On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing.
How many layers of roofing are allowed in nyc.
For example cedar or tile roofs are only allowed one layer.
Disadvantages to a roof recover.
To get straight to the point there should be only 2 layers of roofing materials on your roof.
The homeowner will have two layers of shingles protecting the roof and the home is less likely to have ice dams he says.
Two layers is the maximum in most areas but some building codes allow only one.
Homeowners have to also keep in mind that most roofing materials are heavy and can easily weigh over a ton.
However this depends upon the roof materials.
Your three layer roof is definitely a potential structural concern and homeowners insurance companies might consider three layers of roof shingles.
Most building codes allow two layers of organic or fiberglass asphalt shingles on roofs with a 4 12 pitch or less and three layers on steeper roofs.
Richards also estimates that the homeowner saves at least 1 000 in costs associated with removing and properly disposing of the existing shingles.
That limit pertains to roofs with up to a 4 12 pitch.
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.
In the portland area as of 2018 the current code allows up to three layers if the current layer is in good condition.
If the structure can support the added weight a typical 20 square 2 000 square foot reroof will cost at least 1 000 less than a tear off job.
However in almost all areas it is not acceptable to install more than two layers of roofing on any commercial building.
For example towns in climates with heavy hailstorm activity or significant ice dam problems may not allow multiple roofing layers.
For many years it was acceptable to put even the third layer.
Local codes might not allow re roofing.
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.
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.
The soundness of the building you re re roofing is another consideration.
Why would you want to recover vs tear off.
