Attaching new ceiling joists over the stairwel

[Lobster]

Further to my (now resolved, thanks) query about joist hangers earlier this week, this project has thrown up another query for which I'd be grateful for some advice.

Basically, I'm infilling the stairwell to reclaim the space for the upstairs room (but not using ropes like the guy who posted about this yesterday!) I've fitted new joist sections perpendicular to the stairs, and maintaining 2m headroom, I want a suspended ceiling up the stairway (ie running parallel to the stairway, 2m above it). This will form a large bulkhead in the room above (partly inside a new cupboard, partly exposed).

What I'm not sure about is how to set up the three joists which will run up the stairs, supporting the new suspended ceiling, ie at the point where they contact my new joists.

ASCII art option (a) shows how I'd like it to look, using 3x2 timber for the angled joists, giving a neat ceiling angle below. However, I feel the angled joists ought to be supported underneath by the new floor joists to give them adequate strength, as in option (b) or maybe (c). But with that option I lose some space in the bedroom as the stairway ceiling will be higher than it needs to be; furthermore, I don't like the ceiling profile this gives.

What to do? I suppose option (d) would work, but that would require stonking great angled joists about 8" thick, which is surely overkill.

Is there be a method of attaching the angled joists as in option (a) in a safe and secure way, which will keep the BCO happy (they will see it in due course). Is there some form of timber-timber joist hanger that would do? One reason I'm concerned about the strength of the angled joists is that the angled area in the upstairs room could be construed as being 'floor' rather than 'wall' or 'ceiling'...

Thanks for any pointers (and thanks for reading this far!)

David

(a)

\ \ ___ \ | | \ \| | \ | J | "J" is the newly inserted \ | | joist, perpedicular \|___| to the stairway (in cross-section)

(b)

\ \ \ \ \ \ \ \ \_____\ | | | | | J | | | |___|

(c)

\ \ \ \ \ \ \ \ _\_ \ | | \| | | J | | | |___|

(d)

\ \ \ \ \ \ _\ \ | | \ | | \ | J | \ | | \|___|

[Mike]

Is the joist exposed on the other side ? If not couldn't you countersink several holes in the angled joist and then pass coach bolts through both joists to implement you option a ? Might need

3*3 instead though. Or better still a 7*3 laid on it's side.

[Lobster]

Yes

Sounds a good idea. Maybe lengths of studding would be better (so as to be able to bolt them on from both ends?

Wow - why so wide?! 2 or 3 of those and I'd virtually have a solid block of 3" timber running up the stairs!

Thanks David

[Rob Morley]

Why not use regular joist hangers? \ \ ___ \ \ | | \ /| | \/ | | |_| | |___|

[Mike]

I think your BCO will trust coach bolts more.

I was thinking of one each side. And 7*3 is actually one of the standard sizes for structural timber from which smaller sizes are often cut. But smaller would be fine.

[Lobster]

Really? OK, I just thought bolts with a large, visible nut on either side of the joists sounded more secure.

I think I may well go for your 7*3 idea, at least for the wall side of the stairs (where I've altready used the masonry->timber joist hangers, because the metal sides of the joist hangers cover the timber joist as far as a couple of inches in (ie, just where a coach bolt would want to go!). So a wider angled joist would let me put a bolt through just past the end of the joist hanger.

Thanks David

[Mike]

There's also 2.5" wide which I think will still present enough 'edge' to get the coach bolt in and not flex to much.