants in Detail –Technical Glossary

Neutral silicones are used for structural glazing ...

Terminology

ElastomerGeneric term for synthetic and natural polymers with rubber-elastic properties

Atmospheric HumidityIn general: the relative humidity (invisible water vapour in the air) that plays an important role in the vulcanization of one-part silicone sealants

PolymerSubstance in which one or more types ofmolecule are linked together

PolymerizationChemical reaction in which small moleculeslink up to form molecular chains (polymers)

Cross-linkingThree-dimensional interlinking of polymerchains to form a polymer network. It is thereason why silicone sealants harden

VulcanizationMethod for converting rubber from a pre-dominantly plastic (pasty) state into an elastic state by cross-linking. The bridges to adjacent molecules are formed by meansof vulcanization agents (cross-linkers)

FungicideChemical compound that inhibits microbialgrowth

Properties and Application Characteristics of one- and two-part Sikasil® Silicone Sealants

One-part Systems Two-part Systems

Ready-to-use grade. Already contains cross-linker and catalyst Basic compound and cross-linker are mixed during application

Supplied in cartridges or foil packs, can be used immediately Supplied in drums and pails, components must be mixed by machine

Easy to use (“field glazing” in two-sided structural glazing, repair Execution under controlled conditions in the factory, resulting inglazing, weatherseals) higher quality of the bond

Require atmospheric moisture for vulcanization at No atmospheric moisture required for vulcanizationroom temperature

Vulcanization starts at the surface and continues inwards Once the components are mixed, curing begins uniformly through-relatively slowly out the joint with a gradual increase in viscosity

Curing rate depends on relative air humidity, temperature and Curing rate depends virtually only on the temperaturejoint depth (see graphics)

Minimum time span between bonding and assembly of the Minimum time span between bonding and assembly of thestructural glazing elements: 2 to 4 weeks, depending on air structural glazing elements: 3 to 5 days, depending on framehumidity and joint dimensions materials

Joint bite limited to maximum 15 mm, otherwise curing Should be used for thicker silicone adhesive sealant layerstakes too long and there is a risk of cracking Greater joint bite than 15 mm possible, since considerably higher

curing rate and lower volume shrinkage on curing

Efficient factory prefabrication of structural glazing elementspossible. Elements are faster to transport and install

Thickness of cured sealant [mm]

Curing rate of one-part silicones such asSikasil® SG-20 or Sikasil® WS-605 S

Shore A hardness in the vulcanization of two-part silicones, such as Sikasil® SG-500 or Sikasil® IG-25,as a function of time

Curing Rate of Sikasil® Silicone Sealants

Curing characteristic of one-part silicones Curing characteristic of two-part silicones-

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Glass Cube; Gehringswalde, Germany

Mechanical Properties

Sealants are classified (e.g. according toISO 11600) by their mechanical properties.

Tensile Stress or ModulusThis is the quotient of the tensile forcemeasured at a particular elongation andthe initial cross-section of the test speci-men. For classification as a low-modulussealant according to ISO 11600 (e.g. ISO11600 25 LM), this must have a modulusof less than 0.45 N/mm2 at 20 °C accord-ing to ISO 8339.

Important: In comparisons of data, theshapes of the test specimens are impor-tant. Measurements with dumbbell specimens according to DIN 53504 and ASTM D 412 give much higher values than those on H-test specimens according

to ISO 8339 or ASTM C1135, which aremore similar to actual joint geometries andare therefore usually used for structuralglazing tests.

Tensile StrengthThis is the quotient of the maximum meas-ured force and the initial cross section ofthe test specimen.

Elongation at BreakThis is the quotient of the change in lengthmeasured at the instant of tearing and theinitial measured length of the test speci-men.

Shore A HardnessThis is the penetration hardness of poly-mers. It depends on the modulus of elastic-ity and the viscoelastic properties of thematerial. Higher Shore A values ensure aharder material. High-modulus structuralglazing silicone sealants usually haveShore A values of over 30. The values forweatherseals are usually between 15 and 25.

Weathering and AgeingResistance

Silicone sealants have better weathering andageing resistance than other joint sealants.Their physical properties do not change,even after years of outdoor weathering.

