Contractor Talk - Professional Construction and Remodeling Forum banner
1 - 10 of 10 Posts

·
Registered
Joined
·
299 Posts
Discussion Starter · #1 ·
If a home built in the 1950's or 1960's has some insulation in the walls( fiberglass), can you still use blown in cellulose or polyurethane in the walls WITHOUT removing the fiberglass?
What is/ was the usual Rvalue of the insulation back in those days( r13)?
If so, will it make a noticable difference? Is this done often and is it common? Most folks dont want to rip their walls apart.
 

·
General Contractor
Joined
·
8,083 Posts
If a home built in the 1950's or 1960's has some insulation in the walls( fiberglass), can you still use blown in cellulose or polyurethane in the walls WITHOUT removing the fiberglass?
What is/ was the usual Rvalue of the insulation back in those days( r13)?
If so, will it make a noticable difference? Is this done often and is it common? Most folks dont want to rip their walls apart.
If you already have insulation in the wall, not much you can put in there without the use of evasive method. Blow-in insulation will not work with existing insulation filling the wall cavity.

The only thing you can really do without tearing out the walls, is change windows to prevent heat loss, insulate the attic space with another layer, improve heating system, re-siding with foam insulation, etc.

If you have older siding, take a piece off and see if you have exterior sheeting. If not, and if your budget allows, you can insulate the wall cavity from the outside as you go with house re-siding and put new sheeting at the same time.
We did a job like this a while back on older home re-siding and it made a big difference.
 

·
Sean
Joined
·
5,533 Posts
Pourable - it can work if installed properly & verified by Infrared during the pour as the heat generated will show you if the whole cavity is being filled. You should also reverify after it has been completed with a blower door infrared. With that there is one major caveat & issue - long term durability which many says it fails at - namely shrinking so I would probably skip

Dense pack - it can also work if you have an experienced crew but it is very tough to pull off due to obstructions & the product. Infrared can also be your friend as it may point out some obstructions help verify that you don't have voids (especially coupled with the blower door)

A few items for older homes - the electric, what is it & what type of shape? Are there any water intrusion issues? Both of these need to be addressed up front or you have just created a big mess & issue.

The best way to handle older walls like this is to remove & reinstall (also taking care of those issues listed above) &/or by adding foam board to the exterior (two layers offset preferably)
 

·
Registered
Joined
·
3 Posts
As a former remodeling contractor for the last 17 years I can tell you that often there is little insulation in a home of your age. You will need to gain access to inspect to know for sure. Blow in insulation works very poorly in my opinion as it doesn't address gaps which it where most energy loss occurs. We would remove all siding and sheathing to apply a closed cell spray foam. A big expense I know but in combination with proper attic insulation we would save folks almost 70% on energy bills.

For more information please visit our web site www.montanafoam.com

good luck
 

·
Registered
Joined
·
299 Posts
Discussion Starter · #8 ·
Even if there is some batt insulation, blowing in cellulose could compress the fiberglass rendering its Rvalue very low. That said, the Rvalue on the batt is so small, wouldnt it be better to just add some cellulose?
This is assuming the HO does not want to rip off his sheathng.
 

·
Registered
Joined
·
22 Posts
If you can get your insulation hose to the top and bottom of each bay, then yes you can easily blow the wall. Sometimes you may have to use a two hole method versus a one hole method.
 

·
Box Builder
Joined
·
6,320 Posts
I don't see why a wall cavity couldn't be dense packed with crappy batts already in place. It will just compress the batts, but the cellulose will be beneficial anyway. I'm sure you'll have a few spots here and there that the cellulose won't get to.
 
1 - 10 of 10 Posts
Top