The soundness of the building you re re roofing is another consideration.
How many layers of roof shingles are allowed in ohio.
Steep sloped roof products such as tile slate metal and shakes only allow one layer.
Asphalt shingles come in two major types 3 tab and architectural.
In the portland area as of 2018 the current code allows up to three layers if the current layer is in good condition.
For example cedar or tile roofs are only allowed one layer.
Finally consider whether reroofing over the old shingles is even allowed where you live.
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.
For instance ohio code chapter chapter 4101.
The 2006 residential code of ohio rco states in section r905 2 7 1 states that when table r301 2 1 criteria so designates an ice barrier that consists of at least two layers of underlayment cemented together or of a self adhering polymer modified bitumen sheet shall be used in lieu of normal underlayment and extend from the eave s edge to a point at least 24 inches from the inside of the exterior wall line of the building.
But contractors who spoke with angie s list say best practices call for stripping the roof down to the wood deck to inspect it before installing a new roof.
Asphalt shingles typically can have one more layer added over the top two roofs total.
For many years it was acceptable to put even the third layer.
Most building codes allow up to two layers of organic or fiberglass asphalt shingles.
Most cities and towns allow a maximum of two layers of shingles says chad muth president of muth company roofing in westerville ohio.
Adding this membrane isn t an option with a re roof and the extra layer of shingles offers little protection against ice dams.
For closed valleys valleys covered with shingles valley lining of one ply of smooth roll roofing complying with astm d 6380 and at least 36 inches 914 mm wide or types as described in item 1 or 2 above shall be permitted.
In snowy climates most new roofs these days get an ice and water shield a rubbery moisture membrane applied to the sheathing along the eave to protect against ice dams.
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.
The bottom layer shall be 18 inches 457 mm and the top layer a minimum of 36 inches 914 mm wide.
That limit pertains to roofs with up to a 4 12 pitch.
However this depends upon the roof materials.
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.
