Bi-Fold doors

No the standard width bi-fold door I got from one of the sheds uses flush hinges, not sure thats the correct term. The type that don't need any rebates cutting and one hinge flap fits inside the other when closed. But this type may only be for cheapness and ease of DIY.

What you will need is a runner mechanisium for the top outer end, assuming that you are happy with the door only opening 90 degrees, rather than folding right back towards the wall. You'll also have fun getting everything plumb and square 'cause it won't work well without being both plumb and square. Funny things bi-fold doors...

I suspect that one made from two standard doors might be a bit unweildy. I'm not sure if ordinary hinges will doo for the frame to first door connection either. This shed one uses a pivot pin in the center of the width and the same distance from the end.

A tricky job, I suspect, when you take into account the need for security and weatherproofing. I don't imagine an ordinary builder will be able to do a satisfactory job without specialist help. As to where you get that help... I dunno. Sorry.