1940's Brick home insulation question

[crankshaftdan II]

While installing additional electrical outlets in older brick home, outer walls only have air space between outer brick wall with celotex and inner wall of drywall board with skim coat of plaster. Is it the best selection to have insulation contractor bore holes in attic floors and foam or blow in treated celulose with fire retardent or other insulation? Anyone come across this senario? It is not feasable to gut interior outer walls to get maximum insulation in this house. By blowing in or foaming do you risk a condensation problem by eliminating the dead air space? The ceiling has blown-in celuose insulation blown inbetween floor joists and were capped with two inch plugs. Any comments or suggestions appreciated. Thanks

 

[Falcon67]

Good question. Our house is not brick, but was built in 1926. I debated about pulling the paneling off the inside, drilling holes and blowing into the wall cavities. Then I considered pulling off some strips of siding outside and blowing it in that way. But with no vapor or moisture barrier under the outside sheathing, I finally chickened out on blown in. I just went ahead and ripped off the siding from the base plate to nearly the top plate and put in bats and protected that with overlapping tar paper. It was easier - sorta, better mostly because of no external vapor barrier - than gutting the inside walls and re-sheet rocking. However - given a little more $$$ I would have done the wreck out myself, paid a wall crew and had a better inside finish to the house.

With brick, if there are no cracks and there is at least something between the brick and the wall cavity, blown in should work. Foam is an option, but the contractor better get a good reading on each wall cavity or you'll be replacing sheet rock anyway. However - Not sure how you'd expect anyone to get to the top of the outside walls to cut a hole in the plate without pulling the roof.

One other thing - there may not be any fireblocking in there, then again there may be who knows what in the walls. I tore off (so far - not done yet LOL) about 100 linear feet of siding and I found all kinds of weird building BS in the walls. Enough that blown in would have been a serious waste of time. And the 18' of outside wall along the kitchen was a fricken nightmare of boards, spacers, blocks, stubs, abandoned outlets and whatnot. Also, you can only get under your windows with a hole on the inside.

If the house is worth the effort, I'd strongly consider tearing out the wallboard, upgrading any electrical possible and adding in the insulation. Another option - A good brick mason could probably remove several of the outside bricks near the top of the wall to allow the blow in, then match the motar and replace.

 

[lilredex]

That is pretty common construction around here (from the 30-60's+) when oil heat was "free". Doubt you would gain anything by adding just an inch of insulation to that space.

Last house we had like that, we built new interior walls on top of the old ones with 2" styrofoam (so not to eat up a lot of interior space) and new drywall. Increased that to 4" inches in the basement as most was above ground. Did the trick, cutting the heating bill by close to 50%.

Our present house has the same wall structure, but we just live with it 'cause it has fancy plaster we don't wish to lose with new walls. We have a wood stove in the basement which burns constantly (with "free" wood) and that helps out with the $$$.

Both houses were built in 1958.

 

[jkeyser14]

I just bought a 1953 house. Brick and cinderblock construction. I had the same thing with 1" air gap between plaster walls and exterior walls. I was going though $400 in heating oil a month last winter. As a result I am going room by room and ripping out the plaster, framing the walls, and insulating. I'm also using this as an opportunity to add more electrical outlets and cable/ethernet jacks. I see no reason not to use blow in, but you'll only get about R3 with one inch of space.