How Many Layer Of Roof Shingles

The standard practice was that you could install a new layer of singles directly over the old layer during a re roof.

How many layer of roof shingles.

However this depends upon the roof materials. Any more than that and you d have to tear off the old shingles before installing a new layer. Steep sloped roof products such as tile slate metal and shakes only allow one layer. 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.

For many years it was acceptable to put even the third layer. Chances are your roof structure was designed for a dead load of one layer of shingles plus extra for snow and a safety margin. 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 come in two major types 3 tab and architectural.

Asphalt shingles typically can have one more layer added over the top two roofs total. Roofing layers from the framing to the shingles. 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. Good quality composite shingles can weigh 350 to 450 pounds per square 100 square feet of roofing installed.

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. 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. 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.

Depending on the pitch of your roof and the type of shingles currently being used the number of layers may be restricted. Shingles are the element that most homeowners are familiar with as it is the layer you can see from the outside of your home and it is an important aesthetic aspect. 3 tabs are less expensive but also less durable have lower wind resistance and have a flatter appearance. Framing includes the roof trusses that sit at the top of your house and support the weight of all the materials used to build your roof.

On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing.