How Many Layers Of Roofing Are Allowed In Nyc

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.

How many layers of roofing are allowed in nyc.

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. Asphalt shingles typically can have one more layer added over the top two roofs total. 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.

Steep sloped roof products such as tile slate metal and shakes only allow one layer. Fasteners for asphalt shingles shall be galvanized stainless steel aluminum or copper roofing nails minimum 12 gage 0 105 inches 2 67 mm shank with a minimum 3 8 inch diameter 9 5 mm head of a length to penetrate through the roofing materials and a minimum of 3 4 inch 19 1 mm into the roof sheathing. Any amount of short term savings you might see from a layover roof installation is not far outweighed by the longer term peace of mind that comes from knowing that the integrity of the decking has been confirmed. On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing.