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12.30.26: Help Article
RSC Builders Tips
Preventing Ice Dams
Help! There's An Ice Dam on My Roof. Now What?
Your best strategy is to sit tight
and wait for the ice to melt away. Later you should focus on preventing future dams
by making the improvements described below.
Dam Busters
Stopping ice dams is simple, in principle: Just keep the entire roof the same temperature
as the eaves. You do that by increasing ventilation, adding insulation, and sealing
off every possible air leak that might warm the underside of the roof, as shown in
the illustration below. By taking care of these trouble spots, listed here in order
of priority, you should enjoy a winter free of dams and use less energy to boot.
1.
Ventilate Eaves And Ridge
A ridge vent paired with continuous soffit vents circulates
cold air under the entire roof. Both ridge and soffit vents should have the same
size openings and provide at least 1 square foot of opening for every 300 square
feet of
attic floor. Place baffles at the eaves to maintain a clear path for the airflow from the soffit vents.
2. Cap the Hatch
An unsealed attic hatch or whole-house fan is a massive opening for
heat to escape. Cover them with weather stripped caps made from foil-faced foam board
held together with aluminum tape.
3. Exhaust to the Outside
Make sure that the ducts connected to the kitchen, bathroom,
and dryer vents all lead outdoors through either the roof or walls, but never through
the soffit
4. Add Insulation
More insulation on the attic floor keeps the heat where it belongs.
To find how
Much insulation your attic needs, check with your local building department.
5. Install Sealed Can Lights
Old-style recessed lights give off great plumes of heat
and can't be insulated without creating a fire hazard. Replace them with sealed "IC"
fixtures, which can be covered with insulation.
6. Flash Around Chimneys
Bridge the gap between chimney and house framing with L-shaped
steel flashing held in place with unbroken beads of a fire-stop sealant. Using canned
spray foam or insulation isn't fire safe.
7. Seal and Insulate Ducts
Spread fiber-reinforced mastic on the joints of HVAC ducts
and exhaust ducts. Cover them entirely with R-5 or R-6 foil-faced fiberglass.
8. Caulk Penetrations
Seal around electrical cables and vent pipes with a fire-stop
sealant. Also, look for any spots where light shines up from below or the insulation
is stained black by the dirt from passing air.