Side Story: Case Study – Mason Finds Win-Win Solution for CVS Store
Joe Montalvo, who owns Montalvo’s Masonry, in Ft. Worth, Texas, was understandably pleased when he won the masonry bid for a new CVS Pharmacy in Midwest City, Okla. By some measures, CVS is the nation’s largest chain of retail pharmacies.
The architects, Carter & Burgess of Ft. Worth (later acquired by Jacobs Engineering Group Inc.), had specified a reddish-colored, split-face, eight-inch CMU for much of the new store’s single-wythe exterior walls.
The specified flashing method was to be “step-flashing.” In step-flashing, the flashed course requires two wythes of half-width block, allowing the flashing membrane to be installed between them in a “Z” configuration.
Step-flashing often is used for flashing single-wythe CMU. But Montalvo knew it would eat up massive amounts of time and labor.
Eager to save time, Montalvo discussed alternatives with the architect. What if he solid-grouted the first course of eight-inch block, he asked, and inserted cotton rope for drainage? The architect nixed that idea. Flashing had to be installed for more reliable moisture control and greater wall longevity.
Resigned to using the tedious step-flashing, Montalvo got ready to order the two sizes of architectural block.
But first, he attended a product demonstration, held at Builders Equipment & Supply in Ft. Worth. A representative from Mortar Net USA in Burns Harbor, Ind., gave demos of two of the company’s products. One of them was its newly redesigned CMU-flashing system, Blok-Flash.
A CMU-flashing system? Montalvo’s ears perked up.
The Blok-Flash system, he learned, featured lightweight, high-density polyethylene pans that simply could be dropped onto each block of the first above-grade course, and then mortared in place. The pans would intercept moisture that flowed down through the vertical cores, and then expel it to the building’s exterior through built-in Weep Spouts.
He was especially happy, though, to hear that Blok-Flash eliminated the need for multiple sizes of architectural block. This would not only help him save time, but also it would avoid the problem of getting a bad color match between the two lots. Moreover, the product could be used wherever flashing was required — above windows, doorways, bond beams, etc. Its built-in Weep Spout also made a separate drip-edge unnecessary.
It made pea-gravel unnecessary, too. The system included feather-light rectangles of tough, polyester-mesh fabric (Drainage Mattes) that could be slipped quickly into cores of the next course of block above the Blok-Flash, to direct moisture to the built-in weeps and protect them from falling mortar.
The manufacturer’s rep asserted that using Blok-Flash not only would save in set-up and material costs, but also could save 50 percent or more in labor costs versus step-flashing.
After the demonstration, Montalvo knew this was the answer he’d been looking for. But would it fly with the architect?
Another lucky break awaited him. “I submitted a substitution request to the general contractor and the architect,” he says, “and it was immediately approved.” Apparently, the CVS architects were already familiar with Blok-Flash, and may have been moving toward it for future stores.
On the job site, Montalvo’s workers needed little training to pick up the new system. The Blok-Flash went in swiftly, and the men found that tucking Drainage Mattes into the next course of block was far faster than hauling and pouring heavy pea-gravel.
As promised, the savings added up at equal speed. “There’s no question it saved time and money,” Montalvo said. “It was the best thing since sliced bread!”
- 44The flashing and drainage plane has always been a critical component of any cavity wall system, diverting moisture outward as it collects in the cavity space to the exterior of the façade through the weep openings. A failure in this arrangement can ultimately lead to degradation of wall components including…