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Old 05-21-2020, 05:27 PM   #1
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Insulating basement that's already framed with electrical


First, let me own my novice DIY status and say I probably screwed up. I bought a new house last year in the Indy area (5b) and immediately went to work finishing the basement. The builder attached batts of insulation to the top half of the poured concrete walls to just below grade. I framed the walls just off those batts, so several inches from the foundation. Didn't consider any other insulation as I assumed like a novice that I'd just insulate the stud cavities after everything was done. It's only recently I've become aware that the preferred option is rigid foam attached to the concrete walls from top to bottom for moisture control. I've now got a 2000 sf basement fully framed with electrical run and I'm wondering what my best and most cost-effective course of action is for insulation. Would appreciate any advice! If it makes a difference, I learned today that the builder used a waterproofing membrane (Hydra-Guard?) on the exterior of the foundation. Also, here's a link to a couple pictures if that helps: https://photos.app.goo.gl/1Kq5uGx6XoicXFBJ9
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Old 05-21-2020, 06:08 PM   #2
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Re: Insulating basement that's already framed with electrical


Are you saying there is concrete behind the lower portion of that pink stuff?
"The builder attached batts of insulation to the top half of the poured concrete walls to just below grade."

Looks like you have a good gap between the framing and the concrete so possibly you will be able to slide in some rigid.

Describe the wall layers where the pink is and how much of a gap do you have?

Bud
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Old 05-21-2020, 07:58 PM   #3
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Re: Insulating basement that's already framed with electrical


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Originally Posted by Bud9051 View Post
Are you saying there is concrete behind the lower portion of that pink stuff?
"The builder attached batts of insulation to the top half of the poured concrete walls to just below grade."

Looks like you have a good gap between the framing and the concrete so possibly you will be able to slide in some rigid.

Describe the wall layers where the pink is and how much of a gap do you have?

Bud
Thanks, Bud. Yes, the fiberglass is attached directly to the concrete with masonry screws and discs. It covers the top half of my wall, or just below grade. It's about 4.5 feet or so of the 9' walls. The bottom half of the wall isn't covered by anything.

The gap between the foundation and framing is about 4" all around. The insulation on the top half is about that thick, so the framing is just off it. I didn't want to compress it at all. Plus framing that far off the wall helped me avoid some obstacles and also ensure nice, straight walls.

Thanks for any opinions on options!
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Old 05-21-2020, 08:18 PM   #4
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Re: Insulating basement that's already framed with electrical


I searched "Hydra-Guard" and found this:
https://www.appliedtechnologies.com/...oofing-system/

"When applied by a Select Waterproofing Contractor the Hydra-Guard Waterproofing System has a 35 Year Limited Warranty on new residential construction foundations."

So is he a select contractor? If so he should be providing you with all the paperwork needed to make that warranty valid.

If he is not, then no warranty and a big question mark on how well his installation will perform.

From my background "waterproofing" is a salesman's promise and not a measure of the performance. There are many additional steps needed.

Aside from my concerns, fiberglass against concrete has long been a poor approach.
Here's some reading.
https://www.buildingscience.com/docu...ts?full_view=1

You have plenty of space so adding rigid between wall and framing is possible, may not need 4". Google Roxul and read up on how it performs in basements.

Bud
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Old 05-21-2020, 08:26 PM   #5
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Re: Insulating basement that's already framed with electrical


You are not on bad shape at all except for the missing fire stop ate the top of the wall.

We build our walls one inch away from the concrete and insulate with fiberglass and do a vapour barrier.

If you don't intend to use a vapour barrier there are electrical boxes with a gasket for that.
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Old 05-21-2020, 08:44 PM   #6
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Re: Insulating basement that's already framed with electrical


Is there a poly film behind this fibreglass?
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Old 05-22-2020, 08:45 AM   #7
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Re: Insulating basement that's already framed with electrical


Quote:
Originally Posted by Bud9051 View Post
I searched "Hydra-Guard" and found this:
https://www.appliedtechnologies.com/...oofing-system/

"When applied by a Select Waterproofing Contractor the Hydra-Guard Waterproofing System has a 35 Year Limited Warranty on new residential construction foundations."

So is he a select contractor? If so he should be providing you with all the paperwork needed to make that warranty valid.

If he is not, then no warranty and a big question mark on how well his installation will perform.

From my background "waterproofing" is a salesman's promise and not a measure of the performance. There are many additional steps needed.

Aside from my concerns, fiberglass against concrete has long been a poor approach.
Here's some reading.
https://www.buildingscience.com/docu...ts?full_view=1

You have plenty of space so adding rigid between wall and framing is possible, may not need 4". Google Roxul and read up on how it performs in basements.

