For Houses located in Snow Zone areas special precautions should be taken to reduce the possibility of roofing failure and water damage do to Ice Dams.
Ice Dams occur when snow located on a roof melts and then turns back to ice as it enters the gutter system. Once the gutter is filled the ice will start to push up and get under the first layer of shingles along the edge of the roof.
Although it is difficult to totally eliminate the formation of ice in your gutters there are steps you can take to prevent and reduce the effects of ice dams.
When houses are shingled the roofers should always install a ice and water membrane. The membrane will not prevent ice in the gutters but it will provide protection from water entering the house.
Ice and water membrane (shown in red) is a rubberized asphalt material that comes in a 3 foot width rolls and is applied to the bottom edges of the roof. In areas with harsh winters two layers of this material can be applied for about a 5 foot protection with a 1 foot overlap. Membrane can also be used in valleys of the roof and other areas to prevent water damage from icing.
Once you have installed the Ice and Water Membrane and have limited the possibility of water entering the home you will still need to reduce the formation of ice.
Wider Gutters and Downspouts or adding additional downspouts may be necessary. Seamless aluminum gutters in 5″ widths are probably your best bet but they are the most expensive since a contractor must be hired to make the gutter. Seamed gutters are fine but remember to use pop rivets and gutter sealant at connections.
Although Ice will always melt from direct sunlight your attic must be ventilated properly so that heat from within your house will not cause snow to melt. Vents should be installed under your eaves or roof overhangs and additionally at a higher point like the peak of the roof or gable wall. Natural convection will cause the hot air to exit the attic and cooler air to be pulled in from below.
If you have an unheated attic your insulation should be on the floor of the attic space. The minimum amount of insulation is set by code for new buildings but for comfort and reduced energy costs you should always consider adding more insulation up to about R60. Special precautions and materials are necessary so not to pack insulation around eave vents or light cans that pass through the drywall into the attic.
All of your vents for bathrooms or clothes dryers should directly exit the attic space and not vent into the attic area. Metal flexible duct can be secured to exhaust flanges and run to a vent on your gable end of your roof. I would not suggest that you vent vertically through the roof as that will be less water resistant then venting to an exterior wall of the attic.
If you have heating ductwork in the attic you will want to seal it air tight with duct tape and cover it with about a foot of insulation or an R40 to R60.
This is necessary is necessary to reduce heat transfer into the attic and to also improve the heating and cooling of the rooms being serviced.
If you have any plumbing other then vent pipes that pass through an unheated area they should be protected and when possible they should be moved within the heated area of the house.
Dealing with Ice problems
First check for blockage of your downspouts. If you have an extension on the bottom you may need to remove it temporarily if it is filled with ice. Bring it into a warm garage and let it stand in a bucket to melt.
Heavy snows will cause extreme icing. If you have more then a foot of snow on your roof you may need to remove some of it to allow the rest to melt normally. You must be very careful when attempting to remove the snow or you could damage the shingles. To remove snow you can use a ridged metal rake (not a leaf rake) duct taped to a 10 foot pruning or painting extension rod. Never point the teeth of the rake towards the shingles. Using the back of the rake you should be able to remove about 1/2 to 2/3rds of the snow. Don’t worry about removing all of the snow as you may go too deep and damage the shingles.
Once you get the snow off the roof you will want to shovel it away from the house to prevent melting and water entering your basement. In extreme situations you may want to leave an attic door or entrance open and allow the attic to heat and melt the snow and ice. This is probably a last resort but can be used in an emergency to reduce snow load.
As always be careful especially around ice and ladders. If you don’t feel you can safely do the work yourself hire someone.