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.

How many layers of shingles should be on a roof.

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. 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. 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. Roofing layers from the framing to the shingles.

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 example cedar or tile roofs are only allowed one layer. 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. Eliminating the tearoff can easily save 1 000 or more on a new roof but you re really just delaying the cost. 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. For many years it was acceptable to put even the third layer.

In the portland area as of 2018 the current code allows up to three layers if the current layer is in good condition. Asphalt shingles typically can have one more layer added over the top two roofs total. On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing. Underlays are quickly applied and they can provide temporary roofing before the roof shingles are installed.

Resins from green lumber roof decks have been known to interact with roof shingles and a separation layer of underlay can be useful.