How Many Layers Of Shingles Should Be On A Roof

However this depends upon the roof materials.

How many layers of shingles should be on a roof.

Your three layer roof is definitely a potential structural concern and homeowners insurance companies might consider three layers of roof shingles. Underlays have remained intact after shingles have blown away thereby providing temporary roofing 7. That limit pertains to roofs with up to a 4 12 pitch. In the portland area as of 2018 the current code allows up to three layers if the current layer is in good condition.

For example cedar or tile roofs are only allowed one layer. Underlays are quickly applied and they can provide temporary roofing before the roof shingles are installed. 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. Regulations allow a maximum of two layers of shingles on a roof but experts say you shouldn t lay asphalt shingles over an existing roof.

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. Roofing layers from the framing to the shingles. When it s time to replace the roof again and you have no choice but to start anew two layers is the maximum allowed in most areas you ll have to pay extra for the two layer tearoff and disposal. For example there s a starter course of roofing shingles installed at the eaves before the roofing shingles you can see.

A roofing contractors 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. Most building codes allow up to two layers of organic or fiberglass asphalt shingles. For many years it was acceptable to put even the third layer. On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing.

So we ll start at the bottom of the deck and work our way up through all the roofing layers until we reach the shingles and sunshine above your roof.