December, 2006

Selling Smarter: Millwork

Waterproof Windows and Doors

By Gary Katz

When I started out as a contractor, I thought the first few calls I got at night were kind of neat. People were calling me at 9 p.m. or 10 p.m., or even at 7 a.m. on a Sunday to help fix a problem. That made me feel pretty important. For about two weeks.

In our business there is nothing more dreaded than callbacks, especially ones that threaten mold and litigation. And no product installation causes more grief both to sales and installed sales programs than windows and doors. But why—especially when we all know that installing windows and doors isn’t rocket science?

I’ve heard the problem blamed on the lack of skilled workers, the shortage of schools and apprenticeship programs, the absence of proper job site supervision. Sure, all of those reasons are part of the problem, but they all fall within the scope of the real reason: poor communication. And we’re all at fault there.

If your yard hasn’t started a training program, and I mean devoted specific space and manpower for a classroom, do it today. That’s the first step toward improving communication. The second is establishing regular training seminars for your contractors, counter sales, outside sales, and installed sales employees and independents. How do you ensure attendance? Simple. Offer certification programs and discounts for certified installers. And no subject is better suited to a classroom seminar environment that installing windows and doors.

Use a cant strip and sill pan

There are two approaches to window and door installation: The Barrier System—where installers believe they can defeat nature with caulking; and The Drainage System—where installers accept that all windows and doors will leak eventually and plan accordingly. Installing a sill pan is the first step in The Drainage System: it begins with a cant strip. Installing a sill pan without a cant strip is like pouring a patio without any pitch for drainage. Beveled siding makes a perfect cant strip. To ensure that water won’t penetrate the home, add a dam on the back of the cant strip, before installing the sill pan. Cant strips require an additional 1/2- to 3/4-in. rough-opening height, so be sure to frame your openings taller. And when using a cant strip, always place reversed shims on top of the sill pan, before installing the window, so that the window is properly supported by a level surface.

Membrane sill pans

On a wood subfloor, tack the cant strip in place with nails or screws; on a concrete slab, set the cant strip in a bed of adhesive caulk. Next, install the membrane pan. Start by placing patches in each corner. Roll the membrane out across the opening, removing only a small amount of release paper at a time, beginning 6-in. to 8-in. up one jamb leg. For a tight seal, make a small cut in each corner and lap the pan membrane over the corner patches, shingle style.

Site-built sill pans

Traditionally, sill pans have been made from sheet metal or copper coil stock using a brake, and for custom homes, copper is still the best answer. Vinyl or pvc coil stock is now available and it’s perfect for forming sill pans: pvc bends easily and forms crisp joints. End caps can be fabricated and attached with pvc cement, creating a water-tight bond. And pvc doesn’t degrade when exposed to UV rays, like self-adhesive polyethylene membranes do, so the pan can also act as a permanent trim strip beneath the threshold, covering any gap between the bottom of the threshold and the subfloor. Unlike metal pans, pvc won’t react to concrete, aluminum, pressure-treated lumber or moisture. Install the pan on top of a cant strip, then place shims on the pan before installing the window or door unit.

Cut the housewrap properly

Installing Doors

The biggest mistake most installers make is cutting an X through a window or door opening, then folding the housewrap under the header and inside the house. There’s no better way to direct moisture right into the door or window opening. Avoid that problem by cutting a smile at the top of every exterior wall opening. Start with a straight line cut directly under the header, then make a 45º angle-cut in each corner. Next, for doors, cut straight down the middle of the opening, then fold the loose ends inside around the trimmers or jack-studs and staple them inside the wall.

Be sure to wrap the housewrap on the sides over any legs on the sill pan. Before installing the door unit, fold the flap of housewrap at the header up and out of the way. Next, run a bead of polyurethane caulking on the housewrap, at the edge of the opening. Don’t use too much caulking! Squeeze-out could interfere with the adhesion of the flashing tape. Place the new threshold on the shims and tip the frame into the rough opening, pressing it tightly against the wet caulking.

Installing Windows

Windows differ from doors because they have raised sills. Rather than making a straight plumb-cut through the housewrap, make an inverted Y-cut, leaving a loose flap at the bottom of the opening that can be folded in over the rough sill. Install a sill pan in every window opening, too.

