Soggy joist

[GMM]

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.

[Nightjar]

I would fit a new joist, using joist hangers, alongside the old joist and bolt the two together. That will avoid the need to disturb the fixing of the ceiling, while still carrying its weight.

[Fredxxx]

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.

[Cash]

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?

Cash

[meow2222]

+1

NT

[harryagain]

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 to. 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.

[GMM]

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.

[GMM]

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.

[meow2222]

only to a trivial extent

I don't see how

doubt it

dry it & they should die

NT

[Nightjar]

I take the view that it is easier to do the best repair possible now, while the floor is up, rather than find out later that a lesser repair was not quite good enough.

[newshound]

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 be nasty.

[Roger Mills]

I guess that 3" joists were used because they are only 6" deep. Nowadays, the default for that span would be 7 x 2.

[Roger Mills]

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.

[meow2222]

2x4 is about the minimum over 10'. 3x6 were used for greater sound insulation

NT

[Roger Mills]

Not if the tables here are to be believed!

[meow2222]

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.

NT

[John Rumm]

You could get a wide shoe hanger that bolts onto the wall - then place it round the ends of both old and new joists side by side.

[Nightjar]

ITYM as well. I've lived in two Victorian houses and, in each, the joists of the first floor were 9" x 3".

[Brian Gaff]

Personally I'd not hack out the piece but treat all wood which might get wet in the future. If the damp bit is not right up against the wall, bridge the part which might be weakened in some way and screw it up so its supported.

Brian

[rowing]

Happy to advise you on our pro bono terms [

-terms-of-contract/ ] as follows: Step 1 Determine for sure the extend of the decay. If, as alleged, it is

30 to 40 mm deep and in the top that is neither here nor there and as Cash and Roger Mills say it will be OK 2 if not as little as that determine if it goes or exists in the tension bo ttom edge as that is critical 3 if not then the repairs are simply to put a block in the top (compression ) zone to carry the floor board and that is best done with a suitable gap f illing glue prior to screwing in the board above 4 Additionally, and this is key to prevent future decay, you need to rake out all the brick around the bearing using a long masonry bit and plugging chisel or whatever you can to get it all out. If necessary, cut out the si de with an angle grinder or just take out a brick. There is no other option if you want to be sure of not getting decay. (I am an expert in this field ) You need to get to the top, both sides and if possible a finger round the e nd of the whole of the bearing pocket. 5 put in a boron based preservative paste on the whole of the exposed joist end and any wall plate and masonry below. Safeguard Chemicals do suitable products but absent that just buy some boric acid and dissolve or suspend i n glycol (care!) 6 put a dpm round the timber before you brick up and when you do put also a thin slip of ply or the like in a poly bag next to the joist side when bri cking up so that once set you can remove the timber and there is a nice 1/2 " cavity for ventilation Job done! BUT if the joist has gone further and is decayed but only in the cavity and no t in the room (ie you have timber up to the face of the wall that is sound) then use a BAT Joist angle or rightangle plate to support the timber. This requires no bolting on as it is a nailed connection. Email me off line if you need more information on this. If decay is in the room you need to bolt on a new 6" x 2" timber probably a bout 600 mm long with four bolts. I disagree with going into the neutral a xis as it is a better connection half way into the compression and tension zones. You will need the classic four bolts two top two bottom and there is no need to stagger if the timber is not too wet. So that would be 100mm en d distance and 50 mm side distance in accordance with the old CP112 or its subsequent BRs Chris