Insulating rim joists- foam

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Donald

Donald

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Near the beach in Delaware
Like many houses with a basement I have many rim joists and they currently have fiberglass insulation stuffed into them. I would like to re-do that with foam insulation, either board or spray.

Has anyone tried the 2 canister spray foam system you can buy for a couple of hundred dollars.

I do not want to make a mess nor waste it if I get hung up and need to stop.

The foam board would take longer but I could take my time.
 
I just did mine a few months ago. Because previous owners just stuffed /crammed fiberglass in there. I ended up taking it all out and spray foamed (Great Stuff) around the cracks and used Roxul for the cavity. The biggest leaks were around the basement windows.
Is there insulation in there now?
 
I can't offer any advise except to say:

If you have threaded studs coming up thru the foundation,
now would be the time to make sure they have 'nuts' on them and that there tight.
Some big washers are good also.
 
Originally Posted By: Warstud
I just did mine a few months ago. Because previous owners just stuffed /crammed fiberglass in there. I ended up taking it all out and spray foamed (Great Stuff) around the cracks and used Roxul for the cavity. The biggest leaks were around the basement windows.
Is there insulation in there now?


Unfaced Batts stuffed into the rim joists.
 
Originally Posted By: larryinnewyork
I can't offer any advise except to say:

If you have threaded studs coming up thru the foundation,
now would be the time to make sure they have 'nuts' on them and that there tight.
Some big washers are good also.


I will check but it would take something mighty powerful to lift a 3 story house off the foundation. I am in the woods so they trees cut the wind unless they get ripped away also.
 
Originally Posted By: Donald
Originally Posted By: Warstud
I just did mine a few months ago. Because previous owners just stuffed /crammed fiberglass in there. I ended up taking it all out and spray foamed (Great Stuff) around the cracks and used Roxul for the cavity. The biggest leaks were around the basement windows.
Is there insulation in there now?


Unfaced Batts stuffed into the rim joists.


Yep... Previous owners stuffed/rolled/ faced insulation in there. Not properly done. It was dirty when I removed it. Which is a tell-tale sign of air filtration.
 
I did this a few years ago on my new build. Builder just stuffed faced batts in the rim joist. I replaced with 2" rigid foam to fit as snug as I could. Then I can spray foamed the edges of the foam board. I then just put the fiberglass batts over the foam board.

If you wanted your rim joists insulated with strictly spray foam, I would have someone come in and do that rather than using small cans. You mention using the 2 bottle system, I think I looked into that but the reviews were not very good.
 
Last edited:
Originally Posted By: larryinnewyork
I can't offer any advise except to say:

If you have threaded studs coming up thru the foundation,
now would be the time to make sure they have 'nuts' on them and that there tight.
Some big washers are good also.


The nuts and washers are installed to keep the walls in place during construction.
If you've got winds strong enough to move a house sideways or lift it off the foundation, those itty-bitty nuts and washers won't stop it from happening.
 
When I renovated my basement I caulked all the joist to stop air penetration and foam board all the the joist and walls.Framed the wall then fiberglass insulation.I taped all the seams on the foam board.
 
I have the same F/G insulation stuffed into the numerous basement joists. Considering the temp in my basement runs 52-60 deg F during the winter (and no more than 75 deg in peak summer), I don't think much outside air is making its way upstairs where we spend 99% of our time. And there's a slider door for the bulkhead and five 55 year old windows to boot. If I were looking for a bang for my buck on house insulation it would be on attic floor (if cold) and any outside gaps underneath the lowest clap boards and/or siding.
 
Originally Posted By: edwardh1
termite company needs to see the rim to inspect for termites, go easy on the foam.

I suspect Oshawa or Upstate NY has less of a termite problem than South Carolina
 
Most places around here don't really have insulation in the joists. If it's too well insulated, you don't get any heat in the basement so your pipes are more likely to freeze.
 
I'd go with foam board myself. I never like to do anything that's really hard to reverse. Foam might seal better but it would be the very devil to get out if you needed to remove it. And who knows why you might want to do that - to deal with water infiltration, inspection for carpenter ants ....

I remember the debacle with urea-formaldehyde foam all too well. And then there was vermiculyte insulation. And for that matter asbestos. In all cases the original problem was compounded by the cost and difficulty of removal.

If you want a really good seal, someone suggested sealing around foam boards with foam. That might be the best of all worlds.
 
Even foam board and sealing with cans of foam is going to be expensive.Cans of foam don't go very far. Buy a case of caulk and fill in all the gaps to stop air infiltration much cheaper.Then u can use foam board or fiberglass insulation on the joist.Much cheaper and works like a charm.
 
I live in Minnesota where it can get windy and really cold. I used the expanding foam on my rim joists around the entire basement. Don't waste your time with foam board - use expanding foam to penetrate and seal every possible crack and opening. I did my whole basement using that stuff and then sprayed the bottom of the subfloor between joists to provide sound insulation from the wood floors above. The unexpected benefit was how solid and quiet the floors seemed when you walked on them; It quieted the floors from both sides.

The product is used was Green Foam which came in 2 large canisters that were the same size as propane tanks. Because of the size of my project, I had 4 of those canisters (they come in pairs and are mixed via hoses that blend the product at the nozzle.) I also ordered a Tyvek Suit and goggles. It's messy - but you get the best possible seal and insulating qualities that you cannot duplicate any other way. Hindsight being 20/20 - I wouldn't do it any other way.

Good luck!
 
Last edited:
Originally Posted By: 757guy
I live in Minnesota where it can get windy and really cold. I used the expanding foam on my rim joists around the entire basement. Don't waste your time with foam board - use expanding foam to penetrate and seal every possible crack and opening. I did my whole basement using that stuff and then sprayed the bottom of the subfloor between joists to provide sound insulation from the wood floors above. The unexpected benefit was how solid and quiet the floors seemed when you walked on them; It quieted the floors from both sides.

The product is used was Green Foam which came in 2 large canisters that were the same size as propane tanks. Because of the size of my project, I had 4 of those canisters (they come in pairs and are mixed via hoses that blend the product at the nozzle.) I also ordered a Tyvek Suit and goggles. It's messy - but you get the best possible seal and insulating qualities that you cannot duplicate any other way. Hindsight being 20/20 - I wouldn't do it any other way.

Good luck!


What tricks are there with the foam? How many joist boxes can a set of tanks do? How long between first use and when the system is too old to use? What about temp?
 
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