DIY insulation in a tight space above foundation

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jeb101
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DIY insulation in a tight space above foundation

Post by jeb101 » Wed Oct 10, 2018 9:00 am

I was hoping for a DIY solution in insulating (properly) the top end of my basement foundation wall. The wall in question has a joist running ~3-4 inch parallel to the foundation, where the house sits, so I can't really put proper insulation in there, the joist ends are all getting roxul / XPS treatment, but currently they just stuffed (and I mean STUFFED) the side of the house with pink fiberglass insulation and it's very breezy.

XPS foam would be great, but I'll have no way to seal it, and I can maybe try ramming roxul in there, but it seems like the wrong way in doing things.

I have 23 ft of this to do, and it's by far the most troublesome side of the house in terms of wind and water permeation.

Simplicity and efficiency, spray foam seems to be the best option, but I'm looking at 1100 after tax.

After going down the internet rabbit hole, I found pour in foam, mix A+B and you get some closed cell foam, but not sure how realistic this would be, I'd have to build a sealed form between that small gap to the wall, and seal it in, hoping I don't get a blow out, but luckily nothing super serious unless it absolutely blows out.

Looking for ideas or your opinion on this if you have suggestions, let me know!

I will be uploading pictures to give you a better idea later this evening.


Cheers


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Shannon
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Re: DIY insulation in a tight space above foundation

Post by Shannon » Wed Oct 10, 2018 10:56 pm

Those are typically very tough areas to insulate really efficiently, because as you know you barely can get your hands in there let alone see what you are doing. What I typically do is install Roxul insulation as best as I can by feel then seal the opening by cutting some two inch foam that is about 2' wider then the opening. Get the pieces up into place flush to or slightly above the bottom of the joist and drive screws through the joists into the foam leaving about a 1/4" gap between the foam and the joist. You can then use canned sprayfoam to seal the perimeter of the foam at the joist and the concrete wall.
Filling with liquid foam will never work right and be a real mess and I see no way that a sprayfoam contractor can truthfully say they did a completely good job with proper coverage in such a tight space.
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jeb101
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Re: DIY insulation in a tight space above foundation

Post by jeb101 » Thu Oct 11, 2018 8:16 am

Shannon wrote:
Wed Oct 10, 2018 10:56 pm
Those are typically very tough areas to insulate really efficiently, because as you know you barely can get your hands in there let alone see what you are doing. What I typically do is install Roxul insulation as best as I can by feel then seal the opening by cutting some two inch foam that is about 2' wider then the opening. Get the pieces up into place flush to or slightly above the bottom of the joist and drive screws through the joists into the foam leaving about a 1/4" gap between the foam and the joist. You can then use canned sprayfoam to seal the perimeter of the foam at the joist and the concrete wall.
Filling with liquid foam will never work right and be a real mess and I see no way that a sprayfoam contractor can truthfully say they did a completely good job with proper coverage in such a tight space.
This is very interesting... I wasn't expecting this answer, I figured spray foam would of been your go to, but wasn't expecting this..

As for spacing, I can fit a hand, but not much else, I got shockingly busy last night and forgot to take a picture for reference. I'll set a reminder to take a picture with a measuring tape.

Glad to hear that you recommend Roxul, cause I have a bunch of it... I assume I "carefully" cram it in to not be too tight though right? Cause like fiberglass I assume, more it compresses, the more of a conductor is becomes, so you lose R value.

To make sure I understand the foam, I basically make a strip that goes from the joist to the top of the foundation then seal it in?

I'm about to start insulating everything in the basement before the cold snap, but it's a tricky beast to deal with as it's a leaky area and want to make sure it's done right. Not to mention needing to make an access portal for the ash trap and whatnot in the basement, which I'm sure I need to use fireproof material vs normal drywall due to it being close to a chimney access (even though not in use).

Cheers

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Shannon
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Re: DIY insulation in a tight space above foundation

Post by Shannon » Thu Oct 11, 2018 8:24 am

Yes any insulation like batts or Roxul does not want to be compressed to much when installed. Just snug fit.
You are correct on the foam strip ,just seal it with spray foam after. This will still give you a cold floor near the wall upstairs in that area if you don't have carpeted floors but really nothing you can do different IMO.
Fire guard drywall would not be a bad idea but if the ash trap is not used anymore it really may be over kill.
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jeb101
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Re: DIY insulation in a tight space above foundation

Post by jeb101 » Thu Oct 11, 2018 8:40 am

Very good to know, thank you for the info! I will post a picture as promised, but sounds like it's gonna be an interesting evening of pulling out the old and cramming in the new.

In your opinion, if I were to have the spray foam guy come in for that end / wall (leaky wall but has delta MS now), how much room do you think he would need between the joist and foundation to get a proper fill in there?

Cheers


Edit: Doing my routine search for cheap insulation, I found out that Crappy Tire has the 200sq frothpacks on sale for 300 (350 retail). Would it be worth going for that? Or do you think the Roxul + foam barrier would suffice?

