Strengthening options for joist with large notch

[Tom Mawson]

Hi, I am in need of a bit of advice on the best way to add strength to one of my joists that has had a large notch cut out of it.

Basically some moron fitted an en suite (which I have since ripped out) and they notched out one of the joists to accommodate the trap for the shower.

The notch is between 1/3 and 1/2 of the depth of the joist and maybe 4-5 inches long.

My initial plan is to get some 3/8" or 1/2" steel plate the same depth as the joist, one either side of the joist at maybe a foot long, maybe longer, and put 4 decent sized bolts in.

Would this be a bit over-kill? or is there a better solution I could go with

 

[Gerrydelasel]

Fish plates (as you describe) is how it would traditionally be done. But does it really matter? A shower is usually near the wall, and just one slightly weaker joist near the wall isn't a huge structural issue (it's lasted this long!).
If it were me and I was still mildly worried about it I would simply cut a block of wood to fit neatly into the missing piece. The joist then cannot easily compress on the top side.

 

[Tom Mawson]

Fish plates (as you describe) is how it would traditionally be done. But does it really matter? A shower is usually near the wall, and just one slightly weaker joist near the wall isn't a huge structural issue (it's lasted this long!).
If it were me and I was still mildly worried about it I would simply cut a block of wood to fit neatly into the missing piece. The joist then cannot easily compress on the top side.

Your right, it doesn't really matter about adding super strength to it as there isn't a lot of weight in the bedroom now the ensuit has gone. But my main concern is to cut out as much flex as possible.

At the moment the living room ceiling is artex which is probably why it hasn't cracked, but in the future it will be skimmed over and I want to limit the flex for that reason.

I think I will go with your idea of cutting a piece of wood to fit in the gap ad then maybe just get another section of joist and bolt that to it rather than fish plates.

Thanks

 

[vinn]

If the trap is running through the notch how can you block it off?
If the notch is free from pipework then you could force a tight fitting block into it but such blocks of off-cut have a habit of shrinking over time.
You could sister 3/4" rippings of ply screwed either side of the joist, their length depending on access.

 

[Tom Mawson]

Thanks for the suggestions, in the end I went with a plywood sandwich and hammered a block of wood in between for good measure.

As it happens the uneven part of the ceiling is actually on the joist next to it and must just be the uneven artex.

At least I have piece of mind now