Roofers say R values need to be adjusted for where products will be used

  • The National Roofing Contractors Association argues that long-term thermal resistance calculated in a laboratory for polyisocyanurate and polyurethane foams is not the same as the real-world value.
  • Test R values can meet code, but they it does not take into account thermal resistance loss when metal fasteners are employed, according to a study.
  • Designers also should adjust R values based on the climate where the insulation will be used, the organization recommends.

From the article

To minimize the loss of thermal resistance in design, the R-value of roof insulation should be computed based on the actual performance of the insulation material and the local climate, says the National Roofing Contractors Association. ...

Read more at Professional Builder

Top Image Credit: Bill Bradley