I am framing some non-load bearing walls in my basement. Due to a stupid mistake, I just completed an 8′ section that is 1/4″ to 1/2″ too short. I’m building the segments on the floor, raising them and attaching the top plate to a second 2×4 already attached perpendicular to the joists. Can I just shim this gap? Or is this too much of a gap to meet code?
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That is perfectly fine. It is actually a lot easier to frame basement walls like you just did, 1/4 to 1/2 inch short and shim between a second top plate already attached to bottom of joists (for non load-bearing walls). Concrete floors are not always perfectly level and flat.. so a little play in the wall height helps to deal with that.
I plan on taking this approach but maybe mixing with the "build in place", too. If you pre-build the wall it's almost impossible NOT to have to shim it like you plan on doing. Some say building in place (one stud at a time with bottom and top plates already there) is easier but shims aren't the end of the world.
You are in great shape and in fact if your house is still fairly new and settling the gap may be necessary to prevent problems in the future as the foundation settles and the slab continues to float a little higher on the soil.
New construction in some areas of Colorado's front range had 2" of gap in the basement framing to allow for this--it looked crazy, but those houses settled a great deal since they were built on flat farm land recontured by the developers into lakes and small hills.
That requires using pins or l clips or something, though, to deliberately allow the walls to float. His approach with shims will still have the walls locked to the rest of the house, so if the slab stays put and the foundation walls sink at all he's got himself new load bearing walls. That is what most people end up doing.
I actually posted about this elsewhere today. Unless local code specifically calls for this approach of floating basement walls for the problem you mentioned (and honestly ALL references I see are in regard to Colorado for this; is it code elsewhere?), is it worth building in elsewhere? It certainly ads to the task. I wonder if most people need to worry about it...?
At least one of the Kansas City suburbs in Kansas requires it because of expansive soils. But not nearly as bad as in CO.
I think maybe 1/2 - 1", but not sure.
I think that they just use a long spike. It has been a long while since I have seen the drawing. But I think that they are at the bottom, not the top, so that baseboard hids the moving seam.
For a 1/2" gap there are some ready made verticle pins that can be easily installed to allow the wall to float: normal 16d gun nails shot verticlally. Two nails every 16" will still move just fine in most cases if the house starts to settle more than the slab.
Every house will settle a slight amount when first built--I am so curious about this that I keep swearing to put a convinent elevation pin next to a project and monitor it throughout the process and into the first full year---that's hard to do -- at least it gets pushed to the back burner and forgotten on my projects.
I'll bet it's more common for interior fill to be poorly compacted prior to concrete placement for the slab and if anything the slab falls more than the footer settles in.
When I'm looking at an older house, older posts often have a separate footer cast under the slab--at times it's easy to see if the slab has fallen or risen relative to the post--hard to tell which has stayed put, but often a shallow footer on the exterior walls results in interior posts that are higher than the exterior walls over time.
A water level is a great way to run a perfectly level refference line (+-1/32") around a crawlspace or basement to see how level a house really is.
It's facinating how houses age! :)
I've seen that framing in
I've seen that framing in basements. At first glance it looked weird.
Perfect reason to use metal tracks and studs. You can cut a whole bunch of studs just short and it don't matter.
Also if you don't want the
Also if you don't want the wall to be ever loading bearing the metal studs are much weaker so would be less likely to heave anything. I asked my inspector today about a floating wall and he had never heard of it in this area. It does appear to be quite a limited-scope consideration, really. I plan on going all wood and snugging them up top and bottom. If metal was cheaper right now (studs are $2/piece, I think metal is more than twice the cost) I'd try it.
A town over I've a friend who just got his permit from a pretty pedantic town and they don't mention this need, either.