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how do i figure out how to insulate my walls and what's behind them?

how do i figure out how to insulate my walls and what's behind them?


Old 06-16-09, 09:56 AM
Thread Starter
Join Date: Oct 2004
Location: PA
Posts: 1,838
how do i figure out how to insulate my walls and what's behind them?

Silly question but when the energy auditor was here last year, he told me it's not worth insulating my walls. He said seal up the attic, lightswitches and crawlspace and ill be fine. Maybe he was talking about his costs of doing the walls, i'm unsure.

Anyway, i'm painting a few rooms this year so nows the time if ever that i will insulate. But how do you know what's behind the walls? I have plaster and years ago i tried to fish a wire from my attic thru an interior wall and it kept hitting what appeared to be horizontal strips. So i cant even fish lines in my house. It seems to be a closed up wall if you get my meaning.

I'm far from an expert so i may be wrong but i'm wondering, how do you figure out whats behind the walls and how to insulate it? I'm not gonna take a saw and do a 6ft high hole in the wall lol.

when i was a kid i remember my dad drilling 100s of holes in the wall and bringing home boxes of foam from the store. I hope thats not what i have to look forward to lol. But even if it is, how do you know if the foam is being blocked by any wooden strips that apparently I have with my plaster?
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Old 06-16-09, 11:41 AM
diyplank's Avatar
Join Date: Feb 2006
Location: Williamsport
Posts: 713
You can blow in insulation. Its called Cellulose. You can rent the machine from home depot or lowes and buy it all there. I insulated my walls and attic for about 800 bucks. I drilled holes under my wood lap siding and blew it in from there. Works great, and I noticed a big difference in heating oil usage. I would recommend the walls, but also do what the auditor said and seal up the attic and insulate that. But take into consideration that you don't wanna block any venting like soffit vents.

Blowing it from the inside will be messy but it is do-able. Hope this helps.

I can't tell ya how to tell what is in your wall space! Maybe drill a hole if you can from the outside of the house and fish a wire round and see where it goes.

Good luck
Old 06-16-09, 11:58 AM
Thread Starter
Join Date: Oct 2004
Location: PA
Posts: 1,838
I like the blow in idea. But can it be compressed? I really have no idea what it looks like under my attic floor but do you just fill it up to the top of the joists or should you be smashing it down with floorboards? I'm hoping/assuming there's a large gap under the floor but just dont know at this point.

regarding the walls..well i'd rather drill inside vs outside the house. I can patch plaster but i cant fix permastone lol
Old 06-16-09, 12:12 PM
Join Date: Mar 2009
Location: WA
Posts: 1,167
An older house always had plaster with blocking half-way up. You can pull a recep. cover on an outside wall and fish a stiff wire up to find the height. Generally, they are within 1-1/2" staggered horizontal line. You could hire a contractor who has a scope, even H.D. sells them.

RIDGID SeeSnake micro - 26743 at The Home Depot Be safe, G
Old 06-16-09, 12:26 PM
Join Date: Oct 2008
Location: New England
Posts: 9,990
Hi LD, your previous audit should have determined what is in there for insulation if anything. If nothing, I can't imagine him/her stating it would not be worth adding some, as walls are one of the high value areas to insulate. Give us some background.

How old is the house?
How thich are the walls?
Peek along side a receptical box and do you see any insulation?
Are there any cavities in the attic where you can see down into a wall area, like maybe a chimney chase?
Or from the basement around pipes or bathtub.

If no insulation, then as stated above, consider blown cellulose.

Do you feel drafts around the windows in the winter? It may be worthwhile to pull the trim and seal with a zero expansion foam.

An infrared camera will point out the location of cross braces, but when you drill in preperation to blow in the insulation, a fish wire will tell you where the bottom is. Then drill another hole below the block and repeat.

Old 06-17-09, 08:09 PM
diyplank's Avatar
Join Date: Feb 2006
Location: Williamsport
Posts: 713
Yeah I wouldn't wanna drill through that either! About your attic, is there a floor up there? If so, that is setting on floor joists, which are probably 10 to 12 inches in height. So you can fill in between these w/ cellulose!
If there isn't a floor and you do not need it for storage, just start blowing cellulose up there about 17-20 inches thick. That is what I needed, just depends on where you live. I only have 10" the height of my joists. I have a floor and alot of storage space.
If you have a floor, can you cut a section of it up down the center? If so, do that, shove the hose from the machine all the way back until it stops. Takes some fishing around do to elec. wiring, etc, and let the cellulose flow! Its messy, so wear a mask, a good one! Not the cheap paper jobbies you can get for 3 dollars for 5 of them.
Make sure you do not block your soffit vents if you have any!!!! If you have them, then you have to install rafter vents!!

If you blow cellulose in your walls from the inside, leave the machine on the outside. Like I said, its dustier than hell!!! When you rent the machine, make sure you ask for a reducer. It reduces the 3" hose down to around 1 3/4". I drilled 1 7/8" holes under my siding when I did my walls. Filled them w/ dowels and caulked them so they would stay in place. Worked out great!!

Hope this helps. Good Luck

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