Should I blow-in insulation in my walls on my older home?

Question

I am starting to remodel the exterior of my home.  I work on a low amount of cash flow, but figured I would tackle this job one side at a time.  The first section of the house was build in early 1900, but was added onto in about 1930, and again in around 1960. The house was last sided with Masonite in the early near the 90's and the Masonite is rotting.

I tore down a small section to find tar paper under the Masonite, then OSB, then tar paper, then wood lap siding.  There is nothing behind the wood lap siding, they are nailed directly to the studs.  The walls lack insulation. The inside of the house has already been remodeled (well, sheetrock over the top of plaster).

So my choices now are to rip off the wood siding, fill with batt insulation, and install new OSB, install insulation board, and then house wrap before doing vinyl siding? The batts would have to be installed with the vaper barrier outward and probably wouldn't be to effective.

Or leave the wood siding, fill walls with cellulose, install OSB, then insulation board, then housewrap.

kydmystery · Accepted Answer

The batts would have to be installed with the vaper barrier outward and probably wouldn't be to effective.

in my opinion and experience it does not matter if the the batts have paper or not I've installed it both ways paper in, paper out even no paper at all,. blown in works fine also. The whole vapor barrier thing is vastly over rated, in my opinion. Concentrate your time and money on installing insulation correctly and the right amount (thickness etc). There are videos on you tube showing how to properly install. batt insulation.(dont cut corners when insulating)) Studies I;ve seen don't convince me the vapor thing is even worth wasting time and money on. But it may be required in some areas if so follow local codes.

I say the more air tight a wall the more mold and mildew you have because despite your best efforts moisture WILL get in. The question is CAN it get OUT? That requires good air circulation.

Mongo Khan · Answer

You could use unfaced fiberglas batts inside the studs, then OSB for sheathing, then vapor barrier(Tyvek House Wrap) then siding. Vapor barrier is designed to breath, That means allowing humidity to escape which minimizes condensation. 
If you add foam board, then you would lose the purpose of the vapor barrier. I would lean more toward avoiding condensation than toward containing heat in particular in older homes. I wouldn't worry much about using spray foam to hold the fiberglass in place as long as it isn't a solid fill. Be careful with that stuff as it expands and can blowout walls. Use the limited expansion type.

bob · Answer

Another choice, 2 inch foam on the outside of the house. You can put a vapor barrier inside. Blow in with no vapor barrier seems  like a terrible idea.Same with batts with the vapor barrier outside.If you take the siding off, you could put a vapor barrier on the inside of the batts , following the studs, you just have to leave enough slack so the batts go all the way in. I would get a stucco company do do the foam and stucco, lots of buildings are done that way. New deeper windows aren't so expensive.

misssassyaz · Answer

"moisture WILL get in. The question is CAN it get OUT?"

Wow never thought about it that way, good point.

Trending News

Should I blow-in insulation in my walls on my older home?

4 Answers