correct framing for knee wall

FileOpen · 10-05-2012, 12:23 PM

Are there "by the book" rules for building a knee wall??

I have a 60 year old house. I'm slowly making progress on re-finishing my attic. The original walls were made from 3/4" thick wood panels. There were horizontal furring strips along the knee walls and rafters to support the panels. I removed all the furring strips so I can reinsulate. The 3.5 foot high knee walls were made by toenailing 2x4 studs directly to the floor and nailing them to the rafters. I expect that there would usually be a 2x4 nailed along the floor and then studs nailed to it and the rafters.

Since I plan on using sheetrock for the new walls, it would be nice to have some horizontal support. Should I cut 2x4s to fit between the knee wall studs at the top/bottom??

Or just rebuild the knee walls from scratch (which I hope would be less time consuming)?? What is the correct way to build the knee wall for my situation ??

Thanks for your attention.

woodworkbykirk · 10-05-2012, 05:08 PM

build it in place and use a top and bottom place. not only will it keep the wall straight by snapping a chalk line on the floor and underside of rafters but the plate will also keep the sheetrock from flexing between studs

joecaption · 10-05-2012, 05:19 PM

It's also far less work if the wall is 4' not 3', that way you can use whole sheets with no waste.
A 3' wall is about use less anyway.
With some planing you can use some of that space behind the wall for storage for seasonal item by adding a floor, walls and a door.
Your going to have to add foam baffles for air flow to the ridge from the soffit vents. If you have 2 X 6 or less rafters it's best to add shims so there a total of 8" to fit insulation and the baffles.

FileOpen · 10-05-2012, 05:29 PM

Quote:

Originally Posted by joecaption

It's also far less work if the wall is 4' not 3', that way you can use whole sheets with no waste.
A 3' wall is about use less anyway.
With some planing you can use some of that space behind the wall for storage for seasonal item by adding a floor, walls and a door.

How do I handle the top plate of the knee wall where it meets the rafter ? Does the top plate have to account for the slope or the rafter? Or do I just nail it and handle the gap with sheetrock ??

Thanks

joecaption · 10-05-2012, 05:45 PM

Like this will work, the top 2 X 4 will keep the wall from being wavy.
http://www.bing.com/images/search?q=...48146F&first=1

It's very important to snap a straight line and use the longest lumber possible or that top seam will stick out like a sore thumb.
I use the paper tape with the metal backing when finishing it.
If you google "framing a knee wall" it will come up with pictures on how to frame in a door.

mae-ling · 10-05-2012, 08:01 PM

YOu can rip your 2x4 (or use a 2x6) to the angle for the top plate but it really is not needed, the slight gap at the top will not matter, just screw below it.

woodworkbykirk · 10-05-2012, 08:15 PM

mae ling is right. having a 2" gap at the top wont matter..

2" because the angle creates a longer line than 1 1/2" for the thickness of material

FileOpen · 12-15-2012, 08:23 PM

Late following up... when nailing the top plate of the wall, I should nail through the top plate into the stud, correct ?? Meaning when the wall is standing, the nails in the top plate are pointing down, correct?? It's very difficult to nail the stud to the top plate, so that would be the wrong thing to do.

Also, I've seen some pictures where the studs for the knee wall are not directly lined up with the rafters so the top plate can be nailed to the rafter. I guess this is the norm ??

Thanks !!!