Joist end repairs

[fernicarry]

I have a few joist ends that are rotted out and not taking any load into the wall that need repair.

The inner front door is about 18" from the end of the joists and its frame is now taking the load of 2 of the joists, without any particular sign of distress I should add. The third may be resting on top of the internal wall between the hallway and the front room but also no obvious sign of movement above or below. These joists are quite short as they only go to the top of the stairs so really aren't carrying very much.

So far I've sistered one, which conveniently has a much wider pocket in the wall than it needs so that made life easier. I jacked the end of the old joist to get it just clear of the door frame, bolted on the new joist and bedded it into mortar in the pocket. The hope is that when I let the jack off that it won't drop back onto the door frame, or at least less heavily than before. How long should I give the mortar to harden up? Its NHL3.5.

I'm not sure what to do with the other two. The front hallway has a very nice cornice so cutting back any further than the front door is not an option I'm willing to get into. That leaves me with a bit less than 18" to play with from below. Have plenty of access from above as I've lifted the floor boards. Wall is stone rubble construction so making the other 2 pockets wider not likely to be straightforward.

I'm thinking possibly putting dwangs between the joists and resin anchoring those into the front wall then hanging new joist ends on them and bolting onto the existing joists. The inner leaf of the wall is quite loose though so not sure how much of a purchase I can get.

Any other cunning ideas on this?

 

[88v8]

How long should I give the mortar to harden up? Its NHL3.5.

I'm not sure what to do with the other two. The front hallway has a very nice cornice so cutting back any further than the front door is not an option I'm willing to get into. That leaves me with a bit less than 18" to play with from below. Have plenty of access from above as I've lifted the floor boards. Wall is stone rubble construction so making the other 2 pockets wider not likely to be straightforward.

I'm thinking possibly putting dwangs between the joists and resin anchoring those into the front wall then hanging new joist ends on them and bolting onto the existing joists. The inner leaf of the wall is quite loose though so not sure how much of a purchase I can get.

Any other cunning ideas on this?

Bit late....

So you wrapped the joist end in dpc felt and sat it on a bit of slate... about a week I should think, if the mortar was put into damp stone to aid calcification.

Yes the inner leaf of a rubble wall can be a bit precarious.
How far can you drill into the wall?

If you can drill a half inch hole 6" into the wall that would be ample to take a couple of feet of stainless rod which you then clamp along the side of the joist with U bolts.
2" thick joists? These would do it. Two U bolts per joist, big washers to prevent the nuts sinking.

Ivor

 

[fernicarry]

Thanks. I haven't been back to this job yet, always jumping around depending on weather or who's around to help.

The repaired joist end is painted with a bitumen paint and is sitting on slate. The pocket was cleaned of debris and soaked with water before starting. Its been two weeks now so I'll try letting off the jack when I have a moment. Would be good to get the front door closed again...

So far as the other repairs, the modified plan is support the rotten joist ends and cut them off as far in as I can. Then put a new piece across the full repair width as a sort of header joist. Attach stubs to the back of the header and bed those into the pockets as well as resin anchoring into the inner leaf, belt and braces. Then sister the joist ends hanging the sisters onto this new header.

Need to give myself a bit more access from above for this plan which means partly removing an upstairs stud wall (moving the doorway on that wall anyway) so bit more prep needed before I can get going.

 

[88v8]

That would do it for sure. I forgot to ask how much load there's likely to be on those ends, an iron bath at one extreme and an inaccessible corner at the other.

We have an inaccessible corner under a skillin roof where an internal door lintel below has rotted off. It's only carrying a Toblerone's-worth of brickwork, so I just propped it up on a fattened elm door frame.
Sometimes one can legitimately get away with stuff.