Insulating split level basement

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SarahS
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Insulating split level basement

Post by SarahS » Wed Sep 05, 2018 11:23 pm

Question about split level basement insulation in dryer climate (Kelowna BC):

Our basement is dry (i.e no signs of moisture or mold when we took down existing drywall - 1972 home).

1) Should we remove the poly over the exisitng insulation before adding more insulation? (In above grade part of wall)

2) is it ok to use fibreglass batts directly on the foundation wall between the framing?

Many thanks for all the helpful videos!
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Shannon
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Re: Insulating split level basement

Post by Shannon » Thu Sep 06, 2018 6:56 am

Remove the poly from about 6" above the concrete . Leave the lower area , this will keep the lower insulation from getting damp from any moisture that travels through the concrete. Do not seal any of the lower poly. You can then insulate the entire wall with batt insulation
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SarahS
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Re: Insulating split level basement

Post by SarahS » Thu Sep 06, 2018 3:05 pm

Great, thanks!

Do you mean do not seal the lower poly with acoustical sealant?

Also, does it make sense to add another layer of insulation in the above grade section, or to leave an airspace? (I watched your video about insulated a split-level and using R20 insulation on the above grade part, but we already have the old R10 or whatever insulation, and wondering if we should add another layer or if an airspace is ok?)

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Shannon
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Re: Insulating split level basement

Post by Shannon » Thu Sep 06, 2018 9:27 pm

The old poly against the concrete does not get sealed.
I would add the extra layer of insulation R10 really is not enough .
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SarahS
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Re: Insulating split level basement

Post by SarahS » Fri Sep 07, 2018 9:08 am

Thanks! Just realized my photo was not great...

There is no poly against the foundation wall.

Do you think spray foam against the concrete wall then batt insulation in the above portion makes sense?

Originally when we bought the house a year ago the drywall was just glued directly on the concrete wall :o . Then there was a ledge and more drywall against the upper wall.

We had the 2x4 wall built by an old-school carpenter friend - i guess the standard pracitce here used to be insulation against the foundation wall with poly overtop. But now reading more we are thinking we need to have some moisture protection against the foundation (interior side). However there were no signs of moisture in the basement when we pulled all the walls off.
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Shannon
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Re: Insulating split level basement

Post by Shannon » Fri Sep 07, 2018 7:32 pm

Oh sorry I thought it looked like there was.
Anyways remove the upper poly for sure. Moisture barriers against the concrete is pretty widely accepted now in many areas. You are in Kelowna so frost forming is not likely as much of a concern and that IMO is the biggest culprit of needing it.
if I was you I would not use sparkly foam unless that is really what you want. If you could do the entire wall it makes sense but in your case I would use Roxul insulation in the lower part and batt above . Roxul is really not effect by moisture , so that’s what I would do.
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SarahS
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Re: Insulating split level basement

Post by SarahS » Tue Sep 18, 2018 10:41 pm

Thnaks Shannon. We’ve finished the bottom half with Roxsul. Still need to rip off the old poly.

Wondering if it makes sense to put two more layers of batt insulation on the top half? (I.e instead of just one extra layer on top of the Roxsul?). My father-in-law has a bunch of extra from a building project.
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hcpatel78
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Re: Insulating split level basement

Post by hcpatel78 » Wed Sep 19, 2018 8:30 am

The top half remains outside of the land. I would put it. Per energy.gov website maximum heat loss is at the top half where the basement is sticking out of the soil. so I would prefer to fill those cavities with the Roxul. Also, remove that old pink stuff. Anyway, it's not that effective like roxul. Roxul is mold free, waterproof, Air barrier and also fireproof.

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Shannon
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Re: Insulating split level basement

Post by Shannon » Wed Sep 19, 2018 3:24 pm

Roxul is not an air barrier.
In this case if the owner is also insulation the inner framing the old batt insulation is fine to stay.
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SarahS
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Re: Insulating split level basement

Post by SarahS » Thu Sep 27, 2018 9:26 pm

Thanks!
Quick question: We have started sealing up the vapour barrier with accoustical sealant (with help from your video!) I’m noticing a strong smell from the accoustical. Does this go away with time even if it’s a non-drying product?
Thanks!

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Shannon
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Re: Insulating split level basement

Post by Shannon » Thu Sep 27, 2018 10:00 pm

I have never really noticed a smell from that product , but I have maybe been a round it so much I don’t notice. I would think it should dissipate
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