Compatibility with CoatingMaterials

Silicone sealants are usually compatiblewith coating materials (powder paints, liq-uid paints and varnishes) on the construc-tion materials, but this should always betested. However, standard silicone sealantscannot be painted with liquid coating ma-terial (paints or varnishes). Streaking andrunning usually occurs during application.

Important: Most of the coating materialsused in building construction and in almostall window constructions are less elasticthan sealants. A continuous coating may

therefore tear if the dimensional change ofthe sealant is greater than the elasticity ofthe coating. Elastic sealants in settlementjoints must therefore never be completelycoated. Only sealants subject to low move-ments up to approx. 5% can be coated completely. Sealants coming into contact with coatings must be compatible with them(in conformity with DIN 52452 part 4).

Chemical Resistance

Vulcanized silicone sealants have good resistance to weak acids and alkalis, polarsolvents and salt solutions. Silicone sealantswells to a greater or lesser extent in solvents such as ketones, esters, ethers,aliphatic, aromatic and chlorinated hydro-carbons. It is restored to its original shape after evaporation of the solvents.

IFLEX Park, Bangalore, India

AdhesionTendency of a solid surface to stick to asecond phase, which may be a liquid or a solid film

Adhesion LossUndesirable separation of the adhesionbond, e. g. separation of a joint

Adhesion ValueForce between an adhesive bond, or theforce necessary to separate the bond

CohesionThe integrity of substances as a result ofchemical bonding or physical intermolecu-lar forces

Cohesive FractureUndesirable material fracture, e. g. in thejoint

Some relevant Internet Links:

www.aia.org

www.archinform.de

www.architecture.com

www.architectureweek.com

www.emporis.com

www.eota.be

www.glassfiles.com

www.riba.com

www.uia-architectes.org

Movement Capability

The movement capability is the total elon-gation and compression that a joint sealantundergoes during service. In the case ofsilicone sealants according to ISO 11600,it is between 20 and 25% of the initialwidth. According to ISO 9047, classification25 is based on elongation and compres-sion cycles with an amplitude of ±25%.

Adhesion

Silicone sealants adhere very well to manysubstrates. The adhesion depends on thetype of material to be bonded, the stresses,the type of adhesive bond and surfacetreatment. The surfaces must be absolutelyclean and grease-free. Before the start ofsealant application on any constructionprojection, always carry out adhesion testson the surfaces in question.

Terminology

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High and low TemperatureBehaviour

The stress/strain value (modulus) of sili-cone sealants – unlike organic sealants –remains practically constant over a widetemperature range from –30 to +80 °C.The tensile strength increases at low tem-peratures. Silicone sealants are thus idealfor compensating for joint expansionsoccurring as construction elements cool to low temperatures. The tensile stressesin the joint flanks are not increased, andthere is reduced risk of loss of adhesionand consequent adhesive fracture. Below–50 °C, there is partial crystallization ofthe silicone elastomers and the sealanthardens. At –123 °C (the glass transitiontemperature) embrittlement occurs.

Silicone sealants are extremely heat resist-ant. In dry air up to +150 °C, all grades retain virtually their full elasticity. Specialsilicone sealant grades are even heat re-sistant up to +250 °C. It is important that silicone elastomer should be fully vulcanizedbefore it is subjected to high temperatures,and that the curing by-product has evapo-rated completely. Heat resistance can be further enhanced by subsequent annealing at slowly increasing temperature and withgood ventilation.

Shelf Life

If stored in the original sealed containers attemperatures below 25°C, silicone sealantshave a shelf life of at least 12 months, andsome grades at least 18 months.

Gas and Water VapourPermeability

At room temperature, the gas permeabilityof silicone sealants is about ten timeshigher than that of natural rubber. At 100°C to 150 °C, the permeability valuesare approximately the same. The watervapour permeability according to DIN53122, climate D, film thickness 2 mm,is approx. 20 gm-2d-1.

