What is the best way to insulate a new roof from the exterior?

Question

What is the best way to insulate a new roof from the exterior?

Asked by Melanie Skelton

I am planning on turning an open attic space into a masters suite. the ceiling will stay open to the trusts. Tin is the option for the roof, so what is available for insulation between the existing roof and the tin.

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Answers

Danny Kelly's picture

The best way (and really the only way) to insulate the exterior of the roof is to install rigid foam on the top of the existing roof decking.

  • Check what your local code minimum R-Value is and determine the foam thickness based from that.
  • For a high performance home, it is recommended to increase the foam thickness to exceed the code minimum.

Your builder or green rater can help you with this decision. A simple cost analysis can be run on different thicknesses and calculate a payback on each option.

For more information:

Read our tips "Three Ways to Make Your Roof More Energy Efficient."