INSIDEthis issue

INTRODUCTION

The historic Lancaster Houston Hotel, located in Houston,TX, is a twelve-story structure built in 1926 (Fig.1). Originallyknown as “The Auditorium Hotel,” the Lancaster was desig-nated a Recorded Texas Historic Landmark by the TexasHistorical Commission (THC) in 1984.

GUESTS COLUMN:

FAll 2016 newSleTTeR

(Continued pg. 2...see RE-ROOF OR RE-COVER?)

(Continued pg. 2...see PHOTOGRAMMETRY)

Frost Bank Raises The Bar......2 -3

Photogrammetry....2 - 4

Chamberlin Receives Awards....................5

Projects in Progress...6

www.ChAmBeRlinlTD.COm

By Diego Romero and Al Bustamante,Walker Restoration Consultants

Diego F. Romero, Ph.D., P.E.Restoration Consultant

Al Bustamante,Director of Restoration

Re-roof or Re-cover?

Facade Restoration Using Photogrammetry

The completed torch-applied roofing system for an leading environmental agency’s headquarters in Austin, TX.

A lead environmental agency for the state of Texas recently faced roofing issues at their headquartersin Austin, TX. The facility was built in 1992 and iscomprised of seven buildings. The existing standingseam roof on one of the buildings was starting to fail.The metal panels were coming apart, rust spotswere emerging and the HVAC units needed to beupgraded. With a long history of remedial roofingprojects, as well as substantial metal roofingexperience, Chamberlin Roofing & Waterproofingwas selected by General Contractor Kiewit BuildingGroup to complete the roofing scope for this project.

Weighing The Pros and ConsDeciding between a new roof or to re-cover theexisting roof is the first decision a building owner must

consider. A re-cover is the installation of a new roofingsystem over an existing roof. It is the quickest andleast expensive option. There is a reduction in debristo manage, minimal noise and less of a risk for theowner because you are not tearing off the roof andexposing it to water damage. When you demo a roof,there are safety and health factors to consider- willthe debris become a safety nuisance? Will there beasbestos in the roof? However, working on an existingroof comes with its own challenges. As with mostroofs, a variety of roof equipment is already installed,therefore you are not working with a clean slate.

A re-roof is the complete removal and replacementof an existing roofing system. With a re-roof, your roof

CONDITION ASSESSMENT

Exterior wall evaluations were performed inphases for several years and different types ofdistress conditions were identified. The mostsignificant deterioration occurred on the toplevel of the structure on the south and westelevations. Typical observations included cracksat the spiral columns and mortar joints, localizedsurface spalling of cast stone trim and spandrelpanels (Fig. 2) and missing ornamental caststone spiral columns and brackets.

Based on our conclusions, we recommendedsealing facade cracks greater than 0.012 inches(0.3 mm) in width, repairing localized cast stoneand masonry spalls in the facade and removingdeteriorated cast stone units to replace them inkind. The cast stone replacement encompasseda total of 28 column and bracket units and 14spandrel panels. The focus of this article is onthe spandrel panel cast stone replacement.

RESTORATION PLAN

Original construction documents were notavailable for this building and made the caststone replacement even more difficult. Withoutany details, our only option was to make a moldout of the physical cast stone ornaments. Weproposed two methods to the contractor tocreate the molds. First, the conventionalapproach which required vertical access to thefacade, removal of a spandrel panel, columnand bracket in good condition and, finally,manufacturing the molds. This method, althoughtried and true, is costly and comes with theinherent risk of damaging the delicate cast stonefeatures. The second method proposed was touse 3D scanning and modeling technology tocreate a three-dimensional model of thearchitectural features and use the model tocreate a negative mold or a master copy. Thismethod removes the risk of damaging a caststone piece in good condition.

deck can be thoroughly inspected forany underlying issues and correctedprior to new roof installation. However,it is more expensive because morelabor is involved with tearing off theexisting roof. The construction can alsopotentially disrupt day-to-day businessdue to the demo process

Wiss, Janey Elstner Associates (WJE)was hired to conduct a roof survey toweigh the options, and determine if thestructure would be capable to supportthe extra weight of another roof. Withconfirmation that it would, a re-coverwas decided on, as it was the mostcost-effective choice and also tomitigate business disruption.

