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Basement Insulation

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Posted by: from Warman
1/14/2019 at 3:35:34 PM

We are planning on slowly framing our basement and have a few questions. We have chosen fiberglass insulation over sprayfoam(cost). We also have waterproofed concrete basement walls(black tar). Do I need a moisture barrier between the insulation and waterproofed walls? If not, how do I keep the insulation from touching the wall? Do I need the half inch airgap between framing and concrete? What r-value should my insulation be in canada for basement walls?

REPLIES (6)
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Date/Time1/14/2019 at 5:37:19 PM

You say you have waterproofed the basement walls; probably what you mean is dampproofing (waterproofing is something different where you have high groundwater) and you haven't said whether it is on both inside and outside. Good idea to provide interior dampproofing - Code requires that it terminate at grade level same as exterior dampproofing.

Not a Code requirement to have a 1/2" air gap but it is highly recommended.

New Energy Codes require minimum R-20 for the entire assembly including studs. Vapor barrier goes on the warm side of the insulation. Suggest you confirm all information with your municipality as permits should be required.

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Auryn in Warman
Date/Time1/14/2019 at 5:53:58 PM

Sorry...should have been more clear. Yes the black waterproofing/damproofing is on both sides of the basemeny walls. Our house is only 4 yrs old and all houses in the area have the same treatment. There is no 'local' building codes where I am, the city just follows the national program

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Date/Time1/14/2019 at 8:32:56 PM

I see that Saskatchewan simply adopts the National Building Code without provincial changes - same rules apply as previously mentioned.

Certain minor projects may be undertaken without permits however your project could require development, building, electrical & possibly plumbing & HVAC permits depending on what all you're doing.

When applying for permits you can seek advice/clarification from the plans examiners to confirm requirements.

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Date/Time1/14/2019 at 9:27:18 PM

Hi,

I would glue R-10 blue foam insulation sheets to the foundation walls. As well as cut sheets that fit in the wood structural sections between the floor joists.Tuck tape all the seams very well. This now gives you R-10 plus a vapor barrier. Then frame all the inside walls leaving space for R-20 insulation installation. Leaving the half inch space between the solid foam and the insulation in the framing.

You now have R30. And a proper moisture barrier.

Hope this helps.

Regards,

James Fram

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Date/Time1/14/2019 at 10:24:25 PM

You need a 1 inch air space between the back side of your studded wood wall to the concrete wall. You need to put the 6 mil vapor barrier on the warm side of the wall before you install drywall. R12 is minimum insulation which is for a 2 x 4 wall however I recommend a 2 x 6 wall with R20 insulation. If you can afford it it is Walworth spray foaming it with a two-pound sprayfoam this has a 6 mil Vapor Barrier built in and saves you time and money for that part of the process as well as using a two-by-four wall with maximizing your insulation value. Happy renovating. Jeff

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Date/Time1/16/2019 at 7:57:37 AM

Hi

Fiberglass insulation not the best option, it's a ? of pay now or pay later (mold).

To answer you ? moisture barrier not req. if a 1/2 to 1" gap is left,this also helps get walls straight, lets water vapor get out through the rim joist,poly is never 100%. Next problem minimum code in most places is now R20 so 2x4 walls don't cut it.

Your best option is frame 1" off the wall and use 2 lb.foam. Or use 1 1/2" minimum or 2" ridged foam (perm rating .7 to.5, excepted under code as a barrier in most locals), glued to wall, frame no gap and use your fiberglass insulation to finish (NO!!! 6mm plastic) the foam is your vapor control.

Hope this helps

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