The R number in insulation tells you how well the material resists heat flow: the higher the number, the better the insulation. In simple terms, a higher R-value means less heat escapes in winter and less heat gets in during summer.

What it means

  • R stands for resistance to heat flow.
  • A higher R number means better insulating performance.
  • It depends on the material and its thickness, so thicker insulation usually has a higher R-value.

Easy example

R-13 insulates better than R-7, because it resists heat moving through it more strongly.

Why it matters

Choosing the right R-value can help keep a home more comfortable and reduce heating and cooling demand.

TL;DR: the R number is insulation’s heat-resistance score; bigger is better.