The design for the roof re-cover wasnot your ordinary design. Because ofthe existing roof equipment – 52 HVACunits, four satellite dishes and 15plume exhaust fans – the roofing crewneeded to work meticulously to detailin the curbs. The roof insulation alsohad to be chamfered to fit inside theexisting metal panel profile.

The ScopeChamberlin installed 25,000 squarefeet of torch-applied modified roofingsystem and flashed the new HVACroof top units. To ensure the HVACcurb units were watertight, Chamberlin

installed a self-adhered vapor barrierflashing to the existing standingseam roof.

First, chamfered insulation wasmechanically attached through a metalpanel to steel purlins. Once attached,another layer of ISO was installedwith a urethane adhesive. Then, agypsum-fiber roof board was installedwith a urethane adhesive to act as acover board and thermal barrier. TheSBS base sheet was applied directly tothe cover board, then the cap sheetwas torched to the base sheet. On thevertical walls, Chamberlin torched thebase and cap flashing to the plywoodand installed a termination bar at thetop of flashing. The cap sheet wasembedded with ceramic granules togive the roof the required SRI value.The crew then fabricated andinstalled stainless steel sheet metalcounter-flashings and copings.Stainless steel was the best choice forthis project because it is very durable,never corrodes and holds up wellagainst weather.

Safety is #1The importance of safety is critical foreach project Chamberlin undertakes.To begin, parapet clamps were installed on the low parapet walls on

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(RE-ROOF OR RE-COVER? Continued from pg. 1)

(PHOTOGRAMMETRY Continued from pg. 1)

ACTIVE MEMBER OF:

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Chamberlin had to work around the extensive existing rooftop equipment.

Figure 1: Overall view of the Lancaster Hotel in foreground

Parapet clamps were used as one fall protection method while the basesheet and cap sheet were being inst

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(RE-ROOF OR RE-COVER? Continued from pg. 2)

(Continued pg. 4...see PHOTOGRAMMETRY)

Given that the contractor had already mobilized onsite, a combination of both methods was selected tomanage risk and costs. This involved manufacturingtraditional molds out of physical spiral column andbracket samples (due to their small size) and creatingnon-traditional molds from 3D models for the delicate60 x 22 inch (1524 x 559 mm) spandrel panels. Weevaluated different methods to create the 3D modeland determined that photogrammetry was the mostcost-effective and practical method.

Photogrammetry is the science of makingmeasurements from photographs. In short, computeralgorithms attempt to identify points in commonbetween a set of photographs and plot them in athree-dimensional space (i.e. a point cloud). Once thepoint cloud is created, a mesh which connects all theindividual points with flat planes can be generatedusing traditional modeling software. A 3D mesh allowsan engineer to manipulate its dimensions and shapes,analyze the object for stresses and strains, 3D printthe model or use a computer numerically controlled

the East, West and South sides of the roofto extend the height above 39 inches for fallprotection on those elevations. The Northwall on the gutter side had no parapet wall.In lieu of a warning flag line, which is com-prised of a rope and flags hanging 34” tall,Chamberlin went a step further and createda safety guard rail system built of 2X4sstanding over 39” tall and installed it ten feetfrom the leading edge. This acted as a safeguard for not only Chamberlin employees,but also other trades and authorizedindividuals accessing the area.

Since the roof did not have existing tiebacks,butterfly anchorage points were installed onthe North side for the crewmembers to tie offto while working outside the guardrail. Theseare hinged, temporary anchor points that aremechanically fastened to the roof and arecapable of withstanding 5000 pounds.

