A two-layer shingle roof can be a great idea if your house was built recently enough for the shingles to still be good quality. A two-layer roof sheds snow and ice better and also reduces leaks that are caused by ice dams. If your house was built a while ago, you’re running the risk of having a less sturdy roof due to the age of the shingles. For example, if your roof was installed more than twenty years ago, it is likely your shingles were made from synthetic fiber and are a high fire hazard. Terms to look out for when inspecting your roof are “flakes” and “fog”. Flakes are water vapour deposits on the surface of your roof tiles or on their surface. Fog is the usual description for damp patches on ceilings during the colder months of the year. Both can be a sign that your roof isn’t in the best condition and needs attention.
Shingles are often considered as a quick solution for roofing problems, but they can actually cause problems of their own. Installing shingles on top of your roof can put a greater strain on the roof and lead to premature wear, leaks, mold, and eventually even collapse. It is important to keep in mind that shingles are not meant to be an extended solution for roofing problems, but only a short term fix. When installing new shingles, it is also important to make sure the first layer of shingles are installed properly and that the second layer is installed with a slight gap around the edges to allow for air flow, which can help prevent moisture accumulation and mold build-up.
In the past, homeowners had a hard time with choosing the right roofing shingles. First, there is the problem of two layers of shingles. A plywood underlayment layer is needed to give enough room for the thicker shingles. The biggest issue with this is the number of nails needed and the potential for leakage. As a homeowner, you have to determine whether you need a price roof or a plywood underlayment layer. If you choose plywood underlayment, it will take twice as many nails and there is the risk of a roof leak. If you choose a price roof, it will not be as durable but may have a lower risk of roof leak.