Bi fold doors with removable corner post

13 Apr 2013
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United Kingdom

I am looking to do a 7m width, 3m depth single story extension. In one corner of the extension i plan to have bi folding doors (3m x 3m) with a removable post to create an effect similar to this picture. Has anyone had any experience with this? I am hoping to support the structure I could avoid an expensive steel frame around the entire extension. Any advice gratefully recieved - i am really stuck on this one.


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it needs some cantilevered steels or similar, you're gonna need a structural engineer, some deep pockets for you're bi-fold and some even deeper pockets for your structure.
Thanks Freddie,

I think that i may need one set of cantilevered steels - any idea where i can get a rough idea how much they will cost?

I don't really want to fork out for a structural engineer at this stage to find out that it will be too expensive.

If too expensive i may need to build a brick pillar in the corner instead.

I posted from my crap phone earlier and looking more closely the thing is that doesn't look like an extension so assuming its a new build its a hellova lot easier to insert some steels to cantilever out in a new build than in an extensions as clearly the steels would have to start some way back inside the first floor within the existing house. You can cantilever about a third of any length of steel within reason so if the cantilever is 2m you're gonna need a 6m steel, 4m within the existing. Why not just do a slim steel column instead, no need for a masonry column.
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Thanks Freddie,

Really appreciate the help. It is an extension as we are knocking through the kitchen and dinner and then adding something similar on the end. I would need to cantilever 3m so that would mean the steel starting way back in the house. Sounds expensive.

I like the idea of the column but I have not seen a slim steel column used like this before - any ideas where i could get one and see pics of them?

Thanks again
There are lots - google " sliding folding doors around corners "

I'll be doing some later in the year, so have done the research but not decided on any yet

The cantilever could be an issue, as you will need a long section of wall to bear the beam on. It will be OK if you are just coming off the corners of the house

Your column, sized as small as possible by your SE, with a little insulation wrapped around the external corner just sits inside a corner mullion supplied by the bi-fold door suppliers so it just looks like a chunky mullion.

Anything is possible with enough cash thrown at it but really you could probably go on a seriously swanky holiday for the cost of avoiding a column.
Think that room has enough down-lights?! :p

Also there doesn't seem to be any walls under the sliding doors, rather just some superimposed paving sets and a part functioning step.
Thanks Freddie,

I think you are right - this looks like a similar effect for a much more reasonable cost.

Any idea how the roof is supported above the bifold doors for a 3m span either side of the mullion? Is it a simple as two lintels?

Cheers Matt
This exact scenario has been built at a job in Stone, Staffs. I wasn't involved but was invited to look at other work at the property.

I don't know if the drawings can be brought up on-line but the project went through all the usual channels i.e. b.c, planning etc.

Absolutely stunning is the only way to describe the house although in a comparatively 'modest' location.
Thanks Noseall,

Any idea when the project was completed? I might be able to find it online then.

Appreciate the help,


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