How should cellulose insulation holes be plugged?
A contractor just finished installing cellulose in several walls of my home. I had removed the siding and installed plywood. The installers installed the cellulose by drilling 3 1/2″ holes in the exterior plywood sheathing, blew in the cellulose, then plugged the holes with one part foam. Is this the proper way to plug the holes? I want the plywood sheathing to be an air barrier, and this method of plugging seems weak. Any suggestions of what it should be plugged with, or will the spary foam be durable enough to last?
I am also curious if they installed it dense enough, they used 16 bags of greenfiber for the following;
1) 67′ of 8′ wall = 536 sqft
2) 32′ of 4′ wall = 128 sqft
3) minus 7 windows=70 sqft
For a total of 594 sqft of 2×4 walls.
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I am not one of the pros here, but unless you get other replies, I would bet that the foam will stop air sufficiently for the small area it is. If you think it might work loose, then perhaps stapling/tarring some 15 lb felt paper over the holes will ensure air blocking. Or house wrap. As for the density, figure your volume and then see if it is close to 3 lbs/cf (check that number; perhaps Robert has it on the housewright.com site, or search for it here. I have seen it 30 times, but don't recall.) john
Insulation holes in wood sheathing are normally sealed with pre-cut tapered wooden plugs. The foam may be adequate for air sealing but won't offer any nailbase for the siding. I would ask the contractor to install wooden plugs. He may likely charge extra for this if it was not in the contract.
594 SF of 3½" thick wall with the typical 25% framing factor has a cavity volume of about 130 CF. 16 bags at 30lbs each would give you a density of better than 3.5 PCF, which is excellent.
Depending on what kind of siding material you have, the cheaper contractors might propose just drilling through it and popping in plastic plugs that they say can be painted. Don't do it. Have them remove some of the siding material before drilling.
The bags they used were from Home Depot, and according to the Home Depot website, they are 22.5 lbs, so 16 x 22.5 = 360lbs. 360lbs/130CF = 2.76 lb/CF, plus of the 16 bags they had a garbage bag full of waste. Is this enough of a difference to worry about?
Yes, George. Dense-pack cellulose must be installed to a minimum of 3 pcf.