Any better R value in the same space?

[C & E]

It looks like I'm going to have to pull the old T1-11 off the south side of the house due to delamination. While I'm torn down to the insulation is there a material that would use the same space as the old fiberglass insulation (1973 construction)? The southern exposure causes the room to heat up badly in the summer. I'm thinking a closed cell foam or a spray on. Or, isn't it worth it?

[Robert Neville]

You have to do the numbers for your area to say whether it's worth it or not. Closed cell foam does have slightly higher R values than open cell, but eventally there will be a leak and open cell is purportedly better for passing the water through when closed cell will hold it in the wall where it will cause mold and rot.

Also - R value is not the primary consideration. You might also consider a hybrid approach - better economics. Spray a small layer of foam for the sealing properties and use unfaced fiberglass to fill the cavity.

[bob haller]

sprayed closed cell foam is likely twice the R value as old fiberglass.

Foam R6 or R7...... plus it seals all the cracks etc.

you could fill the cavatiys with foam and add a layer of foam over the entire wall too for even better efficency

thats pretty common when people reside here

[JIMMIE]

I had a warm wall like that and hung prefab fence panels on it as a solar shield. Looks good works even better.

Jimmie

[ransley]

Fiberglass is about R 3.75" spray on foams go from about R 5"-R-

7.2". Foamboarn from R5"-R7,2" and the 7.2" is foilfaced for the additional benefit of a radiant barrier. It makes a big difference using foam and spray on will seal all air infiltration, it is worth it, but consider the R7.2 foilfaced and caulking the first and last sheet to stop air infiltration.

[Jim Elbrecht]

'Worth it' depends on where you live, cost of heating/cooling and how much value you put on comfort.

Is there a chance you could add High-R sheathing before the T-111? I would at least look into a highly reflective barrier. You mention heat entrance as a major concern so the materials available to you are likely different from those I'm familiar with. Here we battle to keep heat in- not reflect it back out.

Have some local insulation contractors come out and make suggestions. Jim

[bob haller]

OP could make that wall thicker by say foaming the cavaties then adding foamboard for extra R7.

if wall is 2 by 4 he could take current old fiberglass 3 inch from about R10

to a much cozier and better sealed R 28 plus the radiant barrier.

caution should be used!! he might like it so much he decides to upgrade the entire house:)

there are heat loss calculators that can evaluate the energy savings on the different insdulations

[stan]

And plant trees/bushes! They also convert carbon dioxide into wood!

[Steve Barker]

Wet sprayed in place cellulose is the best way to go. Will stop air infiltration and it fits all irregular spaces around wiring, plumbing etc. Even having it drilled and filled after the siding goes on will work also.

s

[C & E]

Thanks for the replies so far, everyone. Let me fill in some of the blanks I left and some of the Q's that you have. This is a rancher with the narrow, 28' wall, with a hip roof which face south. There are two 30"x42" windows and a door (unused) on the wall. So, the hip roof is an issue with heatign but I have 12" of insulation up there. The windows are 8 years old and have a high 'E' coating (or is it low - I've forgotten) and argon gas between the panels. I had also thought of foil faced foam board over what ever I use for insulation but there is going to be an issue with covering the corners since this side will protrude further than the original other two adjacent walls. So, now I'm thinking, remove the old glass, spray in foam, run a treated piece of lumber along the bottom to keep insects from burrowing into the foam board, wrap with Tyvek, add the foil-faced foam board and replace the T1-11.

Hey bob, you said, "OP could make that wall thicker by say foaming the cavaties then, adding foamboard for extra R7. if wall is 2 by 4 he could take current old fiberglass 3 inch from about R10 to a much cozier and better sealed R 28 plus the radiant barrier." You're right about the 2 x 4 walls. How thick is the foam that you are considering that would take me out to R 28? I had considered adding another 2 x 4 to the existing ones to increase the cavity to 7" but that would kill any overhang and make the place pretty ugly. I'm looking for the fine line between efficiency and design.

Steve, thanks for the wet cellulose reminder! We have a new guy in town doing that. It would probably eliminate the Tyvek. Now, as for asking contractors, I've been doing that for years and the pat answer is, "I'll do what ya want".

Thanks - more ideas are welcome. I'm beginning to develope a plan thanks to you.

[Stormin Mormon]

Give Al Gore a smile. Reduce the carbon dioxide content of the atmosphere.

[bob haller]

the 2 x 4

as for asking

n thanks to

my point is that replacing the fiberglass, its likely just over R3 per inch. with closed cell expanding foam R7 gains you about R4 per inch so 3 inches is a R12 gain:)

or a total of R 21.

then add foam board with radiant barrier that adds about R7 per inch so 2 inches is a R14 gain

so the combined effort would net about a R 35:) plus you gain the radiant barrier.

locally most people residing are adding the foam board as part of job.

plus it covers the studs too for better insulation

so overall gain of

[bob haller]

as

more clearly existing fiberglass about R10

foam and board R35 combined a substantial gain