The roofing crew utilized yo-yos and full bodyharnesses for Personal Fall Arrest Systems.The yo-yo is a self-retracting lifeline thatallows for increased mobility and unrestrictedmovement compared to a traditional lanyard.These allowed the crewmembers to installalong the entire north side of the roof withouthaving to move their butterfly anchors alongwith them. Doing so would have been laborintensive since each anchor is bolted to theroof with 16 screws. Also, another methodof fall protection would have had to been

employed while the butterfly anchor wasunhooked from the roof. Additionally, if afall were to occur, a yo-yo limits the fallingdistance, catching immediately with itsquick-activating brake system.

Once the gutter and edge of roof work wasfinished, the guardrail was removed in orderto complete the installation of the roofingsystem, and replaced with safety flagginginstalled six feet from the leading edge. Theproject was completed safely and efficientlywith no incidents.

Rain, Rain Go AwayWith record breaking rain fall in May andthe wettest August since 2001 constructionwas periodically on hold. There was anaggressive schedule from the beginning,by the owner’s request so working overtimeand on Saturdays became the routine tostay on schedule because of the rain days.Keeping the lines of communication openand coordinating with the owner, consultant,manufacturer and general contractor werecrucial to staying on schedule. Chamberlinfinished their scope of work on time and withzero incidents, remedying the roof issuesand leaving the building watertight.

(PHOTOGRAMMETRY Continued from pg. 2)

The HVAC units were flashed to keep the building watertight.

Chamberlin installed 25,000 square feet of torch-applied roofing system.

Figure 2 Cracked and spalled cast stone at facade spandrel pa

A guardrail system was built on the North side of theroof where there was no parapet wall..

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(CNC) mill to create our shape. The mainadvantages of photogrammetry include thismethod being extremely portable and onlyrequiring a camera, a trained photographerand a computer modeler.

DEVELOPING THE 3D MODELS

The general procedure was as follows:While on the suspended scaffold, hundredsof photographs were taken of the spandrelpanels, columns and brackets usingindicator targets in the objects so thephotogrammetry software is able torecognize similarities between photographs.The photographs were then manually sortedto delete photographs that were either blurryor not part of the data set needed. Oncesorted, the photographs were uploaded to acommercially available photogrammetrysoftware package to process the pointcloud. Once processed, the point cloud wasimported to a free and open-source 3Dmodeling software in order to create a solidsurface mesh that connects all of the pointsin the point cloud (Fig. 3). The time it takesto process a mesh is highly dependent onthe complexity of the geometry and thedensity of the point cloud. For reference,the decorative spandrel took approximatelythree hours to generate the point cloud, onehour to mesh and three hours to edit themodel and complete the final touches.

As a trial, we used 3D printing to determineif the models were detailed enough for fullscale production. A partial model of thespiral column and capital was generated,edited and printed using a MakerBot 3Dprinter and biodegradable thermoplasticaliphatic polyester filament, commonlyknown as PLA. The result was a miniatureversion of the column with all its surfacedefects and details (Fig. 4). Pleased withthe results, it was time to move forward withthe full scale replica of the spandrel panel.

DESIGN OF CAST STONESPANDREL PANELS

Matching the existing features of the existingspandrel panels required using cast stoneas our final product. Cast stone, as definedby the Cast Stone Institute, is a refinedarchitectural concrete building unitmanufactured to simulate natural cut stone.The materials and processes used in themanufacturing of the stone depend onthe required appearance and physicalproperties. Our specifications requiredproducing cast stone with a minimum28-day compressive strength of 6500 psi(44.8 MPa), a 28-day absorption rate

ranging between 6% to 8% and shrinkagenot to exceed 0.065%. Additionally, the caststone was to be reinforced using eithernon-corrosive reinforcement or weldedwire fabric with a minimum reinforcement of0.25% of cross sectional area.

