Concrete Coatings Articles

Waterproofing the New Glassell School of Art Campus

Photos courtesy of Chamberlin Roofing & Waterproofing
Vendor Team

A&A Melters
Equipment manufacturer
Coquitlam, BC, Canada
(888) 469-4480

Chamberlin Roofing & Waterproofing
Coatings contractor
Houston, TX
(713) 880-1432

The Glassell School of Art
Coatings client
Houston, TX
(713) 639-7500

Coatings manufacturer
Canton, MA
(800) 576-2358

Coatings manufacturer
Beachwood, OH
(800) 321-7906
FB: TremcoSealants

The Glassell School of Art has been part of The Museum of Fine Arts, Houston (Texas) since its founding in the late 1920s. In May 2018, the school opened its new home in the form of an L-shaped, 93,000-square-foot (8,640.0 m2) building that, for the first time, houses all its students under one roof, whether they are in the Junior School, the Studio School, or the Core Program.

The new Glassell building is double the school’s previous size, and it now includes a sprawling plaza and a sloping, walkable green roof offering dramatic views of the campus. The green roof landscaping system, along with a pergola, an amphitheater, an underground parking garage, and the plaza featuring a fountain, required several different types of waterproofing. Chamberlin Roofing & Waterproofing, a regional contractor serving Texas, Oklahoma, Louisiana, and New Mexico, performed both roofing and waterproofing scopes for this project. And the amount of penetrations and tie-ins, not to mention design changes along the way, turned Chamberlin’s handiwork into almost a work of art in itself.

Jobsite Traffic Jam

With nearly 20 trades working on the Glassell school, coordination and communication were crucial. “This was a very congested project site, and crew members were cognizant of potential hazards,” said Allen Polasek, Chamberlin’s senior project manager — waterproofing and caulking in Houston. The project required “a lot of coordination with there being other trades,” he added.

Over the course of the two-year job, Chamberlin brought to the site up to 20 waterproofing technicians and eight roofing technicians from the Houston office, making for a grand total of 27,606 Chamberlin man-hours.

Both a site-specific safety plan and a job hazard analysis were developed in advance. And Chamberlin’s zero-tolerance fall protection policy was in place throughout the job. Appropriate personal protective equipment (PPE) included hard hats, safety vests, safety glasses, and gloves. In addition, long sleeves were worn when working with the hot fluid-applied waterproofing, and the kettle operator wore a face shield, apron, and leather gloves.

From the Bottom Up

Chamberlin’s work began in the below-grade parking garage, where crew members installed a Tremco Vulkem 350/950NF/951NF traffic coating system, expansion joints, and more than 170,000 square feet (15,793.5 m2) of Tremco Paraseal bentonite waterproofing. The new concrete in the garage was pressure washed with a 5,000-psi (34.5 MPa) pressure washer and prepared to an International Concrete Repair Institute (ICRI) concrete surface profile (CSP) of 2–4.

The Vulkem traffic coating system consists of the 350 Base Coat, an elastomeric waterproofing membrane; the 950NF Wear Coat, a low-odor, high-solids polyurethane; and the 951NF Top Coat, a two-part, aliphatic, high-solids polyurethane providing a chemical- and ultraviolet-resistant weatherproof wear surface. All layers of the system were applied with squeegees and backrollers — the 350 to ~25 mils (635.0 microns) wet film thickness (WFT) and the 950 and 951 to ~12 mils (304.8 microns) WFT each.

According to Polasek, groundwater was a challenge while installing the bentonite at the garage slab. “In order to get our membrane down,” he recalled, “it was a struggle because there was constantly water coming in. But we finally managed to do it. They [the general contractor] had to keep adding more zones to pump water out. ...But finally, they got it done, and we were able to put our membrane down.”

More Than Meets the Eye

In addition to the waterproofing and traffic coating in the parking garage, Chamberlin installed more than 20,000 square feet (1,858.1 m2) of hot fluid-applied waterproofing underneath the green roof landscaping system and amphitheater. The plaza received nearly 50,000 square feet (4,645.2 m2) of hot and cold fluid-applied waterproofing plus site sealants. Chamberlin also installed more than 9,000 linear feet (2,743.2 m) of exterior joint sealants, in addition to water repellent, on the building’s precast panels. The elastomeric coating was installed on the central plant portion of the building, which also received a Sika Sarnafil PVC (polyvinyl chloride) roofing system, sheet metal flashing, and trim.

“The majority of the work was the hot,” said Polasek, referring to Tremco’s TREMproof 6100 hot fluid-applied waterproofing. “That was probably the most interesting part of it. The cold-applied was used… for the plaza deck, and that’s about it as far as the cold goes. We did use a bunch of urethane traffic coatings in mechanical rooms and traffic areas in the garage that are above occupied spaces. …But the most interesting part’s the hot roof.”

The roof was cleaned and prepared to a CSP of 3–4. A double-jacketed oil-bath melter with mechanical agitation — aka a kettle — was used to heat the waterproofing liquid. The kettle itself was lifted and moved as needed with a crane manufactured by A&A Melters.

Two coats of hot fluid-applied waterproofing were applied with squeegees and backrollers at 90–125 mils (2,286.0–3,175.0 microns) WFT, with a reinforcing fabric installed between them. Total thickness of the 6100 system was ~215 mils (5,461.0 microns).

The green roof design specified multiple variations within the waterproofing systems. Some sections needed root barrier, while some did not. Instead of covering the roof in one roofing or waterproofing system, as is often the case, Chamberlin crew members diligently followed the designs and specifications to create a green roof consisting of multiple systems. “There’s actually some hot applied on that plaza deck, as well,” said Polasek. “Like half hot applied, half cold applied. It’s really chopped up and random.”

The cold-applied system Polasek referred to is Tremco’s TREMproof 250 GC, which went down at a minimum of 60 mils (1,524.0 microns). Again, all surfaces were initially pressure washed, and the coatings were applied by squeegee and backroller.

“We had several different subs involved in the green roof,” Polasek continued. “It was a Tremco green roof system, but we only provided the hot fluid-applied waterproofing system and the insulation. The landscaper provided the plants and the mulch and the plumbing and all that.”

Chamberlin had to consider the tie-in conditions of their various scopes as well. For example, to tie the hot fluid-applied waterproofing into the cold-applied fountain waterproofing, Chamberlin had to coordinate with the fountain contractor, the utilities subcontractor, and the mechanical subcontractor for an optimum workflow.

The Art of Change

With so many trades to work around and so many different aspects of the job scope, Chamberlin’s crew was also ready to tackle the design changes that occurred along the way. “It wasn’t called a design-build job,” Polasek said, “but you could kind of consider it that because there were all types of design changes throughout the whole project. Nothing too substantial, but just random changes here and there constantly.”

The crew also had to work some random weekends — “just if we needed to catch up on something or get something complete,” per Polasek. “Sometimes we did work in the evenings… for our cold applied waterproofing” because the falling temperatures helped to reduce outgassing, he noted.

Overall, Polasek viewed this job as “a cool, very interesting project.” He said, “It was just a very long project. …There’s a lot of weird stuff on it.” But Chamberlin has already begun working on more waterproofing jobs on the campus — something Polasek referred to as “Phase 2.”

Chamberlin sealed the Glassell School of Art’s new building and plaza watertight, leaving a space for Houstonians to access performing arts and education for years to come.

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