basment insulation

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jmp253
Posts: 2
Joined: Tue Sep 11, 2018 9:47 am

basment insulation

Post by jmp253 » Tue Sep 11, 2018 10:03 am

Recently purchased a home, I was planning on taking down all the walls and insulation in the finished part of the basement and doing it back up using Rigid insulation against the cement wall, sealing it tight using tape and foam sealant. Studding it with additional insulation between the studs (either fiberglass or Rockwool) then finishing up with mold resistant drywall. My questions is do you have any recommendations regarding this approach or would you suggest something different?

Also part of the wall has cracks and was injected How would you recommend I insulate this portion as some of the ports are protruding and the wall is no longer flat and even.
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jeb101
Posts: 100
Joined: Fri Jan 12, 2018 8:13 am

Re: basment insulation

Post by jeb101 » Tue Sep 11, 2018 12:13 pm

I'm about to embark in a similar project as yours, and also have an injection area. Since the injection is now dry, I'd take off as much as the putty they used to block the resin / foam, as well as the injector ports, grind it flat as possible, and parge over any divots or cracks formed by removing the putty. Using hydraulic cement as it would also help hold back water in a trouble area. As long as it's not an active leak, and you know it wont leak more, it should be mostly fine.

In case you get mini leaks, and want to save your walls in the future, I'd glue on a 6-8 inch skirt of vapor barrier on the bottom sides of your XPS foam to protect the wood on the floor, save a bit of cash compared to treated 2x4's.simply make sure it has enough overflow for it to go a little under your flooring, assuming you are down to the concrete on floors and walls.

But the main thing before you do any of this, identify any leaks, if any, and make sure they are fixed right, and won't happen again. It's awesome to finish a basement, but it's a royal PITA to have to strip down your hard work because you had a leak. I had a bad drain tile system, and since I was excavating the exterior, I added some delta MS on the outside ensure I won't have to worry about that, of course, I took the extreme measure, but I don't want to have to deal with another flood, they really suck.

I am not a pro, and this is my own opinion / advice.

Cheers

jmp253
Posts: 2
Joined: Tue Sep 11, 2018 9:47 am

Re: basment insulation

Post by jmp253 » Tue Sep 11, 2018 8:30 pm

Thanks for the tip, the injections failed hence why I'm the lucky new owner that gets to do it over again. I'm having the outside excavated and having blue skin put on 4-6 feet each direction from the crack. Filling up the site again and regrading the surrounding area so water runs away from the house. May be overkill but like you said, don't want my hard work going to waste inside.

jeb101
Posts: 100
Joined: Fri Jan 12, 2018 8:13 am

Re: basment insulation

Post by jeb101 » Wed Sep 12, 2018 8:17 am

If you are digging, I suggest you add either spray or rigid insulation below grade on the outside, save 2-3 inches to all your walls in your basement, just need to frame, add batt insulation + vapor barrier and you're set.

I regret so much not doing that when I did it, just didn't have the money at the moment, but if you are planing on doing both in short order, I'd put a few inches of rigid foam, or get a spray foam done. Framing ~1/2 inch from the foundation wall, insulate and vapor barrier, you're laughing.

If the crack you showed is going to be covered by the wrap, and it's not structural, simply chip out all the gunk they added, expand the crack to allow a better bonding of the hydraulic cement. If you want to ensure a good stick, paint the crack and surrounding area with liquid latex (paint section in most hardware stores, or with the masonry stuff in others), that should help everything stick together, you can even go as far as using the latex instead of the water for the concrete.

Best of luck!

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Shannon
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Re: basment insulation

Post by Shannon » Wed Sep 12, 2018 8:35 am

Ya the exterior foam is a good idea if you are digging already but I never like it above grade as it is not easy to keep it from being damaged IMO. And if it does not go right up on the outside it is kinda pointless IMO. You are also left with a lip between it and the exterior finish on the main floors of the home that needs to be properly flashed and finished to prevent water getting behind it.

I think in most cases on a retro fit situation it is safer to put the foam inside.
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