Replace joist. Overlap

[mcprinter]

Have rotten joist due to a leaking pipe and need to replace.
I don't think I will be able to fit a full length from wall to wall

1930s suspend floor with brick 'walls' under the floor that the joist rest on.
Joist ends in the walls. Joists are 5" x 2"

Is it acceptable to put an overlap in as per the pic?
If so, is the join best done over one of the supporting walls.
Any particular hardware to use? Length of overlap?

Or is there a better (or correct) way?
Thanks

 

[Mr Chibs]

What length are we talking?

What about sistering the joist? think that's what I'd look at.

Chop away the rotten bit and place the new joist to the side of the old one (what's left of it) and allow a good overlap.
Use timber similar size to original, M12 bolts through old and sister piece, stagger them up and down in the timber depth, use a dog tooth washer (star washer) in the middle of them and square washer on the nut side.

You may have to cut a new pocket in the brickwork, and fill in the old one where the rotten joist was.

I'm sure you'll get some more options.

 

[mcprinter]

It is about 3M long
Most of it has rot. I think the pipe has been dripping for many years.

It is the joist nearest the wall.
Most of the floorboards had rot. Have chopped them back to the middle of the next joist.

I think the whole thing needs replacing.
Could I butt join and use another piece of joist to sister the join?

 

[Mr Chibs]

I'm not a fan of butting it up, as it's another join.
There are things called splice plates, don't solely rely on this.

If there is a decent stub of old joist, can't you sister to said stub on the otherside away from wall?

Is is cavity wall or solid brick?
I ask as you might be able to enlarge the pocket slide full length joist into cavity and then slide back, so bearing is around 100mm.
Then make good pocket with bricks & mortar. Will be cheaper than metalwork for sistering/splicing.

 

[^woody^]

Glue and screw two 9mm ply sections min 600mm long either side of the butted joists.

 

[mcprinter]

Glue and screw two 9mm ply sections min 600mm long either side of the butted joists.

Thanks Woody

Does it matter where the butt is? i.e. mid-air or on a brick wall?

Some pics
I think the extra lump of timber parallel to the joist (Joist3 pic) is something to do with the inset mat.

Might see about getting what I assume is a gas pipe terminated under the floor.
Although it had and will have kitchen units over the top.

This was supposed to be a fairly quick job of helping my neighbour remove an old kitchen and fit a better used one.

 

[^woody^]

It wont matter. The ply solution is as good as any and the least messing about.

You can get metal splice plates to do the same thing. See which is the cheapest option

 

[mcprinter]

Fitted the new joist today
Managed to get it in in one piece by sliding into the adjacent room.
100mm+ supported each end. Wrapped the ends in DPC and used window packers to get it level.

Old one was in very poor condition. Only had to cut 1/3 of the way through to break it for removal.

Advice was appreciated. It gave me the confidence to tackle the replacement