The existing cast stone spandrel panels aresupported by a steel shelf angle connectedto the building frame with post-installedanchors and are laterally supported bycorrugated metal ties. For the replacementpanels, we utilized the same steel shelfangle to support the gravity loads andsecured each panel with four new stainlesssteel post-installed chemical anchors toresist lateral wind loads. The chemicalanchors were detailed to be installed at anangle of 15 degrees from the horizontal

plane to provide a mechanical interlockbetween the anchor and the caststone spandrel.

FABRICATING THE SPANDREL PANELS

The method used to create the molds wasCNC low-density foam to form the shape,create a rubber mold and then use caststone to create the spandrel. This methodoffers relatively low costs, ability for thecontractor to cast their own units and theimproved durability provided by cast stoneover polyurethane-coated high density foam.

A StereoLithography (STL) file wasexported and sent to the manufacturer.This file format is widely used for rapidprototyping, 3D printing and computer-aidedmanufacturing. Using a three axis CNCmachine, a foam master copy of thespandrel panel was milled and sanded. Thefinal master copy coated with polyurethanewas delivered to the project site ready forthe mold-making process.

Molds made of liquid urethane werefabricated from the master copy. The caststone panels were fabricated at a plantusing the master copy, delivered to thesite and installed (Fig.5).

CONCLUSION

The distressed spandrel panels weresuccessfully replaced with new cast stonepanels that closely match the shape, size,texture and color of the original cast stonepanels maintaining the historic significanceof the building. Based on this projectexperience, we are confident thatphotogrammetry can be implemented in anyproject requiring replacement of ornate orhistorical building features without the riskof damaging the existing conditions of thefacade and at the same time reducingdesign and construction costs.

(PHOTOGRAMMETRY Continued from pg. 3)

Figure 3: 3D model of spandrel panel developed withphotogrammetry

Figure 4: Left - Existing decorative column, Middle - 3Dmodel of column, Right - 3D print of model

Figure 5: New cast stone spandrel panel installeDiego Romero, Ph.D., P.E. is a Restoration Consultant for WalkerRestoration Consultants in Chicago, IL. He earned a doctoral degreein civil engineering from the University of Miami. He is a memberof the American Concrete Institute (ACI) and the InternationalConcrete Repair Institute (ICRI) and has experience in analyzingand restoring structures ranging from 19th century churches tomodern day power plant cooling towers. 312.633.4260Diego.Romero@walkterrestoration.com

Al Bustamante is the Director of Restoration for Walker RestorationConsultants in Houston, TX, and a licensed Professional Engineer.He earned his master’s degree in civil engineering from the Universityof Illinois. He has over 15 years of experience as a restorationconsultant in a variety of structural, architectural and materialdistress related projects. He is a past president of the Houstonchapter of the Structural Engineers Association of Texas (SEAoT),American Concrete Institute (ACI) and the American Instituteof Steel Construction (AISC).

Chamberlin has recently been honoredwith several awards for outstandingworkmanship and safety on the job. Weare proud of our team and recognize thattraining, hard work and a dedication todelivering more to our clients makes forsuccessful projects.

Chamberlin received an Associated GeneralContractors (AGC) Texas Building BranchOutstanding Construction Award for fourdifferent projects:

• Parkland Hospital Sky-Bridges – Dallas, TX

• Austin Bergstrom International Airport Consolidated Rental Car Facility – Austin, TX

• Clinical Services Wing – Galveston, TX

• Love Field Modernization Program – Dallas, TX

This awards program recognizes outstandingconstruction projects built by AGC members.Projects are evaluated on difficulty in con-struction, unusual construction techniques,final appearance and quality of the finishedproduct timeliness of completion and safety.

Associated Builders and Contractors, Inc.(ABC) believes world-class safety programshave three main components: a commitmentfrom company leadership to embrace safetyas the core value upon which decisions aremade, a top-to-bottom safety culture thatempowers all employees to create the safest

work environment possible and systems andprocesses that focus on how to prevent ahazard or incident from occurring. Their Safety Training Evaluation Process(STEP) helps companies assess andimprove their safety programs. ChamberlinRoofing & Waterproofing achieved STEPDiamond status, the highest STEP level, in2016 for the second consecutive year.Chamberlin will continue to keep safety as atop priority on every job they undertake to gettheir workforce home safely each night.

