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Your Roofing Questions Answered

How Much Ventilation Do I Need?

Proper attic/roofspace ventilation will help with energy efficiency, help reduce ice damming, and also help prolong the life of your roof. The amount of ventilation needed is easy to figure. Industry standard is that for every 300 square feet of attic space, you need one square foot of intake ventilation and one square foot of exhaust ventilation. An even better way to do it is to run continuous soffit ventilation (intake) and continuous ridge ventilation (exhaust).

What Causes Icicles Along The Eaves And What Can Be Done About It?

The problem is a common one called "Ice Damming". Ice dams form when snow continually melts at the roof edge. When snow accumulates on a roof, the heat in the attic will cause it to thaw and the resulting water will run down to the eaves where there is no heat and it will refreeze. This can occur on a daily basis until large icicle form at the eaves. If no protection was installed when the roof was put on, the ice can eventually back up under the shingles and cause leaks. It can also get bad enough to rip the gutters right off of the building. Ice dams can allow moisture to damage attic insulation which reduces the R-value of the insulation and raises the energy bills, they allow water to penetrate wall cavities which can cause paint and plaster to peel and also rust nails, electrical boxes, or any other non-rustproof metal building material located in walls. There are three good ways to help prevent ice dams or the damage caused by ice dams. Proper ventilation will help maintain the ambient air temperature at the roof level thereby not allowing the snow located on the roof above the living areas of the home to thaw. Heavy attic insulation will help insure that very little heat gets into the attic. The installation of an ice and water protection membrane to the eaves and valleys of the roof which will help prevent damage, but doesn't treat the root of the problem, which is heat loss. Heat tapes are often used as a solution but rarely prove effective.

How Do I Roof Over A Hole Made From A Skylight?

Skylights are a big problem. If you don't know anything about doing patch work to tar & gravel roofs, I strongly advise that you contact a roofing contractor. It's not difficult, but you do need to know something about it. After removing the skylight, you'll want to cover the hole with decking material. Use the same kind of decking that is on the rest of the roof. My guess is it's probably 1/2" CDX plywood (CDX simply means it's rated for exterior use). I have to tell you that all professional roofing organizations recommend that the plywood be replaced in whole sheets only. What I mean is, don't just cut a piece to fit, you need to replace the entire piece. It has to do with maintaining the structural integrity of the roof. Now comes the roofing part. I really can't help you here without actually seeing the project. I can give you some tips, though. (1). Your tie-in with the existing roof should be at least 12" in width. (2). You should prime the existing roof with asphalt primer which available at most hardware stores. (3). You can use Cold Process materials which will make it easier if you do it yourself.