How to Fix Sloping, Out of Level Floor?
Q: My floor slopes and is out of level. One end is noticeably higher than the other end. Peas roll off the plate! How can I fix it? Can I use levelling compound or is something more “serious” required…and I do not look forward to your answer because I’m afraid what it will be.
–Karin B., Toronto, CN
A: It’s one thing to have a floor with occasional depressions and gaps; it’s another thing when the entire floor slopes in one direction or the other.
You have to ask yourself: Is this a flooring problem or a structural problem? Because when the slope is pronounced–indeed, when we use the word slope at all–it’s no longer a flooring problem. It’s a problem with joists, structure, foundation. All that big, hairy, scary stuff. So what to do?
Flooring Slopes to the Center – Sagging Floor
If you’ve got a floor that slopes inward–from the perimeter to the center of the room–you’ve got sagging joists. Your fix goes beyond using leveling compound. You’ll need to strengthen the floor joists and even add beams and piers underneath–can you handle it? Depends on how hardy you are; most homeowners will call in a contractor at this point.
Or if you can determine that the joists are structurally sound (i.e., not quickly rotting away), you can “sister” the joists, which does two things:
- Strengthens the joist.
- Provides a new, level surface for your subfloor–you’re essentially circumventing the whole “slope” factor and running level boards next to the sloped ones.
Good thing: it works. Bad thing: it entails ripping up the entire floor–finish flooring and subfloor alike.
One End Slopes to the Other End – Foundation Subsiding
It’s a larger problem when one end of the floor is higher than the other end. This means a subsiding foundation, and bigger construction work. You will need to call in a contractor–not necessarily a foundation company, but just a competant contractor–and jack up the lower end of the house, insert beams, and lower the house. Simple, huh?
If the floor isn’t too far out of level, you might be able to insert tapered wood shims atop the joists and re-install the floor. By “not too far out of level,” I mean something like half an inch vertical per ten feet, roughly. Again, you’re ripping up the entire floor (bad thing) and once your fix is completed, you have other problems to deal with, such as:
- Installing new baseboards and trim to accommodate this out-of-square room.
- A noticeably different look to the room. For instance, windows on the “corrected” side with be closer to the baseboards than on the other side. The human eye can pick up these differences.