How can I sister this joist

[David24S]

Hi,

I have recently removed a 18” x 18” chimney breast from a bedroom.
I need to connect the 2 joists which run either side of the breast together.
The breast is up against a party wall and the joist is also more or less against the party wall.
How can I sister this.
My problem is, I cannot bolt as I cannot get between the joist and the party wall.
I had a thinking but not sure if it would work. See images.

This would entail cutting a length of joist the size of the gap, fixing this to a longer length of joist and fixing this lump in with coach screws and screwing the gap filler at 45 degrees.
Help appreciated.
Image says coach bolts it should say coach screws.

 

[Deleted member 174758]

Resin anchors through the existing joists and into the masonry wall? You may need to introduce a packer between the wall and the backs of the two wall joists - this will need to be treated and wrapped in something like roofing felt.

TBH, though, I think that taking the two shorts out and replacing the lot either with a new joist gapped 70mm off the wall, or a new treated joist resin anchored to the wall with a DPM membrane between it and the wall, would be a stronger solution

 

[Bodgedbuild]

You would probably need to get an engineer to check but I think this would be the old school way of doing it

 

[johnny2007]

Your solution could work.
Make sure you anchor the existing joists to the wall properly, then fill the gap with a piece of timber same size of the joists.
And then connect all of them (two existing joists and gap filler with a longer joist screwed into them.
Or, run a full length joist alongside the existing if you can secure it at both ends, then screw it to existing joists.

 

[cdbe]

I've normally but a new joist in, but have usually had the floor or ceiling out to permit this. The problem with the trimming solution is that often the next joist in has been notched to carry the hearth. Is it really touching the wall? You only need about 15mm gap to get a nut and washer taped to an open ended spanner down - fiddly but doable.

However, it's unlikely that joist being so close to the wall carries any real load so plenty of big coach screws from one side is unlikely to ever cause an issue.

 

[David24S]

So now I’ve discovered I have a twisted joist. Would it be best to run a new on parallel on the inside, one end in the brick work and the other end fixed with coach bolts to the joist before the twist starts.
The chimney breast below will be removed, so the 7x2 on the wall far side of breast will be floating, also the trimmer nearest is 5x2 sat in the wall and nailed to the 7x2 which also will be floating.
So what’s the best solution to this ???