I'm doing lots of remodelling in my house and I'm considering opening up the exterior walls and replacing the fiberglass insulation. Has the R-value of 4" insulation improved since 1953? If not, I'll just leave the walls alone.
Mike
Well, if it is indeed insulated with fiberglass, the 3 1/2" thickness has gone from the old R11 to R13. But it is probably not fiberglass. Any house of that vintage that I have had the walls out where they have been insulated, used cellulose batts. In every case, they have disintegrated into dust. Do a little exploration on one wall to see what you have. And there is a pretty good chance it isn't insulated at all unless you have reason to believe otherwise.
Dennis
Are there better materials than 1953,,,, Yes. They cost a lot more than fiberglass and cellulose.
think
Assuming what is in there is still in good shape, that is it is still filling the cavities, I don't think you are going to gain much of anything by replacing it with fiberglass. Now if you want to replace it with a foamed in place modern foam, installed by professionals, you could make some noticeable gains, but it is going to be expensive.
: > Mike : : Are there better materials than 1953,,,, Yes. They cost a lot more than : fiberglass and cellulose. : : : I've really been impressed with the "blueboard" insulation lately - per inch it's slightly better than fiberglass numbers and worked wonders on my porches; it also works as a vapor barrier. Cuts easy, but a little more work than 'glas, a little more expensive too. I like no 'glas mess with all out pets around here.
Pop
Fiberglass is apx 3.75R per inch, foamboard goes from R 5 to R 7.2" but it costs alot. It depends if your old insulation was done right, it may be fine but even if done right total R value is not optimal.
If it looks like fiberglass, it could be rock wool.
If it's in reasonable shape, there wouldn't be much of a cost advantage in replacing it.
Mike
I have the blueprints to the house and they call for 4" fiberglass batts in the exterior walls.
How about the pink or blue styrofoam sheets? I Googled and found the blue extruded stuff to be almost R-5 per inch. Three inches of and I'm at R-15. Are there any calculations I can do to see if the increased insulation energy savings will offset the cost of materials?
And since expanding foam was brought up....How come you can buy a small can of it, but you can't get a larger quantity so that you can do larger cavities?
Mike
It's a proven fact that any size window or door will use just a little bit out of the last can of foam. Sometimes it needs just a little bit from the can you left at the store. It's a conspiracy. Actually, for those that don't know, yellow stuff is packaged just big enough to lift a cast iron bathtub exactly 1.83 feet off the floor before it cures, unless the walls and floor are reinforced, and not made out of drywall, then it lifts it 2.47 feet. That's for those that find low tubs hard to get in and out of. In a government study, they found that a large number of expanding foam marketing people used to work at the hot dog bun factory! No joke. 87 million dollars was allocated to the project to find out what the connection is. An anonymous contributor to the study was quoted as saying, "If we all stick together, we can sell a BUNCH of steel cans, plastic straws, and propellant."
You can, fastenal and mcmaster have it, but it is still expensive. Believe it or not it is cheaper to pay to have it installed, as long as they do it right, which is not guaranteed.
If you are not averse to creating new extension jambs for the windows, and doors, think about an inch of blue foam under the sheetrock or under the siding. That would be your best value, since it insulates the studs[which are only less than R 5 total]
If you are working on the outside, removing the siding, then that stuff is good under the siding, but don't try using it to replace the fiberglass, as it will not seal well around the edges and the air leaks around it will cause more heat loss than you might be gaining.
expanding foam can put tremendous forces on whatever contains it. Large areas like walls would be easily blown out by an amateur user.
bill
They had insulation in 1953???? I don't think so.
So ... teach me here if you can: How is the total R not 'optimal'? It's really NBD since it's "just" a porch, but the walls are actually almost warm to the touch, compared to our front porch, which feels cooler and has 5.5" 'glas in the 2 x 6 spaces. So, I'd ass-u-me-d it was an improvement. Both are heated BTW, and make "day rooms" for me (I'm disabled) when I'm having my "bad" days. I'm coming at it from a $ to heat cost, of course. Oh, one's an east, the other a west exposure.
Or am I not understanding your comment?
TIA,
Pop
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