Construction site weather shielding and condition control

The sole responsibility for the content of this publication lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EASME nor the European Commission are responsible for any use that may be made of the information contained therein.

The control of conditions on building site

• The control of conditions on site means the practises which will ensure• Conditions of material installation • Hardening of concrete • Drying of structures• Producing healthy buildings

• Actions• Schedule control• Decent weather guard, heating and air ventilation• Checking and regulating conditions, when needed

§ Gleaned from building regulations:

• A building needs to be designed and constructed to ensure it won’t cause hygiene or health risk to the users or the neighbours when moisture condensates to the parts of the building or inner surfaces of the building. (Building regulations C2, 1.2 Essential requirement)

• Those properties of a building must remain, with typical maintenance, the whole economically reasonable lifespan.

Exercise: Give examples of what the text means in practise on site?

3

Correct site conditions are important because:

•floors.

• in autumn the concrete won’t dry off.• in winter cold air trickles onto floor hence the concrete honing is delayed.• in spring dry air causes concrete cracking.• in summer wind and heat may cause concrete cracking.

Also too cold or too dry base may cause quality issues in concrete

Tampere estmated

The number of rainy days and the amount of rainwater

On average, it rains or snows every third day.

Month Helsinki Tampere Jyväskylä Oulu

I 10 10.5 11 8

II 8 7.5 7 7

III 8 8.5 9 7

IV 7 7.5 8 6

V 6 6.5 7 7

VI 8 8.5 9 8

VII 8 9.5 11 9

VIII 11 11 11 10

IX 10 10 10 9

X 10 11 12 9

XI 12 12 12 10

XII 11 11 11 9

I-XII 109 118 99

The number of rainy days (rainwater = 1.0 mm)

Month Helsinki Tampere Jyväskylä Oulu

I 47 45 43 30

II 36 33.5 31 23

III 38 37.5 37 24

IV 36 36.5 37 20

V 32 35 38 30

VI 49 54 59 45

VII 62 70.5 79 60

VIII 78 83 88 66

IX 66 64.5 63 42

X 73 66.5 60 41

XI 68 62.5 57 36

XII 58 52.5 47 30

I-XII 643 639 447

The amount of rain (mm)

Source: Finnish meteorological institute. Estimates counted during the years1971-2000.

Rain 1 mm = 1 l/m2

Snow 1 cm = 1 l/m2

Conditions

Sources of structural moisture

E.g. in Helsinki the amount of rainfall in September onto 500 sqm concrete floor is 500 m2 x 73 l/m2 = 36 500 l

Exercise: How much, in a typical rainy day in autumn, rains water falls on one section of the apartment block? The section contains the apartments of a stairwell (about 400m2). The amount of rainwater in a one day is 20 mm.

Answer: 400 m2 x 20 l/m2 = 8000 litres.

Concrete 8-9

Smoothing compound 1-1.5

Interior plaster 0.5

Rainwater 1-5

Total 10-16

Masonry walls 5-7

Moisture sources, fully prefabricated building

l/Rm3

l/Rm3

l/Rm3

l/Rm3

l/Rm3

l/wall-m2

Excessive water tightness of base floor

Connection of vertical joints

Lifting lugs, fixing points,balcony brackets

Pain points of moisture management

Bendy slab brings water to load bearing walls

Difficult to weather protect

the heat insulations

Suspension rods complicate

the use of tarpaulin

• Usually lots of rainwater runs off from concrete floor to heat insulate.

• While installing, one must consider that the water can release in a controlled way from structures.

• Also when using the building, the moisture can condense on the inner surface of cladding. Ventilation routes must always be in accordance with plans.

The water drainage holes of the base wall should not covered!

Drying solutions

Concrete construction work

• Concrete structures tolerate moisture well but they should dry completely before coating works.

• The humidity of concrete structures must be measured before the coating works.

• Timber and precast concrete units at same site require special planning because the evaporated water easily condenses on the surface of timber units.

