INSIDEthis issue

Mid-century through 1980s buildings with lock-strip or“zipper-gasket” glazing systems are an ever present part of theurban landscape in many cities across North America. Althoughthese systems are considered outdated by many and seldomused in new construction, the systems have performanceattributes that should merit respect.

CONSULTANT’S CORNER:

wInTeR 2018 newSLeTTeR

(Continued pg. 2...see THE BUCKINGHAM)

(Continued pg. 2...see LOCK-STRIP GASKET REPLACEMENT)

Restoring The Buckingham Balconies .............................2 -3

Lock-Strip GasketReplacement &Remediation Strategies ............................2 - 5

Industry Honors........5

Projects in Progress....6

www.CHamBeRLInLTD.COm

Restoring The Buckingham Balconies

Lock-Strip Gasket Replacement & Remediation Strategies

One hundred and forty-four balconies were restored at The Buckingham senior living community in Houston, Texas, to remedy water infiltration.

The Buckingham is a four-story senior livingcommunity located in the center of Houston, Texas.This establishment encompasses over 200 residences,with a balcony attached to each exterior unit. Due tounknown issues during original construction, thewaterproofing and flashing details installed on thebalconies failed, allowing water infiltration that caused extensive damage over the years. The framing members were deteriorated, and the plywood decks rotted, with many requiring completedemolition and rebuild. A nearly two-year-long project kicked off to fully restore and waterproof144 balconies at The Buckingham.

THE PROCESS

Chamberlin was conscious of the residents’ schedulesand strived to keep interruptions to a minimum. Workonly commenced from 8:00 a.m. to 4:30 p.m. daily.Crews began their work by sealing the windows onthe exterior side with window film to help mitigate dustpenetrating the tenant’s living space. When needed,insulation was added to muffle noise as well.

Chamberlin used chipping hammers and jackhammers to demolish the concrete topping slab of thebalconies followed by the plywood decking. Crew

Michael S. Plewacki, Principal/Facade Engineering Manager

Morrison Hershfield

By Michael S. Plewacki

For many in the facade community, lock-strip gasket facadesare often dismissed as a system to be removed and replacedwith modern aluminum curtain wall. While this may be practicalin certain situations, it is far from the only option available andnot always the right option for the owner’s budget or maintainingthe original architecture of a building.

Lock-strip facades continue to endure, but age has taken its tollon the functionality of what was once a revolutionary glazingsystem. By maintaining the lock-strip gasket facade and upgradingglazing when possible, building performance can be restored oreven increased as retrofit technology improves.

Remedial options are available for lock-strip gasket facades thatfocus on preserving and maintaining the primary elements andappearance of the system from simple remediation efforts, suchas the installation of exterior “wet-seals” to limit air and waterinfiltration, to complete replacement and reglazing. (Fig.1 and Fig. 2)

Improved curtain wall performance (reduced air infiltration,lowered solar heat gain and improved acoustical performance)

members created an efficient way tokeep debris to a minimum while theyworked. A trash chute was constructedto run through the scaffolding so theycould dump directly from the balconyto a wooden trash box at the bottomof the chute. The waste was emptiedregularly into dumpsters maintainingan orderly work site.

After demolition, Chamberlin repairedand replaced damaged framing andcolumns, as well as installing newthrough-wall flashing. Next, newwooden decking was installed withan eighth-of-an-inch drop per foot tocreate the proper drainage slope. Thena W.R. Grace Bituthene 3000 sheetwaterproofing system was appliedand covered with a Wausau paversystem. Finally, metal retaining flashingwas installed.

A NEW APPROACH

Each balcony included one or twocolumns consisting of four-inch steeltubes concealed with a decorativefiberglass cover. These columnsproved to be a challenge in accessingthe wooden decking beneath them. Thecrew utilized the column base plates toraise the steel tube so the plywood andframing could be replaced. In addition,some of the column base plates wererusted, so new steel plates were weldedand installed.

