How much insulation a house needs in IECC climate zone 4 — attic, walls, and floor
A house needs the most insulation overhead: in climate zone 4 the IECC requires R-60 in the attic, R-30 in the walls, and R-19 in the floor. The thicker the layer, the higher the R-value.
What this diagram shows
A house cross-section showing where insulation goes and how much each part needs in IECC climate zone 4: the attic or ceiling needs R-60 (a thick blown-in layer), the exterior walls need R-30 (batt in the stud cavity), and the floor needs R-19 (batt between the joists). The attic layer is drawn thickest because it requires the highest R-value. Values are the 2021 IECC prescriptive minimums from Table R402.1.3.
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