Removing window bay - shortening floor joists

[andyscotland]

We're converting our bay window to a full-height door / window opening. The original plan was to keep the line of the bay, but SWMBO has suggested fitting a flat window instead.

 

I can't work out / find any guidance on what I'd need to do about the existing floor joists. They currently project into the bay and sit on a sleeper wall just inside the inner skin - so will stick out past the new door / window if left unchanged.

 

The bay is not otherwise structural - the walls/roof are carried over it on an RSJ in line with the house.

 

I'm guessing normally you'd build a new sleeper wall to support them in line with the main wall and cut the ends off. But:

• I'm not sure what that sleeper wall would need by way of foundations? The bay is original so I believe the house foundations follow that line.
• I can't see it'll be feasible to dig foundations from inside the under-floor crawlspace (unless I do it Colditz-style with a trowel.... :() , so I think I'd need to remove the outer wall and cut the joists first to get access, but not sure how best to prop the floor temporarily to do that...

 

Alternatively (and I'm fairly sure this is a non-starter...) we are going to build decking externally level with the door threshold. So spatially, I could leave the joists as they are now, continuing under the start of the decking. But obviously would need a robust way to protect the joists from the weather, and to close up the thermal bridge below the opening. Can't really see that there's a way to do that but it'd be a lot easier structurally!

 

I'll ultimately need to put this through on a Building Warrant Amendment, just looking for some pointers on the best way to approach it particularly in terms of practicality and to help us (SWMBO!) decide whether to go this route or stick with the idea of keeping the bay shape. Thanks!

[nod]

What I’ve done in the past is cut the bay joists off in-line with internal brick skin (100 mil short of existing) and attach a hoist hanger either side allowing you to add a joist across the former bay Then add hoist hangers to the new timber to carry the cut down bay joists 

 

[andyscotland]

@nod thanks - like this? Would 50 x 150 be adequate for the joist spanning the bay do you think?

 

How would you support the floor / joists during the work? I could probably drag some concrete blocks into the crawlspace and make a small pile under each joist, packed tight with timber?

 

Or I'm just thinking, if the joist ends can be carried by a timber span could I actually fix the timber across the inside of the wall beneath the joists so that they're sitting on top? E.g.

That would allow me to fix the bay joist into the inner skin first, hard up against the joists, then it would all be fixed in position and I could just demolish the bay / cut the overhanging joists? Obviously would need to fix the joists down and maybe add noggins which I could do fairly easily once the ends were exposed?

 

 

 

[nod]

Yes exactly like that 

I’ve done this on a number of occasions with bays and replacing rotten joists also 

Simpson strongtie are ideal for this