Furtling under the floor in the bathroom for other reasons, I found
water has been running down the side of the bath (from the shower over
it) and saturated a confined area of a floorboard, together with the
joist below. Now that I've resolved the source of the water, I'm
wondering what's best to do about the joist.
It's a 3x6, spanning 3m, fitted into sockets in the brickwork. It's not
currently bouncy or anything, but it does suport the side of the bath.
Replacing it would be a PITA but if I'm going to have to, I need to do
it soon, as I'm currently working on the room beneath and it supports
the (L&P) ceiling.
The wood is 'spongy' for the top 30/40mm just before it goes into the
socket. I'm thinking that when it's had a chance to dry I may be able
to hack out the soft bit, treat the remainder with wood hardener then
let a bit of fresh timber in to restore the dmensions (to level it for
floorboards and stop if rising in the socket).
Does this sound like an adequate repair or is there a better way to deal
with it? Any sensible advice would be appreciated.
I had thought of something like that, if necessary, but I haven't seen a
hanger that would let me get a new joist close up against an existing
one. Maybe it would work with a spacer at each fixing though.
I'd been trying to think of how that would work, as it's a 3inch joist
already, so I'd need a 5 - 6 inch hanger (if they exist?) plus to go
around the bottom it would mean I would have to cut away some of the L&P
ceiling. Currently, I'm hoping that the damage isn't too deep so the
bearing end is still up to the job. Then I can just let a new piece in
or pack the space with something, once I've removed the soft stuff.
You can get wide ones, although I will admit I had forgotten about the
Having said that you could chop away a small bit of the underside of the
joist near the wall without disturbing the ceiling attached to it if you
needed to make a path for a shoe etc.
Yup, there are plenty of options usually. Slate often makes a good
packer (crush resistant and also acts as a DPC).
I would be tempted to fill the bath with a known quantity of water, and
measure the joist deflection and compare with the "good" joist.
The idea of taking down a L&P ceiling would horrify me. Its a very messy
process! Were you going to take it down anyway, in which I would follow
Colin's advice and place a good known joist along-side using joist hangars.
Having said that, most joist hangers I've seen aren't conducive to
sliding a joist into the hanger, so that might be more difficult that
it first seems.
If the sponginess is less than a third of the depth of the joist and close
to the wall, then once you have eradicated the damp problem and the joist
has tried out you should be okay.
If you still feel unsure, just fish-plate a couple of lengths of 6x2 about
6 - 8 foot long either side (or only one side if cost and access is a
problem) using bolts and metal joist connectors. Drill the bolt holes in the
centres of the joists to retain maximum strength.
With regards to the 3" joist, is that supporting a stairway or other access,
or is the span between supporting wall excessive - as 3" joists are usually
used as Trimmer and Trimmed joists to carry the extra loads at openings?
Further to that, it would be a good idea to apply timber preservative when
it's dried out just in case some dry rot has got a toe hold.
However if the wood is rotten there will be nothing to fix your floorboards
Nothing stopping you cutting out rotten wood & splicing a bit in so long as
it goes right into the wall and using PVA glue and nails/screws.
I'm sort of hoping that should be the case, but wanted to see if anyone
would tell me otherwise. Although it would be a pain to swap it out,
I'd rather do it while the room beneath is gutted if I have to.
Since this is very close to the end of the joist, I'm not sure
reinforcement along the length is really the issue. I'm more concerned
about the bearing end of the timber. It seems to have retained its
strength but softness at the top could, in principle, allow it to
deflect more and it could weaken in time. I think it needs hardener at
least and a good treatment for rot and insects wouldn't hurt, but I
suspect it will need building up/packing out to make up for any very
soft material I have to take out.
It's not a trimmer or anything: All the joists in this bathroom are 3 x
6 by 10ft. It's been there a long time (100 yr +), so I guess they just
used them to give a bit more strength for the depth. Not that it seems
to gain much, judging by modern span tables.
On Tuesday, February 24, 2015 at 7:54:47 PM UTC, Roger Mills wrote:
That's a build regs table, which is far removed from what's sufficient. BR oversizes joists massively in an attempt to reduce noise transmission. In Victorian times thick plaster was used to do that instead.
IMHO it really depends on whether it might be dry rot. Having learned
the hard way from an instance which didn't have a clear dry rot
signature, but turned out to be.
"Dry rot" can cause a lot of unnecessary panic. But the real thing can
Chopping out the soggy bits and replacing with new timber will restore
the correct height for supporting the floorboards, and will make it fit
the socket properly - but will do nothing to restore the joist's bending
stiffness. As others have suggested, this may not matter - but if you
are worried about this, I would suggest bolting some metal plates -
maybe 3' long x 5" high x 1/4 thick to the sides of the joist at the
'soggy' end to reinforce it.
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