A larger challenge came when replacingthe columns that had been completelyremoved from the balconies. Thefiberglass covers were made of twopieces, which became warped whenremoved, therefore not matching upperfectly when reassembled. Crewmembers used Bondo to smooth outthe seam and imperfections on thecover before sanding, priming andpainting the columns. Since Chamberlinwas brought in mid-project, completeremoval of the columns and handrail oneach balcony was the system in placefrom the previous contractor. However,Chamberlin devised an alternatemethod for the deck replacement thatdid not require removing the columncovers or handrails. The crew memberssecured the columns in place byremoving only the ornamental base ofa column’s fiberglass cover. They thenremoved the eight-inch lag boltsconnecting the steel column to thecolumn base plate and underlyingframing members. Using those anchorpoints, they attached chains connectedto supporting I-beams that suspendedthe column’s weight, holding it in place.With this system, the crew couldremove the damaged wooden deckingsubstrate, as well as the column baseplate, and replace them while thecolumn remained intact. This systemnot only enhanced productivity forthe restoration process, but also

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(THE BUCKINGHAM Continued from pg. 1)

(LOCK-STRIP GASKET REPLACEMENT Continued from pg. 1)

ACTIVE MEMBER OF:

(Continued pg. 3...see THE BUCKINGHAM)

(Continued pg. 3...see LOCK-STRIP GASKET REPLACEMENT)

Balcony demolished to the framing before reconstruction.

Scaffolding system used to repair and replace damaged balconies atThe Buckingham.

Figure 1: Lock-strip gasket in need of repair. Photo courtesy of Chamberlin Roofing & Waterproofing.

incorporated an additional safety element withthe handrails in place during construction.

Chamberlin recognized the detailwaterproofing and flashing at the columnbase as another area where installation couldbe streamlined. Originally, a three-piece metaldesign was being used, but Chamberlindeveloped a method that only required twopieces and was easier to install. Each balconyand column on the property differed slightly inmeasurement, so there was not a one-size-fits-all piece for this task. Varying slopes andangles added to the difficulty. Each piece ofmetal had to be custom measured andfabricated by Chamberlin sheet metalmechanics. Reducing the number of piecesto be manufactured and installed by a thirdgreatly increased overall production, savingtime and money.

WEATHER CONCERNS

Extreme weather was experienced duringthis project as several storms tore throughHouston, including Hurricane Harvey. Foreach storm, Chamberlin shut down thejobsite following Chamberlin’s HurricanePreparedness SMART Plan: Secure, Monitor,Alert, Review and Team. These steps are putin place to create a safe environment for allinvolved and include securing equipment,trash, materials or other objects on the jobsite

that could be a potential hazard in high winds.Many of the Chamberlin crew members alsoutilized this protocol at their homes whenHurricane Harvey struck to keep safety asa top priority off the job with their families,as well.

At times, Chamberlin had up to 35 crewmembers working together to meet theproject’s schedule. Chamberlin WaterproofingSuperintendent Thomas Borrosco citesteamwork as the main contributing factor totheir success saying, “Chamberlin’s sheetmetal crew did an outstanding job throughoutthis project helping and supporting thewaterproofing team. Project ForemenFederico Castrejon and Losand Quinn alsoworked really well together, and with the crew,to make it a success for Chamberlin and forthe residents of The Buckingham.”

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(THE BUCKINGHAM Continued from pg. 2)

(Continued pg. 4...see LOCK-STRIP GASKET REPLACEMENT)

is achieved by introducing modern insulating glasswith a low-e coating and emerging technologies,such as vacuum insulating glass (VIG), and presentspossibilities for replacement of an original monolithicglazed system for increased energy performance.Reglazing also provides the opportunity to increasespandrel insulation or change the aesthetic of thefacade by introducing (or removing) existingspandrel panels.