Bud
Thanks again, Bud. I'm leaning heavily towards using 2" EPS for cost-effectiveness. I'm assuming I should remove the fiberglass already installed so that I can use full sheets of foam board on the walls from top to bottom.
I can then reuse the fiberglass in the stud bays afterwards.

Assuming this is a good plan, the fiberglass is attached with masonry screws or nails through big plastic washers. Would I need to remove all those or could I just carefully tear the insulation off and then install the foam right over those. Seems like a huge job on top of an already tricky one, but I obviously want to do the best I can.
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Old 05-22-2020, 08:47 AM   #8
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Re: Insulating basement that's already framed with electrical


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Is there a poly film behind this fibreglass?
No poly or anything behind it. Attached directly to the wall with masonry screws or nails and huge plastic washers. It's probably there just to meet the code requirement of R-10 above grade. I'm learning it's not good to have fiberglass against a concrete wall due to condensation that can form when warm interior air meets the cold wall, so I'm now leaning towards removing this. Any further advice from you or others is so greatly appreciated!
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Old 05-22-2020, 08:55 AM   #9
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Re: Insulating basement that's already framed with electrical


I like the idea of the foam. The whole idea is to seal the wall so moist air does not gt to the cold and you have no condensation to worry about.

You will need air and fire stop at the top of the wall and these boxes with gasket seal the wire and stop all air.

https://www.shdelectric.ca/archives/1240

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Old 05-22-2020, 11:26 AM   #10
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Re: Insulating basement that's already framed with electrical


You are on the right track. Just cut a diamond around each plastic washer if they are tight against the concrete. Fit the rigid foam ae tight as you can against the wall. A piece of 2x6 and a big hammer will seat any of the nail/washers into the foam with no loss of insulation.

If you re-use the old fiberglass don't worry about the holes. the fiber will fill in and you really don't want a vapor barrier on the inside. Allowing the wall to dry to the inside will handle and small amount of moisture that may get in there rather than having it accumulate.

Is that bottom plate of that wall pressure treated? Should be and all nails or fasteners would need to be rated for that wood treatment.

Bud
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Old 05-22-2020, 04:59 PM   #11
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Re: Insulating basement that's already framed with electrical


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Originally Posted by Nealtw View Post
I like the idea of the foam. The whole idea is to seal the wall so moist air does not gt to the cold and you have no condensation to worry about.

You will need air and fire stop at the top of the wall and these boxes with gasket seal the wire and stop all air.

https://www.shdelectric.ca/archives/1240

Thanks again, Nealtw! I'm gonna give it a whirl with a test piece of foam and see if I can thread it through the studs. If I have to remove a piece here and there, so be it...my mistake in the first place!

And yeah, I'd held off on fire blocking at the top plate until I figured out what I was going to do with insulation. I'm planning to use drywall or 3/4" OSB up there.
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Old 05-22-2020, 05:01 PM   #12
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Re: Insulating basement that's already framed with electrical


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Originally Posted by Bud9051 View Post
You are on the right track. Just cut a diamond around each plastic washer if they are tight against the concrete. Fit the rigid foam ae tight as you can against the wall. A piece of 2x6 and a big hammer will seat any of the nail/washers into the foam with no loss of insulation.

If you re-use the old fiberglass don't worry about the holes. the fiber will fill in and you really don't want a vapor barrier on the inside. Allowing the wall to dry to the inside will handle and small amount of moisture that may get in there rather than having it accumulate.

Is that bottom plate of that wall pressure treated? Should be and all nails or fasteners would need to be rated for that wood treatment.

Bud
Thanks so much, Bud! Appreciate the advice on dealing with the washers and old fiberglass. I think I've got a handle on this thanks to all the advice I'm getting on the interwebs!

Bottom plates are all pressure treated and secured with appropriate fasteners. I appreciate you pointing that out for sure.
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Old 05-22-2020, 05:59 PM   #13
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Re: Insulating basement that's already framed with electrical


The Hydra Guard on the outside of the foundation is the vapor barrier.

What if you left the pink fiberglass batt insulation in place and added more insulation of your choice where you desired with no additional vapor barrier?

Then any room air moisture that condensed against the foundation wall in winter will evaporate and come back out in summer when you run the dehumidifier.

If you add a vapor barrier but did not succeed in sealing off the stud bays from the interior absolutely perfectly (hermetically sealed) then any moisture that managed to get behind and against the foundation will probably remain back there forever. This includes walls containing foam board.

For those eavesdropping with batts already installed with the pink fiber glass between the facing paper and the concrete wall, cut holes in the facing paper to make it no longer act as a vapor barrier. Suggest cutting about 25% of the surface area, the most efficient way is probably cutting out patches about 6 inches in diameter.
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Last edited by AllanJ; 05-22-2020 at 06:11 PM.
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