Self-adhesive flashing

Sill pans with Flex wrap

Several companies manufacture straight and flexible flashing tapes. Straight flashing is less expensive and should be used for all straight runs. Flexible flashing is ideal for flashing arched windows and sill pans. Begin by running a band of straight flashing beneath the rough sill, then install a piece of flexible flashing on the sill itself. Stick the flexible membrane to the sill and allow it to hang in the air over the straight flashing. Start flexing the flashing by pressing your fingers into each corner and pushing the membrane down onto the straight flashing and back against the housewrap. Use a J-roller to ensure a good bond with the housewrap. Some flashing must also be tacked temporarily so that the membrane has an opportunity to bind completely to the housewrap.

Self-healing window and door flashing

Years ago, when we flashed windows and doors with craft paper; we relied on caulking to adhere the paper to the nail fins and brick mold. But because of rapid changes in building technology, it’s more important than ever to protect wall cavities from moisture penetration. And caulking is a temporary solution. The only certain way to accomplish a long-lasting waterproof opening is to install a sill pan in every opening, and use top-grade self-adhesive and self-healing flashings around every door and window, the final step in creating a leak-proof opening. Apply vertical flashing on both sides of the window or door, running the flashing tape up to the header flap in the housewrap. Then run one last piece of flashing horizontally across the top of the window or door, being sure to extend that piece past the angled cuts in the housewrap. Now you can pull the flap of housewrap down over the head flashing, and tape over the angled cuts. Run a few pieces of tape on the bottom of the head flap, so the wind won’t catch it, but don’t tape it off completely. Any moisture that gets behind the housewrap above the window needs an avenue of escape.

Head flashing

Head flashings should be installed above every door and window, especially above the exterior trim. But that’s another story for another day. In my next article, I’ll discuss head flashings along with other ways to protect exterior trim and increase the longevity of siding, trim and paint. Some lumberyard staff members might wonder why LBM Journal publishes installation articles. Here’s why: Installation issues are important to builders and homeowners today, and will become even more important as building values—the investment we have in our homes—increase. Pursuing professionalism and craftsmanship will always position your company for the future and create long-lasting relationships with your customers. Craftsmanship begins with education. Educate your sales force so that they’re more than sales people. Support their long-term career needs by helping them become building products professionals, so that the next time a customer asks questions about who, what, and why—whether the customer is a builder or is the builder’s homeowner—your sales people will know the right answers. That’s craftsmanship. And it sure beats low prices.  Learning centers are one of the best ways to ensure that your in-house installers and your contractor customers stay technically proficient. The training they receive not only builds their expertise, it also helps protect their reputation and yours. If your yard is considering a learning center, think about contacting a manufacturer like Andersen Windows. In addition to dealer-sponsored contractor events featuring industry experts, Andersen offers customer training programs in “best practices” at its company headquarters, or nationwide through its dealer network. It’s a good way to learn from the experts and provide quality education to those who play a role in the success of your business.

SIDEBAR:

Manufactured sill pans

Several companies now offer manufactured pans. If you’re going to use manufactured pans, be sure to plan ahead: measure your openings (width of opening and thickness of wall), and get your order in so that you pans are delivered prior to your windows and doors.

SureSill also offers an innovative sill pan. Shipped in three pieces, along with a small can of pvc cement, the center section is cut to fit the opening. The end caps are locked and glued into the molded pan. The molded pan is sloped across the entire length, ensuring good drainage, with frequent stand-offs placed to support thresholds and window sills. http://www.suresill.com/home.html 

Jamsill Guard ships its pans in three pieces—two end caps (with new innovative sloped drainage), and a center section, which allows the pan to telescope and fit nearly any door opening. On-site cutting and final fitting is easy. www.jamsill.com 

Dow now produces the Weathermate sill pan, a two-piece molded polymer design that’s available in only 3 3/4-in. depths, for 2x4 wall construction.

Dinesol manufactures polypropylene sill pans in a variety of widths (for 2x4 and 2x6 walls), and lengths for every door or window size. http://www.dinesolbp.com/specialty_products.html