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Layers of Roofing, How many are allowed on my roof?

I've been asked, "Can we install another layer of roofing over the existing?"

The answer varies with every building and project.

It is advised that you seek out the local building department for theexact amount of layers that are acceptable in your area. Every city and county vary with their own codes.

Steep sloped roof products such as tile, slate, metal and shakes only allow one layer. 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.

On most flat roofs such as EPDM, TPO, or modified it is perfectly acceptable to two layers of roofing. However, in almost all areas it is not acceptable to install more than two layers of roofing on any commercial building.

Why would you want to recover vs tear off?

It's all about the money. Recovering a roof can save money in many aspects of the job. First, you can save on dumpster and haul off of tear off debris. Second, you save money on labor hours that it would take to tear off the original roof or roofs. Finally, you can save money on insulation (mostly only applies to flat roof systems). Not having to replace the existing insulation could be the biggest money saver.

Tearing off the old roofs does have many advantages as well. The weight of the roof is of concern, roof trusses and decks are only able to hold up so many layers of roofing. Adding more weight than your roof is designed for can cause structural damage to the building and cause a dangerous situation for anyone in it. Another great perk of tearing off is that it exposing the roof deck. The roof deck can then be inspected for dry rot and easily be repaired if needed.

What should you do?

Every building and every roof is different. The best option for your building could depend on the following factors:

1) current roofing system?

2) how many layer of roofing are existing?

3) what city/county do you live in? and what are the codes?

4) is it a commercial or residential building?

5) what shape is the current roof in?

Real Roof Contracting provides free roof assessments, we would be more than happy to prepare a roof report for you that includes what options are best for your property. Contact us at 314-885-4858 or by email at to schedule an inspection and receive your roof report.

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