Basement reno

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awdturbo2g
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Basement reno

Post by awdturbo2g » Tue Sep 03, 2019 4:42 pm

Hello everyone,

I am starting to redo an already partially finished basement due to some moisture issues and general poor quality job done previously. I began by tearing down all of the wood paneling to find the concrete foundation insulated with faced batt insulation installed between the studs, no barrier on the concrete and the kraft paper poorly stapled on the living area side with lots of gaps. Id like to add a 1" rigid foam board onto the concrete surface but the studs are installed basically right up against the concrete leaving little to no room to install the rigid foam behind the studs. I am really hoping not to re-frame the entire basement so i wanted to cut the rigid foam boards to fit between the studs and spray can foam the gaps around each board. The first minor issue arises with what to do in the tiny space behind each stud? maybe just shoot some spray foam into the space best i can? The second issue is with after installing the 1" rigid foam that only leaves 2.5" left for the batt insulation , i don't want to squeeze the 3.5" batts into the space and compromise the effectiveness of the insulation. Do they sell skinnier batts? Id eventually like to finish off with a 6mil poly barrier before the drywall. Any suggestions for the 2 issues i'm having would be appreciated. Thank you

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Shannon
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Re: Basement reno

Post by Shannon » Tue Sep 03, 2019 9:20 pm

Knocking down the walls and starting over would be my preference ,especially since the wood has been in contact with not only the concrete walls but the damp concrete floor as well. You are very likely to find mould and mildew issues on areas of that old framing from this contact.

Is it a possibility to cut the walls free from the floor and ceiling and moving them inward? This can be a pain especially if the wiring has no extra wire to allow any movement but it would give you a much better and efficient insulation quality.I would pull them 1-1/2" to 2" forward if possible.

If this is not a possibility I would price out having it spray foamed.

Lastly I would go the route you suggested and put rigid between the studs ,sprayfoam the back side of wood and seal to the rigid foam pieces. You could then use R12 batts torn in half thickness wise. This is by far the worst option IMO.
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awdturbo2g
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Re: Basement reno

Post by awdturbo2g » Wed Sep 04, 2019 4:46 am

Hello Shannon. After inspecting the area further, it looks like the bottom plate in contact with the concrete floor ( non treated lumber of course...) is showing signs of damage from moisture so this will need to be replaced for sure. I thought about moving all the walls in a few inches but now with the bottom plate issue id have to replace it anyway. I was hoping i wouldn't have to re frame but i want to make sure it is done the best way possible so looks like ill be doing that. Thank you for the response and all your You Tube videos have been very helpful.

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Shannon
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Re: Basement reno

Post by Shannon » Wed Sep 04, 2019 6:34 am

It is possible to cut off just the bottom of each stud just above the plate or even 1/4" or so of the studs and remove the plate. Then fasten the new plate in the new position and pull wall forward and attach each stud to the plate. If the studs are ok.
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awdturbo2g
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Re: Basement reno

Post by awdturbo2g » Wed Sep 11, 2019 4:43 pm

So i ended up taking it all down. Wow am i glad i did, there was significant mold behind each stud and in corners. Now that it is all down my plan is to install 2" Dow super tuff R ( R-13) rigid foam on all of the concrete, then purchase a 200 sqft froth pack to spray foam all the rim joist areas that are difficult to insulate. My questions are since the rigid foam has a water vapor permeance of <.03 i shouldn't need an additional poly vapor barrier installed, also the R13 should be sufficient for the insulation value of the walls. So do i just go the cheaper route with the walls and do 2x2's 16OC and no batts?

DanM
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Re: Basement reno

Post by DanM » Wed Sep 11, 2019 6:36 pm

I wouldn't go the cheaper route with 2x2's, stick with 2x4s. 2x2s love to bend, twist, and warp and the drywall will end up wavy. The waviness will only get worse with time. As for skipping the batts I would say it depends on your climate. The further south you are the more likely I would say skip it. If you live somewhere where winter is an issue I would definitely put the batts in, you're better off doing it now while everything's open than deciding down the road that the basement is too cold.

awdturbo2g
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Re: Basement reno

Post by awdturbo2g » Wed Sep 11, 2019 7:43 pm

Thank you DanM. You are right, i will regret it later if i take short cuts now. With batts and 2x4 I will end up with about R26 in the walls so should be very well insulated. So no additional vapor barrier needed with the 2" rigid foam correct?

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Shannon
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Re: Basement reno

Post by Shannon » Wed Sep 11, 2019 8:30 pm

Many areas will allow the vapour barrier to be skipped if the 2' foam is used and sealed well. You would have to check with your local inspection office about that.
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Shannon
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Re: Basement reno

Post by Shannon » Wed Sep 11, 2019 8:34 pm

By the way I agree with Dan completely on the extra batts of insulation.
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