Volume 16, Issue 6 - August/September 2015



Are You Doing It Wrong?

by Trey Barrineau

Flashing plays a vital role in preventing water infiltration around doors and windows, and the products available today are much more versatile and dependable than in years past.

Despite that, many builders still don’t understand the importance of flashing—and experts say a shocking number of them aren’t installing it correctly.

As the door and window industry continues to recover from the Great Recession, the demand for flashing products is bouncing back as well. Principia Consulting reports that the $2.1 billion market is expected to grow an average of 6 percent each year through 2017.

However, Principia’s survey of builders and contractors also found that getting accurate information about products and performance was one of the biggest challenges faced by respondents.

Education Means Everything

That’s been a huge issue encountered by Brendan Welch of Parksite, a sales, marketing and distribution company that serves the building products industry. He says that lack of information can have costly implications.

“Probably 60 percent of builders don’t understand the proper installation techniques for flashing,” Welch says. “If you have 100 different windows from 100 different builders, you’re going to have 60 to 70 windows that aren’t properly flashed.”

That leads to callbacks and expensive repairs or replacements.

“The majority of the windows that we replace were not properly flashed,” says John Azeri of Nationwide Windows in Paterson, N.J. “If you don’t have a qualified contractor installing windows, you could have major problems later on.” Welch says a big problem is installers who don’t want to learn new techniques.

“Most window and door manufacturers require a particular application,” he says. “A lot of builders are very set in their ways, so to get them to move over to a different type of technique or, more accurately, science-tested techniques, it’s sometimes like twisting an arm.”

For example, Welch says a large number of builders use modified bitumen flashing tape, also called asphalt-infused tape, because it’s relatively inexpensive. But many manufacturers of vinyl windows say that tape can’t be used with their products because it can have a negative chemical reaction with vinyl, ultimately causing the weatherproof seal to deteriorate.

“Marvin, for example, says if you use asphalt-impregnated tape on their products, you void the warranty on the window,” Welch says. “I go to a builder and he says ‘I’ve been using that tape for 20 years.’ Well, have you been back to check those windows in the past 20 years? If the warning’s out there, why would you put it on?” However, Welch says he’s also seen a lot of contractors who are willing to learn new things—and part of that is being driven by increasingly tougher energy codes.

Changes to building codes might be making installs better, too.

“I also think the other thing that’s pushing them to use these installation techniques properly are the new energy codes,” he says. “These run parallel to both flashing and the house wraps themselves.”

In April, two American Architec-tural Manufacturers Association (AAMA) voluntary standards regarding flashing were added into the International Building Code (IBC), signifying the growing importance of flashing to prevent water intrusion.

AAMA also offers training in flashing installation via its InstallationMasters program.

“Education is very important,” says Azeri, who is an Installation Masters instructor. “My advice to a homeowner is make sure your contractors are trained.”

Bend Me, Shape Me

As far as trends in flashing products, Welch says the key word is flexibility—as in flexible tape that can prevent water intrusion around any door and window configuration. (Flashing tapes of all kinds make up more than 90 percent of the market, according to Tony Reis, the sales and marketing director for MFM Building Products.)

“Flexible adhesive tape is extremely easy to use, and it’s dependable,” says Azeri.

“It allows you to install it without caulking to seal the flashing over.”

Dupont’s FlexWrap, introduced in 2001, features a butyl-based adhesive and can be easily stretched and wrapped into an opening before the window is installed.

“That allows you to flash along the bottom of the window,” says Welch. “You can bend it and press it to the outside wall without making a cut, because it’s a flexible tape. It adheres to the wall, so there’s not going to be any extra penetrations there. It’s a unique application.”

Flexible flashing tape is also perfect for odd-shaped openings, Welch says.

“Say you have an arch top or a circle window,” he says. “You can’t take a straight flash and bend it around those types of windows to flash it out.”

Despite its relatively high cost, Welch says flexible tape is a trend that’s not going away.

“It’s very possible that this could become the industry standard in the next few years,” he says.

Reis says today’s tapes are sticker than they were in the past.

“I think everyone’s gotten better with adhesion,” he says. “Our product is a lot better than it was 10 years ago. We hardly ever get a complaint about adhesion.”

The ability to use the products in low temperatures is also important. Reis says MFM’s new Powerbond adhesive can be applied at temperatures as low as 25 degrees Fahrenheit.

Installation Advice

If you’re ever at a window-installation job with John Azeri of Nationwide Windows in Paterson, N.J., he says you’ll hear one phrase a lot:

“Weatherboard fashion.”

That means always install the flashing around a window from the bottom up. That way, when water hits it, it runs off the bottom portion of your flashing.

“It’s extremely crucial,” Azeri says.

“Overlapping your existing flashing pieces from the bottom working your way up directs the water off of it instead of going behind it.”

Flashing carefully around the top and bottom of a window opening is important as well. Missteps at this point in the job can create a lot of problems.

“What you’ll see is mostly on the bottom flange of the window,” says David Delcoma of MFM Building Products. “People will tape right over top of that. You have to waterproof the sill before you put the window in. Then you put the window in so if any water does get in there, it has a way to weep out. If you stick that window in and tape all four sides of it, there’s no place for that water to go. And we will see that a lot.”

Another problem is flashing the header at the top.

“You have to cut back your house wrap, and your tape should be on the substrate,” says Tony Reis of MFM Building Products. “I’ve seen it many times where they just go over the house wrap, and that’s it. Any moisture that’s coming in back of the house wrap is going right into the window. That is the biggest no-no. You’re making a funnel.”

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