# Rim joist insulation (odd space)



## flofloflo (Jan 4, 2019)

Hello and happy new year everyone, 

After having an energy audit done on my house, it was recommended (among other things) that I air seal and insulate the foundation headers of my furnace room. I called a guy for a quote, but they won't move for less than $1000 and the space that I have to insulate is actually pretty small. Unfortunately, it's letting a significant amount of air in, so I'd really like to tackle this myself and learn a few things along the way 

I have done a bit of research and watched a fair amount of videos on the topic, but I'm still not sure how to handle this, given the odd shape of the space to insulate. The house is 100+ years old, "double brick" style.

There are two parts of this. First, I need to fix a few holes on the interior layer or bricks. I have not looked into this too much, but I'm pretty sure I can get away with a bit of caulking.

The other part is more challenging and this is where I could use your opinion. My headers have a bunch of pipes and wires going everywhere (see pictures). It will make it hard to do a clean job with fibreglass insulation (it may still be possible) and I don't know if I can solve this with a can of spray foam from the store. Given the size of the job (I only need to seal the space between three joists), would you have a recommendation for me?

Note that I'm okay for some short / medium term solution as this room is unfinished and I will end up re-doing it eventually. I will look into fully insulating the room at that point.
Also note that the last picture (with the two copper pipes) is a zoom on the space between the rightmost joist on the first picture and the bathroom that's behind the green-ish wall.

Being a complete beginner on anything insulation related (or really house related), I'll take any advice 

Thanks in advance.


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## nobbyv (May 30, 2018)

Might take you 2-3 cans of foam, but that's your best bet. Pretty tough to screw up and will run you under $25.


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## That Guy (Aug 19, 2017)

Id use the spray foam to seal it up, and then add paper backed fiberglass for good measure...

now, to cut the fiberglass the easy way...

take a 2x4 place it on top of the fiberglass paper side up... using a utility knife, cut along the 2x that your kneeling on, with out cutting yourself... a piece about 2"s longer than your joists are tall should do the trick

buy the 2 pack of stanley 99e utility knives.. dont worry theres 3 'free' blades in each knife

as far as caulk, skip the crap from home depot, the stuff is garbage, go to sherwin williams and buy some 850, and a dripless caulk gun

while at sherwin williams, open a home owner account, and use real paint going forward.


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## flofloflo (Jan 4, 2019)

Thanks both for your replies, it's very helpful.

Specifically about the can of spray foam, is it usually okay to do this in a furnace room? Or are there usually rules about covering it up?


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## Bud9051 (Nov 11, 2015)

Another approach could be "rope caulk" It comes in a roll where you can separate smaller beads and form it like clay and push it into place. Can foam is not real easy to use in awkward places and as you asked may need to be covered with a thermal protective layer. Once you have sealed all air leaks then stuff the cavities with Roxul insulation. much denser than fiberglass and easy to cut.

I can't get more specific from the pictures provided, not sure what is on the other side and where some of those pipes go. But as you said, when it is cold you can feel the air coming in. Tube caulking or rope caulking for small areas may work well for you.

Note, This is just the furnace room, how about the rest of the foundation, does it leak as bad and is just not accessible from inside?

Bud


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## ront02769 (Nov 28, 2008)

Use great stuff fireblock. More expensive than the other but made to insulate around hot pipes.


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## carpdad (Oct 11, 2010)

First would be finding the air that's coming in. If you block off just that area, air may find its way upstairs.:smile: Can you check outside for holes or such? 

Its also possible to create moisture problems by using insulations that is a vapor barrier. If you stop the air leak, they all become vapor barriers, so you want to learn your building first. Example, if you put a foam board against the bricks, what happens to the joists touching the bricks? How much moisture is acceptable and will it dry out?



As such, you may want to seal the biggest air leaks but not go crazy with the air sealing until you know more about your house. As bud noted, I think the mineral wool insulation, stuffed tightly between the pipes, would be the safe choice.


Can foam doesn't set up in a flash, esp in a colder temps. If you spray now around those pipes, the foam could remain runny and you can end up with a mess. If using foam, stuff some insulation far in so you have some sort of a backer. Then spray in small amount, let it set and keep adding and letting it set. Keep the cans in warmer rooms and shake well before using. You can also join two pipes together by rimming one pipe end. Longer tube is handy in tighter spaces. If you don't use the whole can (try to use the whole thing), leave the trigger on and let the foam set up. This protects the spout and you can reuse it at least within a week. Acetone cleans up the foam.


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