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Re: DIY insulation in a tight space above foundation

Post by Shannon » Thu Oct 11, 2018 5:28 pm

IMO unless you can actually get your head up in there or I guess maybe even your phone to video what you have done it is not worth it. Without seeing the entire area you are only guessing if it is entirely sealed and covered.
I have been finding that the froth packs are not working well for me and have stopped using them.
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Re: DIY insulation in a tight space above foundation

Post by jeb101 » Fri Oct 12, 2018 8:03 am

Shannon wrote:
Thu Oct 11, 2018 5:28 pm
IMO unless you can actually get your head up in there or I guess maybe even your phone to video what you have done it is not worth it. Without seeing the entire area you are only guessing if it is entirely sealed and covered.
I have been finding that the froth packs are not working well for me and have stopped using them.

As promised, here are some pictures, as well as the area I'm debating if i should spray foam sealed or not. Area had hydraulic cement chipped off to show they used foam leak injection instead of epoxy for a horizontal. Delta MS is on the other side of the wall, and a new drain tile, but want to ensure I don't get more water..

Image
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I was curious, what is it that did not work well for you with the froth packs? From what I can tell though, unless you pre-heat the canisters, and work in a hot room, you're gonna have a bad time (one of the components needs a good chunk of heat (~25c) it seems?) Either way, it's interesting to hear that you stopped using it, makes me rethink my approach.

Cheers

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Re: DIY insulation in a tight space above foundation

Post by Shannon » Fri Oct 12, 2018 8:34 am

Yes that is exactly the problem. When the tanks are not at ideal temps. it seems you don't always get a good even mixture of the two components together. At least that is what I think my problems have been associated with. If I ever use them again I was going to buy a couple of heating pads and tape them around the tanks and keep them turned on.
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Re: DIY insulation in a tight space above foundation

Post by jeb101 » Fri Oct 12, 2018 8:53 am

Good to know.. I have a sous vide water heater / circulator, I may throw both A+B tanks in 25c water for a day then keep em in there as much as possible, keep the temp up and get the most of it. If I do decide to go that route though.

What is your take on the pictures that I have attached? Do you think those cracks and whatnot in the wall may cause issues if I don't seal em in with spray?

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Re: DIY insulation in a tight space above foundation

Post by Shannon » Fri Oct 12, 2018 9:05 am

Let me know how that worked for you with the tanks if you do it.

I see no cracks in those pictures?
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Re: DIY insulation in a tight space above foundation

Post by jeb101 » Fri Oct 12, 2018 10:26 am

Shannon wrote:
Fri Oct 12, 2018 9:05 am
Let me know how that worked for you with the tanks if you do it.

I see no cracks in those pictures?
haha oops, I completely forgot to attach them, this time here they are!

This is just below the pictures I attached above.

Image
Image

The brown thing on the bottom is drywall I removed, so you can ignore that.

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Re: DIY insulation in a tight space above foundation

Post by Shannon » Fri Oct 12, 2018 1:55 pm

It looks to me like they did use an injection system but also filled some misses with foam. I personally doubt you will have any issues if the exterior was done correctly.
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Re: DIY insulation in a tight space above foundation

Post by jeb101 » Tue Oct 16, 2018 8:44 am

Sorry for the late response, the outside has one side below the delta, but one wall it's not, but now above grade (previously below), I will be moving my deck and cleaning out the crack, put some latex modified hydraulic cement in that patch (will be painting the crack with latex beforehand), then parge it. Should seal it good enough for the winter.

The foam is totally me who added that, I was working in the basement for quite a while, after a long and tired day, I had a few beer and a new spray foam gun, I just went foam crazy. I no longer drink and foam. :lol:

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Re: DIY insulation in a tight space above foundation

Post by Shannon » Tue Oct 16, 2018 7:42 pm

You should be fine.

Glad to here you kicked the habit of foaming drunk. :lol: :lol:
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Re: DIY insulation in a tight space above foundation

Post by jeb101 » Fri Oct 19, 2018 12:01 pm

As promised, I am going to be spray foaming the cavity in my basement, and did exactly what I mentioned. I used my immersion cooker, and decided to slow cook my foam!
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It's at 31c for 48h before usage, and it will then be wrapped in a towel and inserted back in the box to keep it's warmth, and a big a$$ heater pointed to it while I spray. Putting in a bunch of heater tonight to spray tomorrow at around 2PM (peak temp outside), 1 220v heater, 1 IR heater, and a in house all in one heat pump. She'll be toasty down there, but I'm too poor to screw up and not get at least 150sq feet from this foam, but it should all work out.

Likely what I will be doing is a hybrid of what you mentioned Shannon, I will be removing the pink insulation, and put some roxul in there, then put a few inches of spray foam where you mentioned making a rigid foam plug, I'd just spray in there, getting 24-30R of insulation in that area, same kind of build as the joist ends.

I'll post after pictures, or WIP pictures if somebody takes some for me as I will be in full smurf suit for it.

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Re: DIY insulation in a tight space above foundation

Post by Shannon » Fri Oct 19, 2018 12:22 pm

Good luck I hope it works out well.
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