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Apr 8, 2016
Is adding blown in insulation a good way to eliminate ice damming and what other steps can be taken?
Apr 10, 2016

This time of year, we start receiving panicked emergency calls for leaky roofs that failed during the tough winter season. Most roofs fail long before their anticipated lifespan and not just because of their age.

Main reason? Improper attic insulation or ventilation prevents the continuous airflow of outside air into the attic. When ventilation is done right, there is a continuous airflow up through the soffits continuing through the ridge or mechanical vents. This helps during the warm summer months when attic temperatures can reach well over 130 degrees, as well as during the winter during that horrible “ice dam” building season.

The goal is to balance the airflow and temperature protecting the valuable living areas below. A good rule of thumb is one square foot of attic ventilation for every 300 s.f. of attic space. IE: If your attic is 1200 s.f., you’ll need a total of 4 s.f. of ventilation split equallywith 2 feet in the soffit/eave and 2 feet out the ridge or mechanical vents. This will ensure good airflow through the attic.

We all know of those dreaded ice dams ! Having the right amount of insulation keeps the heat where it should be, in your living area! When you do not have proper insulation, it allows the warm living space air below to rise making the attic warmer. The result is melting snow turns into water, water then runs toward the eave where it re-freezes creating ice dams. Water then builds up under the shingles and you know the rest of the story – wet ceilings, walls- a total mess.

We’ve seen all sorts of problems including mold, mildew growth, plywood deflection, curved shingles, wood rot, frame rot, etc.

Short term, the easiest way to keep your heating/cooling bills down and minimize your likelihood of an ice dam is to have proper insulation and attic ventilation. Long term, you’ll be extending the lifespan of your roof and preventing expensive repairs.

Rob Myers of Myers Homes PRO answered:

Apr 11, 2016

Adding insulationis only one piece of the puzzle. The object is to keep the attic space roughly the same temperature as the ambient outside air. This is accomplished via insulating the building envelope to keep your heat IN the building, AND proper ventilation of the attic space to move air around and through the attic. Adding insulation can help with the former, while making surte tha you have proper ventilation is also key. In many cases, the design of the roof or the environment the home is in isn't conducive to these static techniques and ice will form anyway. In those cases, we've had 100% success with properly installing ice melt systems along those sections of roof and gutter to allow water to work its way down through the gutters and downspouts and not build up behind an ice dam. See in the pic the area with the cables, and to the right the area without (which we've since added!) Good luck!

Jun 21, 2016

As previous answers point to adding proper insulation in the attic, it is also recommended that using a leak barrier under the roof shingles from the eave of the roof back until you reach 24 inches above an interior wall.  In other words, the leak barrier, a rubber like membrane that adheres to the roof deck, will cover the overhang and at least 24 inches above the interior wall of the house around the perimeter.  This membrane helps prevent water from melting ice dams from entering the home and overhang (soffit).  Its rubber like properties help seal around the nails that are driven through it that hold the shingles on.  If your roof does not currently have a leak barrier, the existing shingles will have to be removed and replaced where the leak barrier is to be installed.  A couple of recommended leak barrier products from GAF are WeatherWatch and StormGuard.

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