While the benefits of the above are appealing,lock-strip gasket replacement projects are not immuneto challenges. As with most remediation projects,there are technical considerations to address.

INTRODUCTION

One of the first large scale lock-strip gasket glazingprojects was completed in 1952 at the General MotorsTechnical Center in Warren Michigan by Architect EeroSaarinen & Associates. In 2000 the building was listedon the National Register of Historic Places and in 2014it was designated a National Historic Landmark.

(LOCK-STRIP GASKET REPLACEMENT Continued from pg. 2)

Figure 2: Repaired lock-strip gasket. Photo courtesy of Chamberlin Roofing & Waterproofing.

Perimeter retainer metal protecting the waterproofingand pavers.

Chamberlin devised a hoist system to hold the columns in placewhile repairing the decking beneath.

In 1974 C.J. Parise made mention ofthis building’s facade system in his paper“Evaluation and Test of Lock-Strip GasketGlazing Systems” in the American Societyfor Testing and Materials (ASTM)Special Technical Publications 552 wherehe concluded:

“There have been many successful (lock-strip)installations in the past 20 years which arestill providing satisfactory service. Lock-stripgasket glazing is an excellent glazing system,but as true of any building system, there arecertain precautions which must be observedfor optimal performance.” (Parise et.al, 1974)

Although he did not live to see the GM TechCenter become a National Historic Landmark,his conclusion on this topic is as true today asit was in 1974 and concisely summarizes thewide range of challenges associatedwith working with lock-strip gasketglazing systems.

Since the 1974 article, the technology of thelock-strip gasket has largely remained thesame. However, modern lock-strip gasketdesigns have improved based upon earlyresearch and testing as well as improvementsin manufacturing technology. As industryprocesses and the body of technicalknowledge have evolved, so have thestandards governing the properties,installation and glazing of these systems.

Technical standards are well documentedand are a readily accessible resource to gainperspective where the “experience factor” ofsomeone who has specific working knowledgeof these systems, such as C.J. Parise in the1970s and those like him of that era, becomesless available.

To effectively remediate and replace lock-stripgasket systems, a team must understand notonly the applicable standards but also thelessons learned and documented by product

manufacturers and those with experience iflock-strip glazed buildings are to stay relevantin our time.

BACKGROUND

Lock-strip gaskets or “zipper gaskets” aregenerally described as a two-part neoprenegasket assembly consisting of a main bodygasket, which is used to capture and supportthe glazed infill, and a lock-strip or “zipper”that is inserted into a receiving channel onthe main body gasket to provide compressionbetween the main body gasket, glazing infilland framing. Lock-strip gaskets provide acomplete thermal break from the frame ofthe building and glass to assist in providingan efficient envelope. With no exposed metal,the systems provide exceptional condensationcontrol as well as exceptional vibration andnoise dampening (Griffith Rubber Mills, 2010).

Remediation of a lock-strip gasket curtain wallsystem, including removal and replacement ofthe lock-strip gasket curtain wall and glazing,is an option for consideration in many caseswhere preservation of the building facadeis desired.

In such cases, it is likely the lock-strip gasketwill require full replacement due to the existingcondition of the gasket material. This ishighly dependent on the age and exposureof the materials, but the majority of projectsconsidering reglazing have aged to the pointwhere replacement is a prerequisite.However, there are times when this maynot be necessary and a waterproofingremediation can be undertaken.

During a reglaze and gasket replacementproject, there is an opportunity for theexisting aluminum framing system seals(internal/perimeter), as well as coatings, to berestored and the system structurally modifiedto accept modern high performance glass.

Improvements may include dual-panedinsulating glazing unit (IGU) as infill, as well asincreased spandrel insulation. The aestheticof the facade can be altered by introducing(or removing) metal spandrel panels. As thetechnology becomes more commerciallyviable, there is the opportunity to reglaze withvacuum insulating glass (VIG) for projectswhere the modification of a monolithic glazedsystem is prohibitive and increased energyperformance is desired.

