Working on Long Island, we have to prepare our homes to weather the
occasional nor'easter. This type of storm occurs when a powerful
low-pressure area forms during winter, producing strong
northeasterly winds combined with heavy rainfall or snowfall. (If
you're not familiar with one of these storms, watch the movie The
Perfect Storm.) The rain literally travels parallel to the ground,
propelled by intense winds that invariably drive water into places
one would never expect. So when it comes to installing windows and
doors, I'm not afraid of overkill. I'd rather spend the money and
time up front than hassle with the callback later on.
A recent job of mine illustrates the flashing routine I typically
employ. On this particular project, I had to replace an existing
steel window with a sliding glass door. The home was slightly
inland of a 100-mph wind zone, so it did not require the laminated
glass and seacoast fastening required on beachfront homes. However,
it had its own challenges. Typical of a 1950s "Long Island Split"
(a split-level ranch), the home had a brick-veneer exterior, and
the existing window had been installed before the brick, making
Remodeling contractor Mike Sloggatt depends on self-adhesive
flashing to create a drainable flashing assembly. He has never had
a callback using this method.
I wanted to avoid removing the brick to get at the steel flange, so
we set about removing the glass and the frame first, which would
allow us to pry the flange loose. I've dealt with many windows just
like this, so I knew there was no polite way to go about the task.
The fastest way by far would be to break away the glass and then
cut the steel frame into sections. To contain the glass and avoid
the dangerous mess of shattered glass, I used Protective Products'
Carpet Protection (http://www.protectiveproducts.com), a thin
polyethylene film with an adhesive backing, made to protect carpet
during construction. The film also sticks well to glass. By
applying it to both sides of the glass, we were able to break the
window out of the frame without having it fly all around the job
site (Figure 1).
Once the glass was removed, a reciprocating saw made quick work of
the frame. To extract the frame from behind the brick, we slipped a
6-inch metal-cutting blade behind the flange and cut through the
nails. This allowed us to pry the frame out from behind the brick
using a fireman's 36-inch halligan bar.
The client selected a Marvin Integrity slider — one of the
few 9-foot factory-constructed doors that fit our existing opening.
Preparing the opening for the new door simply required removing the
remaining low wall below the window and a few courses of
FIGURE 1. Carpet Protection — a strong,
self-adhesive plastic film — adheres well to glass (top).
When it's applied to both sides of the window, the glass can be
broken out without creating a hazard (bottom).
Outside, we will be installing a deck, so I had to plan the door
installation to work with the future deck design. I have two major
concerns with deck-level door installations: water infiltration and
The usual way of coping with water entry is to try to create a
barrier to keep out the water, never letting it get past the
exterior envelope. That approach rarely works, however. There are
too many pathways for water to find and too many elements —
caulk, siding, and roofing — that can fail. Moreover, any
barrier that keeps water out will also keep water trapped in the
building cavity once it gets there.
Instead, I always use the drainage method. This approach assumes
that water will eventually find its way past the primary line of
defense — the siding and trim — and relies on a
secondary drainage plane that diverts the leaking water down and
away from the opening.
I start establishing my drainage plane from the bottom up. First, I
set a layer of self-adhering flashing tape over the rough framing
and lap it on top of the brick veneer to direct wind-driven rain
away from the void between the sheathing and the brick veneer
(Figure 2). There are a number of peel-and-stick membranes on the
market that can be used for this. We typically use Grace Vycor Plus
— an asphalt-based flashing tape that I have relied on for
many years (http://www.graceathome.com). It's economical, and I
have never had an instance in which the tape has failed. When I
return to install the deck, this first layer of Vycor Plus will be
integrated into a protective layer that will isolate the ledger
board from the house sheathing.
FIGURE 2. Deck-level sliding doors are
susceptible to water and air infiltration. To reduce problems, the
author begins with a layer of self-adhesive flashing beneath the
subfloor and lapped onto the brick veneer.
The next step is to install a copper flashing pan (Figure 3). This
is a positive drainage pan that will prevent any wind-driven water
from pushing into the structure from under the door unit. I bend
the pan on site with a metal brake and solder the corners for
FIGURE 3. The best defense against blowing
rain is a drainable assembly. A drainable sliding door assembly
depends on a copper sill pan (top). The back lip of the pan will be
caulked to the interior hardwood floor and the door's oak saddle
(bottom). This helps seal the air leak that would otherwise create
a strong pressure differential between the indoors and the
outdoors, causing water-laden air to be sucked in.
By bending a 3/4-inch lip on the interior, I can protect the
hardwood flooring from any stray moisture that might be blown in
from underneath or that might migrate from the door sill or frame.
