Joist Repair

SuperPlumber

Hi Experts,

Ive just been to diagnose a leak at a friends house and in the process of removing the plasterboard ceiling below the shower, the 2 joists below the leak are damaged.

One has been exposed to water for quite some time and is almost rotted through although is still intact, you can push a screwdriver into the damp wood to a depth of about an inch

another has been affected only on one side, but to a lesser extent.
Both joists run parallel to the nearest outside wall and the rot extends only 20cm either side of where it has been exposed to water


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outside wall
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joist 1
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joist 2
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is it possible to brace the joist?

Ive had a look at a few threads which suggests "sistering" the joist but should he cut away the rotten area after sistering to prevent further rot and insert a block into the gap?

Can anyone share an insight into the process of repairing joists...assuming that the ones in question dont need replacing.

Thanks

MM

Termite

If they're softened due to water damage they do need to be replaced. I would suggest removing the punky wood if it is still wet or if there is mold on it. Taking the whole joist might be necessary. It is of very little structural value. If it is dried out and you've taken care of the moisture problem I would leave it.

Sistering another joist in is probably the best option. It needs to be full length, which will involve pulling back any electrical or plumbing that runs through it...No notching in the center 1/3 of the span! Assuming the old one is dried out you can leave it and attach directly to it. Spacer blocks between the joists are ok too. Just be sure not to splice it or not provide adequate bearing at both ends.

If it is just a 2' or less portion of the joist that is damaged, you can always cut out the bad spot and header it off to the adjacent two joists.

SuperPlumber

Thanks for the quick reply,

I think that structurally its one of the least load bearing so removal would be overkill, but your advice on sistering and maybe even headering off would be acceptable. Since its the ist joist in the run, how would you header off against the adjacent joist as theres only one to its left and the wall to its right.

This is probably a belt and braces approach but any further feedback would be appreciated.

Thanks again for sharing your opinion and i hope it may be of value to any other diyers via "google"...its the reason i decided to ask for assistance as i couldnt find anything more specific on the web

SP

Termite

So this is adjacent to the foundation wall? If so, you can certainly bear the header on a piece of material bearing on the foundation wall, or sneak it up on the mudsill if you can.

Cut out the rotten part and use pieces of lumber of the same dimension (2x10 or whatever the joist is) perpindicular to the joists. I'd suggest using joist hangers on the header pieces' connections to the joist, and also at the connection of the tailjoist to the header.

Just remember that the 3/4" floor sheathing cannot span more than 24" in any direction...So a 24x24" area would be the biggest area you can have that is not supported by a joist. Hope that makes sense.