A blower-door test on an older home I’m renovating shows a need for some serious air-sealing. Unfortunately, a previous owner blew about a foot of loose cellulose into the attic without first addressing any of the usual sources of air leaks. Rather than shoveling cellulose out of the way and patching the leaks we can find — possibly missing some problem areas — I’m thinking of having an insulation sub vacuum up all the existing material, then seal the area with a flash layer of closed-cell foam. If we go that route, is there some way to re-use the original cellulose, or would that be more trouble than it’s worth?

A.Jonathan Tauer, an insulation contractor in Florence, Mass., responds: There’s no problem with vacuuming up and reusing existing cellulose, as long as it’s not mixed with lumber scraps, old plaster, or other debris. Insulation suppliers can provide vacuum bags large enough to hold several cubic yards of loose cellulose. The easiest way to fill...

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