Introducing a new lock-strip gasket systemto an aged facade with modern low-e coatedinsulating glass can provide additional visiblelight transmittance, lower solar heat gain andimproved sound transmittance (OITC andSTC) performance. This all translates toincreased interior occupant comfort andsafety, as well as energy savings.

4

(LOCK-STRIP GASKET REPLACEMENT Continued from pg. 3)

Figure 4: Silicone sheet overlay and wet seal accessories. Diagram courtesy of Tremco Commercial Sealants.

Figure 5: Lock-strip gasket support for IGU glazing. Image courtesyof Griffith Rubber Mills, Stanlock Catalog 2010.

Figure 3: Retaining clips for lock-strip gasket. Diagram andimage courtesy of Griffith Rubber Mills. (Continued pg. 5

...see LOCK-STRIP GASKET REPLACEMENT)

Figure 6:Weep strategies for lock-strip gasket with insulatingglass. Diagram courtesy of ASTM C964.

A Setting blocks at 1/4 points

B Weepholes not covered by setting blocks(center between and on each side of blocks near jambs)

C Weepholes in frame

D Open-cell polyurethane pad behind each weephole in frame

E 6.4 mm (1/4 in.) minimum clearance when pad is in line with weephole above

MOST ACCEPTABLEMETHOD

LEAST ACCEPTABLEMETHOD

ACCEPTABLEMETHOD

A

B

C

E

D

B

A

Chamberlin Roofing & Waterproofing’sbalcony repair and replacement for TheDriskill Hotel in Austin, Texas, wasawarded an ENR Texas & Louisiana BestProject Award of Merit. This programrecognizes the top construction projectsin their region and the companies whodesigned and built them. A panel ofindustry experts evaluates the projects onmany criteria, including safety, innovationand teamwork. Additionally, Chamberlin isa proud team member of nearly a dozenother ENR-award-winning projects thisyear. From airports to aquatic centers,projects of all types swept first and secondplaces in the Best Projects competition.Chamberlin is honored to have beeninvolved with excellent partners deliveringthose successful projects to our clients.

Established in 1989, ABC’s Safety TrainingEvaluation Process (STEP) was developedand written by contractors, for contractors.Participating ABC member firms measuretheir safety processes and policies on20 key components through a detailedquestionnaire with the goal ofimplementing or enhancing safetyprograms that reduce jobsite incidentrates. ABC believes world-class safetyprograms have three main components: acommitment from company leadership toembrace safety as the core value uponwhich decisions are made, a top-to-bottomsafety culture that empowers allemployees to create the safest workenvironment possible and systems and

processes that focus on how to preventa hazard or incident from occurring.Chamberlin Roofing & Waterproofingachieved ABC STEP Platinum statusin 2017.

Chamberlin Roofing & Waterproofing wonfirst place in TEXO’s 2017 DistinguishedBuilding Awards competition in the OtherSpecialty Construction category for theirmassive waterproofing scope at TheStar in Frisco, Texas. The DistinguishedBuilding Awards embody the skill,commitment and passion that TEXOmembers have for construction. Placingfirst qualifies Chamberlin for ABC’sNational Excellence in ConstructionAwards competition.

5

(LOCK-STRIP GASKET REPLACEMENT Continued from pg. 4)

LOCK-STRIP GASKET REMEDIATION

As previously mentioned, remediation of alock-strip glazing system should include anevaluation of the current physical conditionfor structural performance, as well asan evaluation of air and water infiltration.Depending on the findings of thisevaluation, a remediation of the existinglock-strip gaskets could be considered tomaintain the serviceability of the facade.

There are several elements of a lock-stripgasket system remediation that may beconsidered to extend the serviceability ofthe existing glazing system. Generally, aremedial program will employ a strategy ofmechanical stabilization and preservationof the existing gasket, as well as a meansof reducing air and water infiltration.

