Recommended Insulation Levels (R-Level) Map

Your geographic location has a lot to do with the amount of insulation your home needs to run efficiently. The chart below offers a look at Houston and surrounding cities which rank very high on the recommended insulation levels (Zones 2 and 3). Being closer to the equator simply means more direct sunlight and increased temperatures. The Insulation Guru must take this fact into consideration when recommending insulation solutions for your home’s specific needs.

Map displaying zonal information for recommended levels of insulation

Zone Add Insulation to Attic Floor
Uninsulated Attic Existing 3-4 inches of insulation
1 R30 to R49 R25 to R30 R13
2 R30 to R60 R25 to R38 R13 to R19
3 R30 to R60 R25 to R38 R19 to R25
4 R38 to R60 R38 R25 to R30
5-8 R49 to R60 R38 to R49 R25 to R30


Wall Insulation: Whenever exterior siding is removed on an

Uninsulated wood-frame wall:

  • Drill holes in the sheathing and blow insulation into the empty wall cavity before installing the new siding, and
  • Zones 3–4: Add R5 insulative wall sheathing beneath the new siding
  • Zones 5–8: Add R5 to R6 insulative wall sheathing beneath the new siding.

Insulated wood-frame wall:

  • For Zones 4 to 8: Add R5 insulative sheathing before installing the new siding.