# Frame out basement half wall



## diyinwi (Mar 18, 2012)

Hello,
I have a Wisconsin daylight basement that I am looking to finish off. My basement wall consists of a concrete wall that is 44" high with the remaining wall studded and insulated to the floor joists. I intend to insulate the face of the concrete wall with 2" XPS and then build out a 2x4 half wall in front of the insulation. As you can see in the photos I attached, the top of the concrete wall extends 3" beyond the existing studs. Also, I have numerous windows in my basement in which the bottom of the sills are 3" above the concrete wall. I would like the finished product to be drywalled and the top of the half wall to have a nice wood cap. Cap would need to be a minimum of 8.5" (3" exposed concrete+2"XPS+3.5" stud wall).

My questions to anyone with experience are?
1. How high should the 2x4 half wall be considering the 3" distance from the top of the concrete to the bottom of my window sills?
2. How thick can the insulation be on top of the concrete wall (I was thinking of using 1"-1.5" XPS on top)?
3. If I want a wood cap, do I need drywall beneath the cap?
4. What is the recommended method for attaching a cap?


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## Mohonri (Apr 2, 2012)

Our basement has exactly the same issues (and I have a lot of the same questions!)--for me, I'm actually planning to build the wall straight up--that way, I don't have to worry about how to secure the top of the half wall. For insulation, I'll do either fiberglass in the bottom half of the stud bays, or fiberglass all the way up, with more fiberglass just to fill in the void between new wall and exterior framed wall. That's all subject to change, though...

As for determining the height of the half-wall, the best way IMO is to work backwards--measure the height of the existing sill, subtract out the thickness of the cap and anything else that would go between the top of the framing and the cap. I would think that you'd be able to nail/glue/screw the cap right to the top of the half-wall. In that case, the drywall would not be serving any purpose, really. That approach would also give you a maximum thickness of XPS on top of the exposed concrete.

Any experts have some good advice for this one?


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## joecaption (Nov 30, 2011)

Why cap the wall? I'd just build a wall and add jamb extentions.


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## Gary in WA (Mar 11, 2009)

You may have a problem getting the code required 44" *to the window opening*...... Use thickest foam possible- on cap, as said: 
http://www.buildingscience.com/docu...merica-high-r-foundations-case-study-analysis

Gary

P.S. - Welcome to the forums!


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## mae-ling (Dec 9, 2011)

You could frame out around the window to be flush with your wall below. This would leave a shelf for the rest of the wall if you want and alllow maximum foam insulation below the window.


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## Mohonri (Apr 2, 2012)

GBR in WA said:


> You may have a problem getting the code required 44" *to the window opening*...... Use thickest foam possible- on cap, as said:
> http://www.buildingscience.com/docu...merica-high-r-foundations-case-study-analysis


I actually think the code requires the 44" to be to the window *sill*, but I could be wrong.


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## Gary in WA (Mar 11, 2009)

I'll explain to you the way it was explained to me by an AHJ a dozen years ago.LOL...

"
*SECTION R310 EMERGENCY ESCAPE AND RESCUE OPENINGS* 

*R310.1 Emergency escape and rescue required.* _Basements,_ habitable attics and every sleeping room shall have at least one operable emergency escape and rescue opening. Where _basements_ contain one or more sleeping rooms, emergency egress and rescue  openings shall be required in each sleeping room. Where emergency escape and rescue openings are provided they shall have a sill height of not more than 44 inches (1118 mm) above the floor. Where a door opening having a threshold below the adjacent ground elevation serves as an emergency escape and rescue opening and is provided with a bulkhead enclosure, the bulkhead enclosure shall comply with Section R310.3. The net clear opening dimensions required by this section shall be obtained by the normal operation of the emergency escape and rescue opening from the inside. Emergency escape and rescue openings with a finished sill height below the adjacent ground elevation shall be provided with a window well in accordance with Section R310.2. Emergency escape and rescue openings shall open directly into a public way, or to a _yard_ or court that opens to a public way. 

*Exception:* _Basements_ used only to house mechanical _equipment_ and not exceeding total floor area of 200 square feet (18.58 m2). 

*R310.1.1 Minimum opening area.* All emergency escape and rescue openings shall have a minimum net clear opening of 5.7 square feet (0.530 m2). 

*Exception:* _Grade_ floor openings shall have a minimum net clear opening of 5 square feet (0.465 m2). *R310.1.2 Minimum opening height.* The minimum net clear opening height shall be 24 inches (610 mm). *R310.1.3 Minimum opening width.* The minimum net clear opening width shall be 20 inches (508 mm). *R310.1.4 Operational constraints.* Emergency escape and rescue openings shall be operational from the inside of the room without the use of keys, tools or special knowledge." From: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_3_sec010.htm


Notice it says "openings" rather than window sill. If it wasn't measured to the *opening*- some could install a window much higher and the wall framing trim sill much lower to meet code. But the fireman with his oxygen tank on-- would fall because the inside floor wasn't as per code but lower. The sill of a window unit is the bottom horizontal frame directly under the opening part of the window- slider or casement, etc. "Opening shall have a sill height of...." Underline is mine. Sill of the window unit, not sill of the wall frame.

Gary


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