Coefficient of Expansion

The coefficient of cubic expansion of silicone sealants depends on the natureand the amount of fillers used. It is in therange 4 �10-4 K-1 and 8 �10-4 K-1.The coefficient of linear expansion is ap-proximately a third of the cubic expansion,i. e. from 1 � 10-4 K-1 to 3 � 10-4 K-1.

Basic Rules

Low-modulus silicone sealants must not beused for structural glazing bonding

Acetoxy-curing silicone sealants are incom-patible with alkaline substrates such asmortar and concrete, and with corrosion-sensitive metals such as lead, zinc, copper,brass and ferrous metals

Fungicide-containing sealants must not beused for the production of aquaria

Standard silicone sealants must not be usedfor sealing settlement joints and expansionjoints between porous natural stone (e.g.granite, marble, sandstone, etc.). There is a risk of staining.

Standard silicone sealants can cause envi-ronmental stress cracking in contact withpre-stressed acrylic and polycarbonate construction elements

Silicone sealants do not adhere to poly-ethylene and polytetrafluoroethylene

Contact with organic elastomers (such as EPDM and Neoprene) can not only causediscoloration of the sealant but can also reduce its mechanical strength and causeadhesive failure

Special Solutions –Restrictions on Use

Please note the incompatibilities mentionedhere. Sika has developed special products to cover most problems. Further informationis provided in the data sheets. We will bepleased to advise you on any type of applica-tion problem and find a solution.

Thermal Conductivity

The thermal conductivity of siliconesealants depends on the nature and theamount of fillers used. It is in the rangefrom 0.15 to 0.25 W K-1m-1 at room temperature (DIN 52612).

Physiological Characteristics

All silicone sealants emit by-products oncuring. They may be acetic acid, alcoholsor oximes, depending on the sealantgrade. We therefore advise users to readthe data sheet and safety data sheet inadvance. In general, they should be ap-plied in a well-ventilated room. Vulcanizedsilicone sealants are non-toxic. Specialgrades are available for contact with foodsand drinking water.

Microbial Resistance

Unlike organic sealants, silicone sealantsare not attacked or degraded by microbes(bacteria or fungi). However, microbes canaccumulate on the surface of dirty siliconesealants, particularly in warm and moistconditions occurring in bathrooms andkitchens. This causes discoloured patcheson the sealant surface without its mechan-ical properties changing. For warm andmoist applications, therefore, a fungicide-containing sealant should be used.

Extension of State Department, Berlin, Germany; design of glass facade: James Carpenter Design Associates

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Sealing and Bonding in Facades –A Specification Guide

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Customer ServiceSika Engineering Silicones Srl.Via L. Einaudi, 6I-20068 Peschiera Borromeo (MI)Phone +39 02 516591 205Fax +39 02 516591 [email protected]

www.sika.com

Our most current General Sales Conditions shall apply. Pleaseconsult the Product Data Sheet prior to any use and processing.

Sika® Facade Systems

Sealing and Bonding in Facades – A Specification Guide

Technical ServiceSika Services AG Facade Competence CentreTüffenwies 16CH-8048 ZürichPhone +41 56 648 5287Fax +41 56 648 [email protected]

Sika is a globally active company in the speciality and construction chemicals business. It has subsidiary manufacturing,sales and technical support facilities in over 70 countries around the world.

Sika is THE global market and technologyleader in waterproofing, sealing, bonding,dampening, strengthening and protection of buildings and civil engineering structures.

Sika has more than 11’000 employeesworldwide and is therefore ideally positionedto support the success of its customers.

Sika – Your Local Partner with a Global Presence

Facades by (Project No): Josef Gartner GmbH (3, 5, 13, 14, 18, 21, 27); Schmidlin AG (1, 2, 17, 22, 23); Yuanda (6, 8, 19); Cuhadaroglu (11, 20, 26); Mero (4, 25); Alico (7); Compact Metal (9); Inasus (12); Vitro Cristalglass (16); Photos by: Gardin & Mazzoli (14, 18); Daniele Domenicali (Front, 3); Guy Nowell (13); Beyond Architecture Cultural Development Co Ltd, Mr. Zhou Li (21); Schmidlin AG (1, 2, 17, 22, 23);

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