REINFORCEMENT CLIPS

To provide structural support of theexisting system, a remediation may includeinstallation of retaining clips at exteriorhorizontal and vertical lock-strip gaskets.The addition of mechanically attached

retaining clips will help to ensure structuralperformance of the system as deterioratedgaskets may not exhibit the sameperformance characteristics as originallydesigned. This is especially important atcorner zones and locations anticipated tohave significant wind exposure. (Fig. 3)

The use of reinforcement clips results inan increase in the resistance of the gasketto roll off the frame. The use of one clip perside provides substantially higher loadcapacity and still greater capacity isobtained using two clips per side.

Depending on the gasket and frame profile,several reinforcement clip options areavailable. The majority of applicationsrequire an exterior installation, but interiorclips are used for some systems toaugment exterior clips.

The project-specific reinforcementrequirements for the lock-strip gasketsystem should be designed by aProfessional Engineer with experiencein facade engineering evaluations. Theengineer will be able to determine the

number of clips and spacing requirementsas well as evaluate the profile of the clipto ensure glass to metal contact isavoided. The clip design strategy canthen be coordinated with any remedialwaterproofing work.

SEALANTS

To provide reduced air infiltration andincreased water penetration resistance,an aged lock-strip gasket system may besealed along the exterior of the gasket.This work generally includes installationof new silicone “wet seals” between thelock-strip gasket and the exterior glass

Industry Honors

To continue reading article, visit:https://www.chamberlinltd.com/articles/

lockstrip-gasket-replacement-remediation-strategies/

Michael Plewacki joined Morrison Hershfield in2014 and currently serves as Principal/FacadeEngineering Manager. Morrison Hershfieldprovides integrated solutions to residential,institutional, industrial and commercial clientswho require reliable and cost-effective systems inboth new and retrofit facilities. The combinedskills of their engineers, architects, techniciansand support personnel with diverse backgrounds indesign and construction provide clients with a teamrecognized as leaders in the field of building science.

Mr. Plewacki can be reached atmplewacki@morrisonhershfield.com

ENR Texas & Louisiana presented Chamberlin a Best ProjectAward of Merit for their balcony repair and replacement atThe Driskill Hotel in Austin, Texas.

Chamberlin’s safety program was recognized with ABC STEPPlatinum status for 2017.

Chamberlin Roofing & Waterproofing received a 2017 TEXODistinguished Building Award for their work on the DallasCowboys World Headquarters and The Ford Center inFrisco, Texas.

PROjeCTS In PROGReSS

LOCaTIOnS:

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

HOUSTOn

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OkLaHOma CITY

aUSTIn

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

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

2755 Business Park DriveBuda, TX 78610Ph. (512) 275-1600Fax (512) 523-9350

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

Also 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.

TEXAS STATE UNIVERSITY ENGINEERING ANDSCIENCE BUILDING – SAN MARCOS, TX

new Construction waterproofingContract Amount: $1,800,000 (approx.)Owner: Texas State University SystemArchitect: TreanorHL and Alamo ArchitectsGeneral Contractor: SpawGlassScope of Work: Installation of below-grade waterproofing, hot fluid-applied waterproofing, expansion joints, water repellents, thermal insulation, fluid-applied membrane air barrier, sheet metal flashing and trim, joint sealants, pavers and pedestals, dampproofing and green roof systemProject Description: Higher education Engineering and Science Building

WELLS FARGO PLAZA BUILDING – BRYAN, TXRemedial waterproofingContract Amount: $350,000 (approx.)Owner: Kensington Management, LLCConsultant: Chamblee and AssociatesGeneral Contractor: Chamberlin Roofing & WaterproofingScope of Work: Brick replacement, tuck pointing, wet sealing, waterproofing of brick and concrete fascia, power washing and replacement of door and window caulk perimeters and masonry jointsProject Description: Repair and restoration of six-story bank and office building

