Garden room/timber frame/bifolds

[23vc]

Evening all, not posted here for a while, hope everyone is well.
I’ve been knocking up my garden room, and have realised I may have made a design mistake so trying to work out my options.
Basically all was good, walls are up (4x2 sheathed with 12mm osb) roof deck is on (5x2s). Issue is, one of the end walls is going to consist pretty much entirely of a 2m wide aluminium bifold. There’s only about 150mm of “meat” either side of it.

Bifolds are paid for but not arrived yet, and I’ve now found that you can “sway” the opening somewhat as there’s very little lateral restraint as it’s completely open ready for the doors. Despite the other 3 walls and roof being up and sheathed in OSB.

Everything is pretty well fixed with 100mm screws everywhere, and short of fitting some big flat steel angle braces at the top corners of the opening, I’m not really sure what to do.

Reckon there’s a way forward here, or is this an invalid design, and I need to rethink the whole thing?

 

[23vc]

Thinking about this I reckon my options are:

1) rely on the steel bifolds to provide rigidity (doubtful?)

2) get some decent heavy duty L plate steel brackets (the flat ones not angle brackets) and fit to each top corner studwork on both sides and use loads of screws

3) fit some kind of separate corner post to one side with a decent depth and amount of concrete to shore it up, would need to get creative with the cladding to hide it

4) fit the bifolds on a different (longer) wall - this is looking like the easiest option but changes the design from how we wanted it

anyway sorry for the ramble but any thoughts appreciated as ever

 

[John D v2.0]

Sounds like no one is replying so you're stuck with me.
The problem would presumably be from the wind load on the side which could be quite strong if it is a significant area. I am sure if you can get long and thick enough right angle plates it could take the load, but if you get a structural engineer to help it might cost more than the materials.
I'm imagining you'd end up needing a steel plate over a metre long each way and a few mm thick.
Good luck with it!

 

[23vc]

Cheers JD similar to my thoughts. I may even fit the bifolds as a trial then assess the situation…

 

[John D v2.0]

Could do but I'd be surprised if the bifold can take any load, actually it would be the other way round. The biolds must have to be such tight tolerances that any movement from the structure and they won't work properly? If it was a solid non opener pane i could imagine it providing some diagonal support but a fully opening frame couldn't do much could it?
Have you thought about adding guy ropes and pegging it down like a tent?

 

[kingandy2nd]

Hey 23vc,

Hope you’re well.

I have some aluminium bifold stored in my garage which I bought on eBay as they were ridiculously cheap, but I don’t have anything to actually do with them!

The frame is really solid so if I were you I wouldn’t be too concerned when closed. However if course a lot of weight is put onto the side the doors open to (assuming they cascade all in one direction)…if the wind caught the open doors and there may be a problem.

I have been using ‘the metal store’ online for supplies for a welding course I’m doing. Perhaps you could order some 5mm angle iron and fix it to your vertical studs around the door and add a lot more wooden noggins to reinforce those parts. The metal store will cut to length for free, so you could order a load of 2.4m (for example) lengths pre-cut, then you’d just need drill and fix them in.

 

[23vc]

Thanks chaps. Will deffo look to order some angle iron/plate but may also try and add a wind post, which I reckon could be what’s needed, shame I’ve only just realised the issue after my nice plinth brickwork, dpm and slab are all done you live and learn.
I’ve built extensions on my own, this is harder as I’m more clueless about timber frame !!!

 

[big-all]

if the structure is up try pushing really hard at the top where the door weight will be
it may take the weight but every creak will be another joint loosening towards failure i am assuming all the weight is on the hinges or is there runners ??

 

[23vc]

if the structure is up try pushing really hard at the top where the door weight will be
it may take the weight but every creak will be another joint loosening towards failure i am assuming all the weight is on the hinges or is there runners ??

they’re top hung doors, fixed to a doubled up 6x2 above and only 2m span so I’m not worried about that so much, more the risk of the whole structure diagonally racking if the wind catches the adjacent wall. I’ve no idea yet whether fitting the doors will help prevent that. Without the doors in, there’s a bit of sideways movement at the top despite the other 3 walls and roof being on

 

[big-all]

sheet material everywhere will help as it stop diagonal movement but in actual fact you have is a box without a lid turned on its side
you have 150mm to the side internally,how much gap do you have and internally anything above the door ??

 

[23vc]

Above the door I’ve got a pair of doubled up 6x2s which span the gap between ceiling and top of door frame. For the sides there’ll be about 5mm gap left and right of the frame between frame and 150mm of upright 4x2s

 

[big-all]

so your only option is steelwork brackets then and a bit off timber shaving to try and fit them in and hopefully hide them ??
but this is fully a guess as i am a wood butcher

 

[John D v2.0]

may also try and add a wind post, which I reckon could be what’s needed,

Just on the wind post topic, this is to stop tall/long walls buckling in the middle under wind load, not to stop racking.
You'd need more like a moment frame, sometimes in big extensions they make a goal post or even a box frame to resist the torque on the joints. Although that would be clearly excessive cost in this case!
Wind post would not have strength against the relevant forces in your case.
Let us know what you go with in the end,

 

[23vc]

Maybe wind post is the wrong term .. see pic
I reckon the pink steel post will stiffen it up if the doors themselves don’t…

 

[big-all]

the trouble you have with a single post is the load is transferred to the ground by leverage so the support point is around 2m away