In my son's bedroom there is a raised spot in the floor along one of the joists. I went into the crawlspace with a level and that joist is bowed up about 3/4" to 1" compared to the other joists on either side of it.

Best I can tell, this may have been like this when the subfloor went down as the subfloor is well attached to the joists in this area. Also, the blocking isn't flush with the bottom of the crowned joist where it peaks. Everything else around this one joist looks okay and I'm not noticing any signs of settling in the drywall inside or the brick outside.

I noticed the raised spot shortly after we bought the house a few years ago, but recent furniture placement has made it incredibly obvious. I don't think it has gotten any worse since then. Is there anything else I need to look for that might indicate a serious problem?

If the problem is just this one joist being bowed up as I suspect, what are my options to remedy the situation? Is there any way that I can pull it down from below?


After thinking about this some, would it be possible to attach a piece of steel angle or t bar to the crowned joist with lag bolts and use the joists on either side to pull it down?

  • My first thought: assuming you can get at the joist from underneath, first draw a level line at the top of the joist. What's above this line is the part to be removed. Then use a reciprocating saw to cut out this part. I would use a metal cutting blade because you'll likely cut through nails too. Next, if necessary to re-anchor the sub-floor (in your judgement), I would drill pilot holes through the joist at angles. Then, with someone standing on the floor to push it down onto the joist, attach the joist to the sub-floor with decking screws.
    – getterdun
    Feb 2, 2014 at 6:19
  • how long is the bowed floor joist? You are certain this is the only joist with the problem? Feb 2, 2014 at 13:10
  • @shirlockhomes The joist is bowed for most of it's length. It tapers from peak over about 4' on either side. This joist is the next to last one from the outside wall. The joists on either side plus the next two towards the middle of the house line up.
    – Josh Bush
    Feb 2, 2014 at 15:42
  • @getterdun The length of the crown is pretty long. I think I would need to do this from above to make a decent cut.
    – Josh Bush
    Feb 2, 2014 at 15:44

2 Answers 2


Pretty simple to fix if you have access from underneath. I would start by adding a couple of 2x4 with screws underneath several of the joists on each side of the problem joist.

Next, cut the joist vertically at the location where the bump is. This will let the joist sag down on top of the 2x4 braces that you added.

Finally add a sister next to the joist that you cut. The simplest thing to do is to use a piece of wood of equivalent size as the existing joist. It is glued onto the existing joist with construction adhesive and then bolted together securely with closely-spaced bolts.

  • +1 Good idea, I wished I thought of it. Actually the 2X4s could be added after the notch is made and the glue and 8 ft. long joist is applied. Then use screws to draw down the crown, then set the splicing joist in tight. The joists that is cut, will stay crowned unless acted upon by an outside force, though it may drop a teensy bit... not enough for concern. With a little forethought it can be assembled in such a way that one 2X4 is placed loosely to make it easy to slide the splice in place before the other 2X4s are added.
    – Jack
    Feb 3, 2014 at 13:28
  • How long should the sister be?
    – Josh Bush
    Feb 3, 2014 at 15:40
  • @ josh, 8 ft long with construction adhesive and 2 1/2 or 3 inch screws
    – Jack
    Feb 3, 2014 at 22:13

I was thinking along the line of the steel angle too, but do it in at least 2 places if not 3, where they are spaced 2 to 4 ft. apart depending on how long the span, the idea would be to break it up in thirds, the mid third is where the steel would be, then split that up into equal spaces for the placement of the angles or Kendorf track is what I was going to suggest. Not lag bolts either, they will pull through with enough force drawn on them. My idea was to use a tightly bent 1/2" all thread, or a long 1/2" bolts the correct length, with the head welded to the head of another 1/2"bolt the right length to go through the joist a few inches below the top of the joist. The short bolt is drilled through the joist and set with washers and a nut snugly, and the long bolt is ran through the metal that is under the joist and set with a washer and nut too. Tighten down in stages, the joist will not want to go straight in one setting. It will take 2 or 3 tightening to get it straight, with a week or longer between each tightening. Alternate the placement of the bolts so all are not pulling to the same side, trying to twist the joist.

  • 1
    In my opinion the joist should be cut down from the top, I had to do that in my home, it takes a couple of hours once the flooring is gone, of course, that is the trouble, the flooring. Mine was easy I had new carpet coming in the next day. I noticed the high joist when I removed the old carpet. I cut out a span of plywood over 3 joists total, the high one in the center, planed it down with my electric planer and was able to reset the same subfloor I cut out. I pulled all the nails first then cut the path the nails were on with a saw set to depth of the subfloor.
    – Jack
    Feb 2, 2014 at 21:01

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