Took floor boards up in kitchen as they had woodworm. Didn't think it was in the joists, but theres a couple with some in. It only affects one end of them, from the wall to around 750mm out.
So, I want to sort it before I re-lay the floor.
The joists are butted into an external wall (with cavity) at one end, sleeper wall in the middle then an internal load bearing (rear side of chimney breast) wall at the other end. They're around 3300mm span.
I'm thinking I've got two basic options...
1. Replace the complete joists, the only issue here is that I'm not sure about how I get the new one in? Would there be enough room within the wall to slide one end in, then the other? I assume the cavity in the exterior wall would provide the clearance needed to be able the push the joist far enough in to then get the other end in?
2. Replace the damaged ends only. If I went for this, I'd cut the existing joists, butt up a new piece and then lay a length next to the join, bolt through using dog tooth washers between the two.
Couple of questions for this option though, should I cut just past the damaged part or make the join over the sleeper wall? What length of timber should I run along next to the join? At what centres should I bolt through?
Oh, and I'll be treating the remaining joists with Boron powder as recommended in my previous woodworm thread!
If you can cut back to the sleeper wall then strength at the joint is pretty irrelevant, just depends whats easiest. I often just remove 400-800mm or so back to sound timber and do what your suggesting. I tend to glue with polyurethane rather than use bolts as I find it quicker and there is nothing to come loose as things shrink. You can put cheeks on both sides easily as well.
Length of brace is depends on how close to the ends your joint is, longer the better really. I think this is where bonding comes into its own as there is no joint creep or movement. Use a bottle jack to get everything up where you want it before making the joint.
I'll have another look and see how easy it'll be to saw the existing one over the sleeper wall, think I probably will make the joint over there if I can as it'll make lining up the joint a lot easier as the sleeper wall will naturally hold the joint at the right height...
We've just had this exact thing done. Ours were a mix of joists butted into the wall and joist hangars on a wood frame round the room.
The ones butted into the wall were cut ~1m further back from the end of the damage and then another joist bolted on the side and butted back into the wall. The hole in our wall was big enough for this, YMMV. The major thing if doing this is to paint the end of timber with rot treatment and wrap it in some heavy duty DPC before positioning it in the wall.
The ones on the joist hangers were much simpler. Same basic thing with cutting away the damaged bit + some extra, bolting new joist onto side and positioning this on a new joist hanger.
For us, it was just 4 bolts over the length of overlapping wood. 2 in the top half, two in the bottom. Doesn't hurt to lather it in glue as well. Oh, and use some big square washers on the outside to stop the bolt head/nut crunching into the wood.
I think overall it would have been better to replace the joists in full, but the cost and time involved were not conducive to a happy household so we repaired instead.
I think overall it would have been better to replace the joists in full, but the cost and time involved were not conducive to a happy household so we repaired instead.
Yep, I think it'd be better to replace the whole thing too, I'm just not sure how I'm supposed to slot the new one into place?!?
At least in our house, there was enough depth in one side to slide the joist in that way at an angle, then drop to horizontal and slide back into the other side. The amount of joist you need to have supported on the wall is surprisingly small.
If you want to replace the whole joist, just cut the new one in two and overlap them on the sleeper wall and fix back together, as said before, the sleeper wall is taking the main loading.
Great, I've got a plan then. Ill saw the existing joist on the sleeper to remove it, that'll let me figure out if there's enough depth in the wall to get a new one iin there, if not I've cut it in the right place to put a new section in.
Thanks for the help. 🙂
Was there some dampness from the cavity, like the end of the joist touching the outside brickwork, that contributed to your problem? I ask because I've dealt with exactly this.
Not that I saw, and the main bad areas are at the other end of the joist. I'll be treating and wrapping the new joist ends with dpc though.