During the winter months, the temperature in many parts of the country can reach below freezing point and this can sometimes cause issues with some roofs. The most common issue is when ice dams are formed at the eaves due to repeated thawing and freezing. When ice dams build up, pools of water usually collects behind them. However, there are things you can do in order to prevent the water from penetrating the roof deck.
In order to protect your asphalt shingle roof from ice dams, start by installing underlayment to the sheathing and cover the area by the eaves with surface roll roofing. Reinforce the eaves to about 12 inches on the inside of the exterior wall line of the building. I would either use a 36 inches wide 90 pound mineral surface sheet or at a minimum – a 50 pound surface roll roofing in a smooth finish. Allow for a bit of an overhang along the eaves and nail down the roll roofing at even intervals from both the upper and bottom edge and also allow for an overlap at all vertical joints. Then nail down the lower lap to the roof and cement both ends together.
To protect wood shingles and shakes roofs, I would use a 15 pound double layer felt along the eaves or possibly a single layer of a 30 pound felt. Overlap the felt at every 18 inches or so and this includes overlapping at vertical joints but only by 4 inches here. Then cement the layers together.
In order to protect tile roofs from cold weathers, use a minimum of a 40 pound single layer felt. A heavier coated felt would be great but is not a must. Extend the felt from the eave to about 24 inches on the inside of the exterior wall line of the building and use a lighter, say 15 pound felt at the ridge.
De-Icing Tapes and Snow Guards
There are other methods in order to keep your roof ice free and safe. You can purchase electrically heater cables or so called de-icing tapes that can be installed along the roof. This will allow for proper drainage by melting snow and ice. They are insulated and normally installed in a zigzag pattern along the shingles and connected to a waterproof outlet. By installing snow guards in staggered rows to your roof, you can prevent snow from sliding off the roof in big chunks. Glacier-like chunks of snow like this can not only cause injury to people on the ground by it can also rip away roofing material and tear gutters from their fastenings.