Quote Originally Posted by dan sw fl View Post
I understand ACH=
_____TIGHT __: 0.15
SEMI-TIGHT __: 0.26
_ AVERAGE __: 0.39
SEMI-Loose __: 0.61
___ Loose ___: 0.82

based on my use of Manual J8 abridged.

Some residences with foam products ought to be < ~0.2
Right Dan; I was just using .4 ACH for his situation because his home needs to be above the code minimum home air-changes of 0.35 ACH, when it is properly ventilated.

Of course, the proper way is to do the blower door test & use the actual lower ACH number so the load-calc would estimate the needed makeup air...then he should use 0.2 or less ACH.