Professional advice needed! Basement insulation

3 years ago

Hi, Houzz community

You have been super helpful giving me ideas with previous design dilemmas and challenges. Hope I can get some expert advice here again!

We are adding an exit door to backyard by opening the basement concrete wall. Our house was built in 2015, and builder had insulated like below. Are these called blanket wraps? We don’t feel like we need any additional insulation.

That said, since we are opening a hole here and had to take out the insulation for this wall.

Question is: what is best insulation in this case?
Our basement is almost all above grade with only 1.5’ below grade. And we don’t have any water or moisture issues in the last 7 years.

Should we keep existing insulation and add frame right next to it? Or should we take these out use digit foam insulation glued to concrete and then frame? That will be a lot more costly.

Thanks a lot!

Wen

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Comments (6)

PRO
GN Builders L.L.C
3 years ago
Yes, keep it... Unless money burns a hole in your pocket and you don't have anything else to spend it on.
worthy
3 years ago

The building scientists at Building Science Corp. dub it the "diaper." See here.

Still cheap and Code approved in most places; I used fg behind plastic for many homes as well when I didn't know any better.

But if I had access to it, I'd remove it in an instant and replace it with EPS (expanded polystyrene) or XPS (extruded polystyrene) boards affixed to the concrete by glue or concrete screws on top of horizontal caulking to stop air currents behind the boards.
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PRO
GN Builders L.L.C
3 years ago
If waterproofing was applied to the exterior of the foundation and most likely it was on a house that was built in 2015 you can put your wall right up to it.
3onthetree
3 years ago
The batt insulation blankets are for a builder to meet energy codes for an unfinished storage basement. They are not concerned with how that insulation performs when finishing a basement to living space. The concern is not water from grade coming through the wall per se; as in leading to basement leaks. It is condensation issues which cause mold behind your finished walls. This occurs when warmer basement air hits the cold concrete wall (or can be vice versa depending on situation and climate). The critical points are how airtight or if space exists for air to flow behind your wall. Worthy has given the best current advice for basement insulating via the Building Science links.
laura222
Original Author
3 years ago
It is interesting that even here people have different views on the use of blanket insulation. Still haven’t decided on what to do with the blanket insulation. Thank you everyone!
3onthetree
3 years ago
I think you missed the point of what I wrote. If scrim-wrapped blanket insulation were the right product for wall insulation, it would be used in all enclosed walls, not just open unfinished basements or open ceiling warehouses.

I have gutted too many dank, stinky, moldy basements with batt insulation and all the air gaps behind/around it. I will never go back to batt against concrete in a basement. The information from Joe Lstiburek is expert, technical advice from investigations and studies for the building industry, not haphazard guesses made by a DIYer or "this is what I do where I live." I have a bunch of framed papers on my wall that I attained by learning from other experts, so I have no problem following his work with this issue.