How Many Layers Of Roof Shingles Are Allowed In Montana

However this depends upon the roof materials.

How many layers of roof shingles are allowed in montana.

One of the largest benefits associated with double layering as opposed to stripping and laying a complete new set of shingles is simply saving costs. On top of the 19 inch strip of underlayment felt. In the portland area as of 2018 the current code allows up to three layers if the current layer is in good condition. For fiberglass asphalt and organic shingles and a pitch under 4 12 as long as the roof structure remains sound you should be able to have two layers of shingles.

The soundness of the building you re re roofing is another consideration. For example cedar or tile roofs are only allowed one layer. That limit pertains to roofs with up to a 4 12 pitch. Adding a second or third layer of shingles adds significant weight to the structure.

Steep sloped roof products such as tile slate metal and shakes only allow one layer. 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. On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing. Roofs between 2 12 to 4 12 pitch can use standard asphalt shingles but must have two layers of underlayment installed in the following manner.

Most building codes allow up to two layers of organic or fiberglass asphalt shingles. 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. 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.