The top of the pan will get caulked against the back of the door
frame prior to installing the oak saddle. This is a very important
seal. Its primary function is to prevent air infiltration. By
sealing this, we are, of course, stopping drafts. But we are also
minimizing the pressure differential between the indoor and the
outdoor air when a storm is blowing. A strong difference in air
pressure can literally suck in water-laden air through the tiniest
cracks. Sealing the opening shuts off the air drive that might
otherwise force water under the door unit. And by leaving the front
of the pan open, any stray water that might find its way to the pan
will drain out and away from the building. This keeps the outside
environment outside, where we want it.
Installing and Flashing the Door
Before installing the door, I wrapped the trimmers with the Vycor
Plus (Figure 4). This flashing strip should lap over the upturned
edge of the copper pan so that any water that might drip down the
flashing will drain into the pan and toward the exterior. It's
important to remember to never reverse-lap, or water can seep into
the interior cavity.
FIGURE 4. The author sandwiches the door's
nailing flange in Vycor Plus (both photos) — one layer
hugging the trimmers and a second layer lapping the flange. While
sometimes considered a redundancy, this "belt and suspenders"
approach provides protection from the hard-driving northeasterly
winds that blow across Long Island in winter.
To install the door, we removed the sliding panel to make the unit
as light as possible. We then lifted the door up onto our
scaffolding. The sill was already dead level, so shimming the
bottom sill was not necessary. (On large door units, I find it
better to reset the sill and get it perfectly level rather than try
to shim the door.) I checked that the door was square in the
opening by using a diagonal measurement across the unit. We
double-checked for plumb and level before installing the sliding
panel, then checked to make sure the door operated smoothly.
This door model called for nailing the flange to the sheathing with
11/2-inch roofing nails and side jamb screws. The side jamb screws
were not a problem; I first shimmed behind each side jamb screw
before setting the factory-supplied screws into the existing
trimmer studs, repeatedly checking the door operation as I went.
But nailing the flange would have been tough because of the brick
veneer. Not willing to risk damage from an errant hammer head, I
instructed my helper to screw it in with 2-inch coated deck screws
instead of using the roofing nails. Most manufacturers require a
bead of caulk on the back of the nailing flange as well. While this
barrier by itself is unlikely to keep out water over time, it's
always wise to comply with the manufacturer's instructions. This
will cover you in the event of a problem later.
Next, I installed another strip of Vycor Plus flashing to prevent
driving rain from getting into the cavity between the rough framing
and the door unit. To make this piece, I stripped smaller widths
out of the standard 9-inch width. To facilitate slicing the
flashing tape, I use a scrap strip of plywood into which I've cut
saw kerfs at 3, 4, 5, and 6 inches from one edge. I can then lay
the tape over the board and easily run a utility knife down the
It's a good idea to wipe down the door frame with alcohol to clean
the flange before applying the flashing tape. When installing the
flashing, I cover about 1/4 inch of the flange — enough to
cover the mechanical joint but not so much that it can be seen
after the exterior trim is installed.
This particular home had a large soffit overhang, which is a good
design for this climate. First, it protects the windows and doors
from a lot of the rainwater. Second, there is less heat absorbed
through the glass panels in the dead of summer when the sun is
high. The winter sun, however, is low enough to shine under this
overhang so it can warm the room during the day.
Even with such an overhang protecting the opening from water, we
still take care to seal the top flange (Figure 5). The lesson I've
learned is that, invariably, someone will decide to power-wash the
soffit, siding, and door. By carefully sealing above the door and
pushing the flashing membrane up into the soffit area, I know it
won't leak even with water sprayed into the joint at 3,500
FIGURE 5. Even though a deep overhang protects
the head jamb of this opening, the author takes care to seal the
head as well (above). He's learned from experience that unless this
is done, someone will inevitably power-wash the exterior and
inadvertently create a leak.
Though it's not shown in the photos, the final exterior treatment
will be a wood trim, such as WindsorOne preprimed 5/4 trim stock
(http://www.windsorone.com). In more severe exposures,
I would use Azek cellular PVC (http://www.azek.com). We will caulk the
exterior face against the brick with a high-quality polyurethane
caulk but will leave the bottom joint open for drainage.
Some builders feel the multiple layers of Vycor are overkill for
door flashing, particularly for such a protected opening as this
house design affords. But I have never had a callback on a door
we've installed using this method. I have, however, repaired many
doors that I did not install. In one case — a waterfront home
on the north shore of Long Island — water infiltration
damaged the hardwood flooring, the wallboard, and the door slab.
Four attempts to stop the water had been made by the home builder
before the homeowner asked us to remedy the problem. Using the
method I've described here, we removed and reinstalled the door,
properly layering the weather barrier and removing the caulking the
builder had applied in an attempt to stop the water. On that job, I
confidently told a very skeptical client to pay me after the next
nor'easter. I received my check three months later. ~Mike Sloggatt has been remodeling old homes on
Long Island for more than 27 years and is a member of the JLC Live
construction demonstration team. All photos by the author and his