Chamberlin Roofing & Waterproofing wonfirst place in TEXO’s 2016 DistinguishedBuilding Awards competition in the OtherSpecialty Contractor category for their roofinginstallation on the Love Field ModernizationProgram in Dallas, TX. Chamberlin installed450,000 square feet of torch-applied, two-plymodified bitumen roofing for the airport’s

renovation and expansion. The DistinguishedBuilding Awards embody the skill,commitment and passion that TEXO

members have for construction.The projects are judged based ondifficulty in construction, innovativeconstruction techniques, finalappearance and timelinessof completion.

The Associated GeneralContractors of America (AGC)Houston chapter’s Awards forProject Excellence (APEX) programhonors firms for their excellencein construction, their valuablecontributions to the community andtheir demonstrated commitment toskill, integrity and responsibility.Chamberlin is the proud recipient ofan APEX award for their roofing andwaterproofing work on the KirbyTowers Renovation in Houston’sGreenway Plaza district. Their scopeincluded a unique roofing system onan amenity deck boasting a puttinggreen for the tenants.

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Chamberlin Honored with Numerous Awards for Excellence & Safety

Cutline

Kirby Towers in Houston, TX

Cutline

Love Field in Dallas, TX

PROjeCTS in PROGReSS

lOCATiOnS:

Call the nearest local office or 1-800-749-1432

hOUSTOn

DAllAS/FT. wORTh

OklAhOmA CiTY

SAn AnTOniO

AUSTin

7510 LangtryHouston, Texas 77040Ph. (713) 880-1432Fax (713) 880-8255

2170 Diplomat DriveFarmers Branch, TX 75234Ph. (214) 273-9110 Fax (214) 273-9120

1515 Dungan Lane, Ste. 210Austin, TX 78754Ph. (512) 275-1600Fax (512) 275-1603

912 Messenger LaneMoore, OK 73160Ph. (405) 680-0506Fax (405) 680-0508

TUlSA10828 E. Newton Street, Ste. 117Tulsa, OK 74116Ph. (918) 439-0055Fax (918) 439-0067

9035-E Aero StreetSan Antonio, TX 78217 Ph. (210) 822-6536Fax (210) 822-8211

ST. MARTHA CATHOLIC CHURCH – HOUSTON, TXRemedial waterproofing   Contract Amount: $165,000 (approx.)Owner: Archdiocese of GalvestonConsultant: French EngineeringScope of Work: Cleaning and power washing limestone, brick and precast surfacesProject Description: Church

CARROLLTON POLICE HEADQUARTERS – CARROLLTON, TX

new Construction waterproofingContract Amount: $600,000 (approx.)Owner: City of CarrolltonArchitect: Perkins+WillGeneral Contractor: Turner Construction CompanyScope of Work: Formed metal fabrications, wood blocking, cap wall and curb flashing, thermoplastic membrane roofing, sheet metal coping, gravel guard, counter flashing, sheet waterproofing, air barrier, cavity insulation, joint sealants, flashing and site sealantsProject Description: New addition to Carrollton Police Headquarters

1600 WEST LOOP SOUTH – HOUSTON, TXnew Construction waterproofing Contract Amount: $3,025,000 (approx.)Owner: Tilman FertittaArchitect: GenslerGeneral Contractor: TellespenScope of Work: Below-grade waterproofing, traffic coating, weather barrier, joint sealants, site sealants, water repellents, fluid-applied waterproofingand expansion jointsProject Description: A 10-acre site with 240 room luxury hotel, boutique office space, parking garage and convention center

