How Many Layers Roof Has Shingles

For example cedar or tile roofs are only allowed one layer.

How many layers roof has shingles.

However this depends upon the roof materials. For example there s a starter course of roofing shingles installed at the eaves before the roofing shingles you can see. In the portland area as of 2018 the current code allows up to three layers if the current layer is in good condition. The average 30 square roof uses 90 bundles of shingles and a bundle of asphalt roofing shingles weighs about 100 pounds which means you re putting roughly 9 000 additional pounds of weight on your roof.

Good quality composite shingles can weigh 350 to 450 pounds per square 100 square feet of roofing installed. Most cities and towns allow a maximum of two layers of shingles says chad muth president of muth company roofing in westerville ohio. 3 tabs are less expensive but also less durable have lower wind resistance and have a flatter appearance. Chances are your roof structure was designed for a dead load of one layer of shingles plus extra for snow and a safety margin.

For many years it was acceptable to put even the third layer. Asphalt shingles come in two major types 3 tab and architectural. There are multiple layers of materials and they have to be installed in the right sequence and the right way in order to withstand harsh weather and keep your home dry. Asphalt shingles typically can have one more layer added over the top two roofs total.

That limit pertains to roofs with up to a 4 12 pitch. A roofing contractor will know exactly how many layers of roof shingles are allowed in your area for your building but it is normal that you will be permitted up to three layers of shingles. 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. On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing.

Most building codes allow up to two layers of organic or fiberglass asphalt shingles. But contractors who spoke with angie s list say best practices call for stripping the roof down to the wood deck to inspect it before installing a new roof. Your three layer roof is definitely a potential structural concern and homeowners insurance companies might consider three layers of roof shingles.