# Proper way to insulate split level basement?



## Nealtw (Jun 22, 2017)

Normally we would put a wall from the floor to about 8" above the concrete and use a 2x8 or 10 for the top plate. We build a 2x4 wall 1" away from the concrete and insulate that with bats and vapour barrier. 
But you could do the same thing full height or put foam up first. 
You could do foam and a 2x2 wall up to the top of concrete and a 2x4 wall above that.
You could use that space behind for hiding the dart board or TV??
What ever you do you want solid fire stop between the top of the wall and the floor system.


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## GarrettG (Sep 22, 2018)

The height where it dips back is right in the middle of where monitor height would be while sitting at a desk, so goal is to have the wall go full height, even if I have to take 6-8" out of the room to accomplish it. With that in mind, my goal is to fill out the gap in a way that won't promote moisture(or fire). I am not hugely concerned with material cost(paying to have spray foam done might be pushing it, but a couple thousand in insulation is okay if required). 

Just not sure what material would be best to fill the gap and whether I need to do anything with the existing vapor barrier/wall/batts. Basement has been dry so far, but don't want to trap moisture behind the XPS and end up with mold growing unseen in the existing pony wall/batts.

Thank you for the tips.


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## Nealtw (Jun 22, 2017)

You could just move the VB to just behind the drywall and fill the space with more bats.
That would give you a better thermal break from the studs.


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## Bud9051 (Nov 11, 2015)

Your approximate location, closest big city works, so we can judge the temperature range you will experience. 

As an example of what you need to consider, many houses will add a one inch layer of rigid insulation to the outside before adding new siding. In a cold climate the inside surface of that rigid can drop below the dew point and condense the moisture from the inside air. There is guidance for how thick that outside rigid needs to be in relation to how much other insulation is installed on the inside. Thus, adding 2" of rigid and then filling everything else with fiber insulation might be a problem.

Give us a location and I'll dig out that link.

Bud

And welcome to the forum.


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## GarrettG (Sep 22, 2018)

I'm in zone 5A, outside of Storrs CT. I am not sure if there is any insulation installed under the siding, the house was built in 1997 and has not undergone a remodel. If there's a way to check that isn't particularly destructive, I can go take a look.

All of the help is much appreciated, a lot more seems to go into properly insulating a basement than I thought at first glance. I want to do it right the first time to ensure I don't have problems down the road, especially since I intend to keep a lot of electronics in the room.


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## user_12345a (Nov 23, 2014)

Where the above grade wall is that's a few inches out, could you only put foam on the concrete foundation and leave the above ground as is? Now it's fiberglass with vapour barrier which is okay for above ground.

There would be a gap between the framed wall and the exposed exterior wall, but this won't pose a problem as long as the insulation and barrier there are left intact as is.

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For the normal foundation, it's best to just use 100% foam and not put any batts due to risk of condensation as Bud brought up.


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## GarrettG (Sep 22, 2018)

Would there be any concern of fire channels or code violation if leaving the gap between the existing vapor barrier and the new framed wall? That would certainly make the job a lot easier/more affordable.


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