According to the international existing building code homes can be re roofed one time by applying a second layer of roof shingles over the existing one but after that application begins to wear both layers need to be removed before a brand new roof is installed.

Three layers of shingles on roof. Maybe 5 10 years but the life expectancy of second layer is less than it could be 10 30 years. If you counted it that way you are going to have 3 layers instead of 2 because the first row of shingles at the roof edge is doubled. The homeowner will have two layers of shingles protecting the roof and the home is less likely to have ice dams he says. So it may only be 2 layers of roofing.

How many layers of shingles are allowed on a roof. Also what the individual said about are you counting the layers at the roofs edge he had a good point. Having multiple layers of shingles is going to make your roof hotter because the heat gets trapped between the layers which could mean premature aging of the shingles. The third layer is a waste only lasts a few years maybe.

Benefits of adding multiple shingle layers. This will also be constrained by other factors. In some instances 3 layers may be allowed but this is rare. Most building codes allow up to two layers of organic or fiberglass asphalt shingles.

Architectural shingles make up most roof replacements today as their cost is only marginally more than 3 tab and they come with far superior specifications and warranties. 3 layers of shingles may be too much weight for your roof structure i 39 d be concerned about the roof collapsing. Each layer of shingles puts weight on your roof structure. I 39 d really worry come winter.

Asphalt shingles come in two major types 3 tab and architectural. That limit pertains to roofs with up to a 4 12 pitch. When it s time to replace your roof there are several factors that might lead your roofing professional to recommend adding shingles on top of your existing layers. The contractor may do a walk on the roof and also inspect from the attic for any rot before installing a second layer of shingles.

3 tabs are less expensive but also less durable have lower wind resistance and have a flatter appearance. This structure must support this weight and the weight of other things snow and ice come to mind. Your three layer roof is definitely a potential structural concern and homeowners insurance companies might consider three layers of roof shingles. Adding an extra layer of shingles when the first layer has met it s life expectancy can buy a few more years.

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