Subfloor wall repair

[info_45]

We have Victorian terrace. Its a standard layout, so living room at the front, dining room behind and then kitchen at the back to form the 'L' shape. In the back corner of the dining room the floor has dipped. We have lifted a few floorboards and couldn't see very much due to a whole load of builders waste thats been chucked down there (on the to-do list to get this out!). But, we could see that there are two joists which aren't fixed to anything. Its looks as though this is due to a small part of the subfloor wall having fallen away, or at least the bits that the joists would sit on are no longer there. Its in the corner that separates the dining room from the hallway at the back, before the hallway would lead into the kitchen, so I think this is a supporting wall. On the other side of the wall the hallway floor is absolutely solid and flat - this is under laminate so we can't see what's going on here, but my guess is that the joists have somehow been supported on that side, but nobody fixed the dining room.

Whatever has happened, I think, was a long time ago because all of the decoration/skirting boards etc that are in the room are level and the decoration was done long before we moved in. This is mirrored in the room above, because someone has levelled the floor with chipboard and the original boards are beneath, with the dip in that corner.

We're due to do some decorating and whilst everything is muddled it seems like a good idea to address this. I'll be getting a professional to take a look but I wanted to get a general idea of whether this is likely to be a straightforward repair for a builder? I realise there are lots of caveats here and until someone has a proper look they won't be able to tell for sure. But, assuming the best case, would a builder just need to plug some bricks back in with a decent layer of mortar (presumably lime mortar)? If this was one of the sleeper walls that the joists sit on then it would seem much more straightforward, its just thrown me a little bit that its one of the main walls.

 

[Cubist]

Given that you've found some builders waste beneath that floor it may be safe to assume the void has never been directly disturbed by later building work. If that's true AND there is no evidence of a collapsed sleeper wall then its more than likely that the joists were originally mounted in 'pockets' in the load bearing walls brickwork. The neighbouring rooms/hall joists would be handled in the same way. This approach leaves the ends of the joists sitting in these pockets vulnerable to rising damp to induce rot at the end of the timber and ultimately its failure and separation from the wall.

This is a fairly frequent failing of old houses with suspended timber floors and almost all general builders will have the skills to make the necessary repairs. In fact this is one of the jobs that is often handled by the DIYers. The solution requires the removal of a few of the floorboards to provide the necessary access and the installation of a new joist, or section of same sistered to an additional length of the joist joined to the remaining undamaged length of the original, which then sits in the original pocket in the wall. A jack would be used to lift the floor above while the repairs to the joist(s) is made.

 

[info_45]

Thanks for the comprehensive response. If it was a repair to the end of the joist only then I might be prepared to give it a go myself. But, from the limited view I have (this bloomin’ builders waste!) it looks as though there is no pocket for it to actually sit in as there are missing bricks. Perhaps the ends of the joists have rotted as well, but my thinking is that there are bricks missing from the bottom of the wall itself. Would this be just a minor addition to the repair you describe?