Energy-efficient and moisture-safe installations

The insulation and ventilation solutions must be suitable for manufacturing, installing and occupatian.

Details can be difficult to make, but they need to be made carefully so they will last decades.

Co-operation on site

• Co-operation with supervisor, subcontractors and workers helps create good construction conditions.

• Must arrange and remember• Protection methods

• Working order

• Scopes of contract

Supplier’s liabilities

Products must be delivered

• On site, dry and water sealed

• To intermediate depots and properly stored.

Supervision of crucial structures

• In advance, it must be agreed with supervisors how energy efficient and healthy structures will be built, controlled and confirmed on the construction site.

• It must be taken into account that the work methods are chosen according to design concept.

Construction site weather shielding

The sole responsibility for the content of this publication lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EASME nor the European Commission are responsible for any use that may be made of the information contained therein.

Construction site weather shielding

• Weather shields maintain a dry site. The costs of shielding can be high, but better productivity, occupational safety and quality means significant economical savings.

Exercise: Give examples of how weather guards can help decrease the costs.

• When tented the work continues despite of raining.

Construction site weather shielding

• Air humidity must be monitored when working in weather shield. • If RH rises constantly over 60%, must ventilation must be

increased.

A yearly tradition?

8.3.2011 Oulu(YLE.FI)

25.3.2013 Vantaa(YLE.FI)

15.05.2010 Helsinki(Eteläsuomen sanomat)

28.12.2014 Helsinki (MTV3.fi)

Water tight floor, ”finished first time”

Water tight floors and sandwich panels create dry working conditions on floors below.

More about method: www.tut.fi/site

Facade could be closed– already at factory

Notice when installing :

• The position of elements can’t be checked from windows → Installation line marks inside the element

• Windows protection in the factory

• It takes more time to create supply contracts

• The windows can be installed in the elements already at the factory Less heating and covering on site.

Roofs

• A roof can be ready built on the ground and hoisted into place. • This saves both labour cost

and indirect cost.

• No need for scaffolding nor safety railings…

• Roof insulation can be installed immediately after frame work and drying can start quickly.

Principal of dry construction

Dry construction

1. The roof and the envelope the building are waterproof or built inside the weather guard.

2. Relative humidity is less than 70%.3. (Temperature over 10 °C, heating on.)

Exercise: List construction works that need to be made by following the rules of dry construction.

Working plan of dry construction

• The weather guard planning is a major part of the working plan.

• Construction plans, materials, scaffolding, weather guard and equipment for critical works are good to get when the weather is good.

• Always be prepared for rain. On average, it rains or snows every third day.

• Also construction sequence can help or ruin the success of dry construction

Exercise: List examples of mistakes in construction sequence.

• Different moisture resistance of different materials• Targets of site condition and the methods of control• Protection of site, structures and materials• Other requirements for site (previous work,…)• Heating and drying methods• Any special characteristic of the construction site

Considerations for dry construction:

Building in winter

• Cover all structures from rain and snow.

• Close the envelope carefully – especially large openings.

• Install temporary front doors in balcony-access blocks.

• In tower blocks temporary doors or tarpaulins may be used.

• Mechanically remove snow, do not melt it.

The sooner you close the envelope the more you benefit!

Good conditions promote productivity, increase performance, reduce interruptions, increase work motivation, create positive image.

Protecting material

Shielding• Rising damp• Rain

Take care of• Ventilation• Leachate

Remember• Transportation cover does not protect from rain sufficiently• Avoid extended storage periods

Short-term storing outdoors

• Factory installed protection of these windows is not sufficient.

• Notice water flow. Water must not stay under or on top of material.

• Windows remain outside for a short while, waiting to be transported indoors. Always prevent ground contact.

The good practices and principles required for the energy efficient building have been included in the teaching material. The writers are not responsible for their suitability to individual building projects as such. The individual building projects have to be made according to the building design of the targets in question.

Thank you