Return to the Basements Forum | Post a Follow-Up

 o
Uneven basement floor

Posted by javastu1 (My Page) on
Mon, Jun 30, 08 at 0:14

I am framing a basement in 2x3 studs using pressure treated lumber for the bottom plate, which I intend to drive into the floor with a Ramset gun. This is my first framing project and I have already run into a problem. The concrete floor of the basement slopes slightly downwards as it moves away from the concrete walls. This makes the bottom plate slope as well. What to do?

The only thing I can think of is to measure the angle of slope and use a table saw to shave of the appropriate angle off of bottom of the plate so it'll sit flat on the basement floor. It sounds like there should be an easier way.

Can I shim the bottom plate - raising one end so that it lays flat? Do the shims have to be pressure treated as well?


Follow-Up Postings:

 o
RE: Uneven basement floor

I've finished a lot of basements new and old and haven't come across that. It must be some steep slope that it's noticeable 4" from the walls! I'd place the base plates on 1" strips of XPS and not bother with p.t. Then shim o.c. where you intend to frame the uprights.


 o
RE: Uneven basement floor

It is an old house and basement floor is quite regular except that it slopes slightly as it meets the walls. I have measured the angle and it is a mere 2 degrees. It doesn't look noticeable to the eye, but when you stick a vertical stud on a two degree slope it sticks out rather than go straight up to the top plate!

Doing a little trigonometry will tell you that for a 2 degree slope a 7 foot stud will miss the top plate by around 3 inches!

Shimming for every stud sounds like more work than need be.

After talking with some folks, I think I am going to set my table saw on a 2 degree angle and shave a little off so it lays flat.


 o
RE: Uneven basement floor

Use 2 x 4s. For the increase in price, it is better lumber, straighter, fits more insulation,etc.


 o
RE: Uneven basement floor

Use 2 x 4s

I didn't even notice that! I agree.


 o
RE: Uneven basement floor

Well, a number of people have given me similar advice about using 2x4's because it accommodates more insulation. But hear me out...

Not only does the floor slope up slightly toward the wall, but there isn't a clean edge where the wall meetings the floor. It is not cinder block but poured concrete and the walls/floors have a very rough finish to them.

So no matter what size I use for the bottom plate, I cannot place the bottom plate snugly up against the wall. So using 2x3's I will still effectively have a depth of a 2x4 and possibly slightly more.

So will you guys now change your minds?


 o
RE: Uneven basement floor

That raises another issue. Framing up tight against the concrete walls, then filling the space between the studs with fibrous insulation is a discredited, if still popular, way of insulating a basement. XPS, EPS or foam on the walls is the way to go. Then you can add whatever you want between the studs. But that's another whole topic....


 o
RE: Uneven basement floor

Your bottom plate does not need to fit snuggly against the wall. If you are out of plumb, just move your wall out a bit from the wall so you can compensate and have a straight wall from the top to bottom. Set you top 2x4 and drop a plumb bob down to set the edge of your bottom plate.


 o
RE: Uneven basement floor

How about beveling the bottom plate so that it will sit up against the wall. Let it set at whatever angle it wants to then cut the bottom of your studs to match so that they will go straight up. Have you checked the wall for plumb? You may have to move one of the plates out to get a plumb wall.


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Basements Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here