R-values of ceiling and walls
Zone 5a (on the border of zone 4)
Existing uninsulated concrete slab.
No basement. 2×4 frame.
A bunch of newbie questions.
Why is the insulation recommendation for an attic so much higher than for an cathedral ceiling?
Both are the shell of the building but the attic has an ceiling under it that at least adds some insulation value. I would expect the recommendations to be closer or even reversed.
Many sites stress the importance of a high R-value to save energy.
More insulation saves energy; but that seems only part of the equation if I look at the recommended R-values.
The fact that floor and ceiling/attic have higher insulation recommendation than walls shows those area’s leak much more energy.
But when checking calculation on some sites the energy loss is a simple relation between inside temp, outside temp and R-value. If it was that simple I would expect the insulation values the same for the whole house.
Attic R-38 vs wall R15.5 ==> Can I conclude that an attic leaks 2.5 more energy by the same R-value?
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