CHRISTUS SPOHN SHORELINE HOSPITAL – CORPUS CHRISTI, TX

new Construction Roofing Contract Amount: $2,200,000 (approx.)Owner: CHRISTUS SpohnArchitect: Perkins + WillGeneral Contractor: McCarthy Building Companies, Inc.Scope of Work: Installation of TPO roofing system, sheet metal flashing and trimProject Description: Hospital expansion

UTMB PARKING INITIATIVES – LEAGUE CITY, TXnew Construction waterproofing Contract Amount: $600,000 (approx.)Owner: UTMB Health League CityArchitect: Kirksey Architects, Inc. General Contractor: Hensel PhelpsScope of Work: Installation of below-grade waterproofing, elevator pit waterproofing, fluid-applied waterproofing, traffic coating, insulation, joint sealants, expansion joints, air barrier, sheet metal flashing and site sealantsProject Description: Parking garage, pedestrian bridge and three-story building

HIBISCUS RESTAURANT – DALLAS, TXRemedial RoofingContract Amount: $150,000 (approx.)Owner: Potter Investments, Ltd.General Contractor: Chamberlin Roofing & WaterproofingScope of Work: Removal of existing roof system and installation of modified bitumen roofing, TPO roofing, flashing and sheet metalProject Description: Upscale eatery

San anTOnIO13111 Lookout RunSan Antonio, TX 78233 Ph. (210) 822-6536Fax (210) 822-8211

ASHFORD OAKS – SAN ANTONIO, TXRemedial waterproofing   Contract Amount: $300,000 (approx.)Owner: Woodside Capital PartnersGeneral Contractor: TranswesternScope of Work: Wet glazing and replacement of granite control jointsProject Description: Repair and renovation of 200,000-square-foot office building

DEVON ENERGY CENTER CONNECTOR – OKLAHOMA CITY, OK

new Construction waterproofingContract Amount: $100,000 (approx.)Owner: Devon HeadquartersArchitect: Kendall/Heaton Associates, Inc.General Contractor: JE Dunn Construction CompanyScope of Work: Installation of hot-fluid rubberized asphalt waterproofing, vehicular traffic coatings, sheet metal flashing and trim, roof pavers and expansion controlProject Description: Fifty-story corporate skyscraper

KATY STATION – DALLAS, TXnew Construction Roofing and waterproofingContract Amount: $2,600,000 (approx.)Owner: Genesis Katy LP/Gordon LPArchitect: EDI International, Inc.General Contractor: Andres ConstructionScope of Work: Installation of dampproofing, hot-fluid rubberized asphalt waterproofing, sheet waterproofing, fluid-applied waterproofing, pedestrian and vehicular traffic coatings, roof and deck insulation, fluid-applied air barrier, roof pavers, firestopping, joint sealants, expansion control, TPO roofing system, sheet metal, flashing and counterflashingProject Description: High-rise luxury apartments

GALLOGLY HALL ACADEMIC BUILDING – NORMAN, OKnew Construction waterproofing Contract Amount: $250,000 (approx.)Owner: The Board of Regents of the University of OklahomaArchitect: Page Southerland Page, LLPGeneral Contractor: JE Dunn Construction CompanyScope of Work: Installation of hot-fluid rubberized asphalt waterproofing, bentonite waterproofing, fluid-applied air barrier, site and paving sealants, roof pavers and joint sealantsProject Description: Biomedical Engineering learning facility

FROST TOWER – SAN ANTONIO, TXnew Construction waterproofing Contract Amount: $800,000 (approx.)Owner: Weston Urban and Frost Bank, a joint ventureArchitect: Pelli Clarke Pelli ArchitectsGeneral Contractor: Clark ConstructionScope of Work: Installation of below-grade waterproofing, insulation, elastomeric coating, hot-applied waterproofing, traffic coating, expansion joints and joint sealantsProject Description: Twenty three-story office building and bank headquarters