Ice Dams
By
Frank G. Ross
While it may be true
that the groundhog didn’t see his shadow and we are expecting an
early spring, some areas in southern Utah are still experiencing
winter conditions. Snow, warm daytime temperatures and freezing
nighttime temperatures can create ice build-up in a home’s gutters
or over the eaves, generating a condition called an ice dam.
The main cause of ice dams is heat in the attic. Briefly,
ice dams form when snow accumulates on the roof. A warm attic
causes the snow to melt and run down the roof toward the eaves and
gutters. When the melted snow reaches the unheated sections of the
roof (eaves and gutters) it refreezes into ice. As freezing
temperatures continue, the ice builds up. When it reaches a
sufficient height that the melted snow can no longer run off the
roof, water may become trapped behind the ice. This is when an ice
dam becomes a problem.
The roof covering is
designed to shed water toward the eaves and gutters. Shingles,
tiles, shakes, etc. are designed for water to run in a downward
direction. When an ice dam prevents water from running off the
roof, the pool that is formed may actually find its way under the
shingles or tiles to a place where water is not supposed to be.
Once under the roof covering, the water may penetrate the wall or
ceiling structure causing further problems.
As recently as last
week I encountered this problem in both houses I inspected that
day. One home, completed a few weeks previous to the inspection,
had an ice dam in a corner where the garage roof met the main
house. No one was living in the home at the time which may have
been the reason this problem was allowed to continue and create
serious damage. As explained above, water pooled behind the ice
dam, found its way under the roof shingles and leaked into the wall
structure. There was so much moisture in the wall that the portion
of the concrete foundation supporting the wall was visibly wet. The
interior wall surface of unfinished sheetrock was also moist and had
deteriorated to the point that the sheetrock, rather than being
solid like a wall, had a texture more like a slice of white bread.
I can only imagine what the insulation inside the wall looked like.
Ice dams, if allowed to
continue unchecked, can lead to the need for expensive repairs. A
temporary solution is better than none. The problem is that the
water has no way to leave the roof. The solution is to make a way
for the water to drain. A sharp tool can be used to chip a break in
the ice where the water can run out, but there is a chance that the
roof or gutters may be damaged in the process. A safer way is to
use some sort of ice melt product. Fill the leg of a discarded pair
of panty hose with the ice melter. Lay the hose onto the roof so it
crosses the ice dam and overhangs the gutter. The ice melt will
eventually melt through the snow and ice and create a channel for
water to flow down into the gutters or off the roof.
Since excessive heat in
the attic triggers the process that creates ice dams, the best
defense is to keep the attic cool with good ventilation and adequate
insulation. A rule of thumb for attic insulation is about R-38
(about 15”). Also, be sure to close all air leaks into the attic,
and insulate and seal all access doors. A general guideline for
ventilation is about one square foot of ventilation per 150 square
feet of attic floor space. Resolving heat loss can be tricky with
complicated roof designs, so you may need the help of a professional
to completely remedy the problem.
Once the heat is kept
out of the attic and in the home where it belongs, you can stop
worrying about recurring ice dams when the snow begins to fly and
start planning your winter escape instead.
Frank Ross is a Certified Utah Home Inspector for Pillar to Post
Professional Home Inspection and a full member of the National
Association of Certified Home Inspectors and a member in good
standing with the Utah Better Business Bureau. Readers may contact
Mr. Ross at (435) 867-6400 or
frank.ross@pillartopost.com