THE DRISKILL – AUSTIN, TXRemedial waterproofingContract Amount: $875,000 (approx.)Owner: Hyatt Hotels CorporationConsultant: Building Consultants, Ltd.Scope of Work: Concrete demolition, concrete installation, framing, sheet metal flashing and trim, balcony waterproofing and plasteringProject Description: Balcony repairs on historic hotel

SPEC’SWINE, SPIRITS & FINER FOODS – DALLAS, TXRemedial Roofing Contract Amount: $200,000 (approx.)Owner: Spec LiquorGeneral Contractor: Embarcadero AdvisorsScope of Work: TPO roofing system and sheet metalProject Description: Liquor store with New York-style deliAlso licensed in

Arkansas, Louisiana andNew Mexico.

ROOFinG/SheeT meTAl wATeRPROOFinG/CAUlkinG ROOF mAinTenAnCe/leAk RePAiR• Roofing & waterproofing expertise• Leak repair specialists• Preventative roof maintenance plans• Roof & building envelope surveys• Proactive Roof Asset Management • On-call service 24 hours/365 days a year• Free estimates

• Modified Bitumen/BUR• Single ply • Reflective coatings• Vegetative roofing• Metal standing seam• Roof related sheet metal• Tile

• Joint sealants• Membrane waterproofing• Elastomeric wall coatings• Traffic coatings• Expansion joints• Dampproofing/flashing• Water repellents/metal flashing

BUilDinG/GARAGeReSTORATiOn• Concrete/Masonry restoration• Exterior cleaning & coating• Epoxy & grout injection• Bearing pad replacement• Structural repair• Paver repair & replacement

For a complete list of specialty contracting services, visit www.chamberlinltd.com.

OKLAHOMA UNIVERSITY RESIDENTIAL COLLEGE – NORMAN, OK

new Construction waterproofingContract Amount: $185,000 (approx.)Owner: The University of OklahomaArchitect: ADG, Inc.General Contractor: JE Dunn ConstructionScope of Work: Bentonite waterproofing, site and paving sealants, spray-applied air barrier, joint sealants and water repellentsProject Description: Student housing expansion on residential college

SHOPS AT CLEAR FORK – FORTWORTH, TXnew Construction waterproofing Contract Amount: $1,100,000 (approx.)Owner: Simon Property GroupArchitect: Nelson PartnersGeneral Contractor: The Beck GroupScope of Work: Hot fluid rubberized asphalt waterproofing, sheet waterproofing, traffic coating, thermal insulation, spray-applied air barrier, sheet metal flashing and trim, flexible flashing, firestopping, joint sealants, site and paving sealantsProject Description: Upscale mixed-use development

SAIA CONRAC – SAN ANTONIO, TXnew Construction Roofing & waterproofingContract Amount: $2,635,000 (approx.)Owner: San Antonio International AirportArchitect: TranSystems Corporation Inc.General Contractor: Turner Construction CompanyScope of Work: Exterior metal soffit panels and escalator soffit panels, insulation, cold fluid-applied waterproofing, water repellent, traffic coating, expansion joints, joint sealants and air barrierProject Description: Rental car and public parking facility at the San Antonio International Airport

MENIL DRAWING INSTITUTE – HOUSTON, TX new Construction Roofing & waterproofing   Contract Amount: $1,415,000 (approx.)Owner: Menil FoundationArchitect: Johnston MarkleeGeneral Contractor: Gilbane Building CompanyScope of Work: Self-adhered waterproofing, HDPE waterproofing, air barrier, metal flashing, membrane flashing, dampproofing, joint sealants, single-ply roofing, sheet metal and water repellents Project Description: New addition to the Menil Drawing Institute dedicated to the exhibition, study, conservation and storage of modern and contemporary drawing

3M INNOVATIVE CENTER– – AUSTIN, TXRemedial waterproofingContract Amount: $170,000 (approx.)Owner: 3MGeneral Contractor: Craft CorpScope of Work: Window washing, water repellent and joint sealants Project Description: Waterproofing repair on 3M visitor building