Many
cases of “Siding Leaks” are not as they may
seem. Many times interior moisture migrates through the
wall and at the dew point condensation occurs. This cooling
of warm air will always result in the dropping of moisture.
As your breath fogs on the cold windshield of an automobile
in the winter, this condensing of air compresses the molecules
closer together, squeezing the air like a sponge.
The newer
homes have efficient windows and doors, very well insulated
walls, but where the air is allowed to migrate toward the
colder exterior, condensation will occur. This happens in
the bathroom after a shower and on the kitchen walls while
cooking. It is the allowance of moisture laden air to travel
within a warm space toward the colder exterior, in the winter,
which causes the major problems. Remember when you first
get into that cold automobile, your breath just fogs and
drops. It is only after the car begins to heat up that your
breath travels to the windshield to drop its moisture.
Inside the
walls and usually near windows and wherever there are areas
that air can travel, moisture goes with it. The interior
pressures of most residential dwellings are tremendous in
the winter months. The warm air pushes right through walls
to that point where the cold meets the warmth and moisture
condenses.
When the
resulting problems show themselves, homeowners are all too
often sold a “tighter job” with house wraps
and weather barriers, etc. behind their new siding jobs.
Little do they realize that the cycle is about to return
with a vengeance, because their problems have been accentuated
by the new and tighter barrier on the outside of their homes.
These barriers
and house-wraps are sold as “breathable” and
water vapor is supposed to be able to pass through. The
problem occurs when the cold temperatures condense the air
and moisture becomes trapped behind the barrier. Take a
look at what most people would call a siding leak in the
photograph below. The moisture came from within the wall!
The site conditions along with the barrier caused the condensation!
House-wraps are not breathable in the winter! If you do
not believe it, try the following:
Boil a pot
of water in the winter.
Open a window with a screen closed.
Carefully set the pot on the window sill and support it
so as not to spill.
Watch the moisture migrate to the outside in the form of
vapor.
On the screen, which is a thousand times more “breathable”
than any House-wrap, water will be streaming on the inside
as the warm air that is holding the vapor condenses.
Solution:
1. Do not look to house wraps as a solution to your “Siding
Leaks.”
2. Have
the moisture content of the interior of your home tested.
40% is considered normal.
3. Check
for wet basement problems. Find out if your crawlspace or
basement has a vapor barrier.
The doormat
test is a good one. By the book, a 12" x 12" piece
of plastic is taped to the floor of the crawlspace or basement
for a day or two and when removed, if moisture can be observed,
your slab or floor does not have a proper vapor barrier.
A doormat works just fine and it is a little bigger. Skip
the tape.
4. Check
your heating system for overactive humidifier.
5. Pull
the interior trim on the windows of your home and insulate
window frames and tape off gaps at rough openings. Paint
interior with enamel paint that forms vapor barrier.
6. In the
Northeastern climate, Vapor Barriers should be installed
on the inside, warm side of the wall, where water vapor
remains airborne and in a gas state in the winter months.
Although conditions are many times reversed in the summer
months, the pressures from the outside never rival those
from within during the winter months.
7. Take
heed and make sure you are not spending your home improvement
dollars on measures that will make your problems worse.
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