Insulation .... Again

Brad White_43

We post on our drawing cover sheet the output of a ComCheck energy calculation. We also send, in letter form, the same information expanded to explain all of the design assumptions (R-values, glass factors for solar gains, shading and heat losses, all surfaces.)

This in essence freezes the design assumptions, right, wrong or indifferent, for all to see.

It is then incumbent upon the architects (for whom we principally work on most projects) to police the practices and their own designs. Too often a glass substitution would be made during construction and without our knowleges as one example. Wall insulation is less volatile but is still subject to revision.

As for quality of installation, our Mass. Energy Code at least requires the Architect to supervise essentially the practices and final installation before concealment. Impractical in real life IMHO, for they cannot be everywhere at once.

The notion that fiberglass passes air is not new, but should not write off the material. It just has to be encased in a good air barrier comprised of other materials. Tyvek over plywood with taped joints is a fairly airtight assembly. With interior drywall gasketed ("airtight drywall approach") you have that covered too. Then the only issue is the internal convection within the fiberglass, less so through-flow through the wall itself. It is not inherently an air stopper and that is where the foams and dense-pack cellulose shine.

My $0.02.

Brad

Ragu

Do you specify?

That building insulation posting of last week was extremely interesting, and leads me to ask how do you other heating contractors proactively protect yourselves from the possibility that the builders won't do an adequate job re: insulating the building envelope?

We are in coastal Maine and the standard insulation is still fiberglass. I have had zero success in convincing builders to upgrade their level of insulation and really take a look at infiltration issues. What I have done is downgrade the R values of fiberglass on my heat losses and increase the ACH.

Have many of you folks actually taken on the role of insulation specifier?