Spray the wall yourself

Five bays of open 2×6 framing, an outlet box and a water line in the way. Pick your foam, fill the cavity, then shave it flush with the studs. The R‑value updates as you go.

Try it yourself

Spray this wall

Five bays of open 2×6 wall. Fill them, shave them flush, and see what R‑value you actually built.

Why the thin spots matter

Heat takes every path at once, so a bay that is half filled drags the whole wall down. The score uses the same parallel-path average a building scientist would.

Why the waste counter matters

Foam that rises past the studs gets shaved off and thrown away. You still paid for it. That is the number that separates a clean job from an expensive one.

Why R-20

MN energy code calls for about R-21 in 2x6 walls (or R-13 cavity + R-5 continuous).

Price your real walls