How Many Layers Of Roof Shingles Are Allowed In California

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.

How many layers of roof shingles are allowed in california.

That s also why building codes commonly limit re roofing to no more than two layers. Most building codes allow up to two layers of organic or fiberglass asphalt shingles. This will also be constrained by other factors. Asphalt shingles typically can have one more layer added over the top two roofs total.

Under title 24 the roofing materials need to be sufficiently rated by the cool roof rating council. For example there s a starter course of roofing shingles installed at the eaves before the roofing shingles you can see. 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. On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing.

In some instances 3 layers may be allowed but this is rare. Generally it is fine to have three layers of shingle but you should check this with your local building permit people and you should make sure that your roof and the rest of the structure have the strength to cope with the extra weight. For many years it was acceptable to put even the third layer. In addition under title 24 wood shake roofing would have to be treated with fire retardant chemicals among many other.

Under title 24 cool roofs are required for commercial buildings where either 50 percent or 2 000 square feet of the existing roof is replaced recovered or recoated whichever is less. Most areas only allow for a maximum of two layers. 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. 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.

That limit pertains to roofs with up to a 4 12 pitch. 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. Steep sloped roof products such as tile slate metal and shakes only allow one layer.