Building Envelope Articles

Waterproofing Crew Earns Top Grade for School Expansion

Photos courtesy of Alamo Waterproofing
Vendor Team

Alamo Waterproofing
Coatings contractor
4600 Boldt Rd.
San Antonio, TX 78222
(210) 648-2100

Atonement Academy
Coatings client
15415 Red Robin Rd.
San Antonio, TX 78255
(210) 944-4093

Material manufacturer
2626 S Sheridan St.
Wichita, KS 67217
(316) 945-9328

Equipment manufacturer
P.O. Box 97030
Redmond, WA 98073
(800) 536-1800

H&E Equipment Services
Equipment supplier
7500 Pecue Ln.
Baton Rouge, LA 70809
(888) 200-0943

STS Coatings, Inc.
Coatings manufacturer
347 Hwy. 289
Comfort, TX 78013
(830) 995-5177

The Atonement Academy first opened its doors in 1994 in San Antonio, Texas, with an initial enrollment of just 62 children in kindergarten through third grade. As the years progressed, the Catholic school’s popularity surged, prompting its leaders to eventually expand to a curriculum of pre-kindergarten all the way through high school.

Today, the school’s total enrollment is more than 500 students — nearly 10 times the volume of when it first opened nearly 25 years ago. That rapid expansion quickly made the Atonement Academy’s original facilities insufficient, thus incentivizing the school to authorize the construction of two new buildings for its students.

“It was truly a ground-up construction project,” said Brandon Wilson, president of locally based Alamo Waterproofing. The coatings contractor, selected by general contractor Keller-Martin Construction, Inc. to waterproof the gypsum and concrete masonry walls with an air and water barrier solution, had a crew of three to four workers regularly on site for the 18-month project throughout 2016 and early 2017.

High School

Since the 35,000-square-foot (3,251.6 m2) project involved primarily new construction, the condition of the substrate proved worthy of a “high grade,” requiring only minimal surface preparation to ensure a clean, dry substrate for proper system adhesion. But for the waterproofing crew to ultimately pass its own test, one of the biggest challenges each day was simply accessing the various parts of the jobsite — particularly the elevated areas.

“Those were two big towers,” Wilson recalled. “The towers were over 80 feet [24.4 m] in the air and hard to access. We had to use aerial platform lifts to reach the peak.”

The use of Genie lifts, rented from H&E Equipment, also required additional personal protective equipment (PPE) for the crew. In addition to the company’s usual jobsite standards of work boots, safety glasses approved by the U.S. Occupational Safety and Health Administration (OSHA), hard hats, and a hi-vis vest or shirt, crew members wore fall protection harnesses when utilizing the aerial lifts.

The lifts also proved helpful because they eliminated any potential conflicts between the coatings contractor and other trades. “We wanted it so that the mason can work without us in his way, and without him in our way,” Wilson explained. “That way, there’s not a whole lot of confusion working together on a scaffolding. We basically just follow them until we get it completed. They get a portion ready at a time, and then they’re onto the next section, and we do the same thing.”

Four-Part Test

With an access and logistics plan in place, the waterproofing crew moved in sections to coat the walls. They scheduled the job in four parts, and first on the agenda was putting down the GreatSeal LT-100 Liquid Tape from coatings manufacturer STS Coatings, Inc., applied with a caulking gun.

“The first thing we would do, after they got the drywall up, is apply the LT-100 GreatSeal to the sheathing joints and fasteners,” Wilson explained. With a distinctive blue color to enable visual verification, the elastomeric seam sealer — applied in a 0.25-inch (0.64 cm) bead — is designed to keep the structure watertight until the air barrier system is installed.

While sheathing joints and fasteners received the blue liquid tape, window and door frames were wrapped with STS’ black UT-40 Universal Tape, described as a self-adhering air and moisture barrier tape for use on vertical and horizontal substrates. Before putting down the tape, crew members first applied the corresponding AP-42 High Tack Acrylic Primer to ensure proper adhesion.

“The exact thickness for the primer doesn’t matter, you just need good coverage,” Wilson said. “Basically, anything that’s getting UT-40 over the top, there needs to be a solid primer behind.” Both the primer and the UT-40 were applied using a weighted steel roller, with the total UT-40 system thickness averaging 40 mils (1,016.0 microns).

With the liquid and universal tape installed over specialized areas, the third step was to apply the Wall Guardian FW-100-A air and water barrier. The acrylic-based, liquid-applied, elastomeric barrier is normally applied using spray equipment, but that wasn’t an option on this jobsite due to concerns with overspray.

“There’s kind of a wind tunnel that forms between the two buildings,” Wilson explained. “Because of that wind blowing between the two buildings, and once they got a little bit of masonry up, we couldn’t spray because it would’ve gotten on the masonry.”

As a result, the crew applied the FW-100-A using 9-inch (22.9 cm) roller frames at an application rate of ~2.5 gallons (9.5 L) per 100 square feet (9.3 m2). They were seeking an average wet film thickness of 40 mils (1,016.0 microns). While spraying the air barrier at this thickness could usually be accomplished in a single pass, roller application required two coats to achieve the desired thickness. That added to the job’s timetable.

Once the air barrier was installed, the fourth and final step was to apply 3-ounce (88.7 mL) copper through wall flashings in specialized areas such as the base lug, window heads and sills, and door heads. “You put that on these buildings to divert any water that gets into the cavity wall out,” Wilson explained. “It goes on window heads, window sills, low roofs, things like that.”

Generally speaking, each crew member was responsible for one or two of the four steps in a given area. “We typically would have one guy applying the air barrier, maybe another providing the LT-100 GreatSeal ahead of the guy applying the air barrier, and then behind the air-barrier guy, we have a man putting on the through-all flashing.”

For extra credit, the Alamo crew even installed pre-formed Balco seismic expansion joints in the new masonry.

Passed With Flying Colors

It was a slow and methodical process for the crew over the course of a year and a half. That was particularly the case in winter months when crew members would occasionally have to wait for temperatures to rise to 40 °F (4.4 °C) to ensure a suitable working window for the water-borne materials.

But the job ultimately finished on time and on budget, allowing the expanded Atonement Academy to open its doors in August 2017. For its part, Alamo Waterproofing appears satisfied with its grade from the client.

“As far as I know, everybody was really happy,” Wilson said. “We didn’t have any issues out there, so as far as I know, we did a good job. We go out there, get it done, and it’s on to the next one.”

For the growing school, the installation of this crew’s barrier is removing a potential barrier to a positive learning environment. That should certainly give Alamo an ‘A’ for this project!

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