Installing a bifold door inside a steel box

FaceHead

I have an opening at the back of the house, which is a c.2.1m x 3m steel box / picture frame, and I have had a bifold door installed in it. 

The guy who installed is a bit of a cowboy (repeated no-showing, and lying about his identity) so I shouldn't have let him go ahead with the job, but here we are. 

The door has been installed with two screws (appear to be those 7.5mm concrete screws) holding it in on each of the sides and the bottom, and nothing holding the top track to the (OSB clad) steel frame. 

This seems fine on the bottom as the base of the steel frame is cased in concrete. I'm not quite sure how the concrete screws could work into steel, and nothing holding the header of the door is a bit worrying. 

The main problems are that 1. The door has some play in it perhaps 10mm on a firm door close - not a massive deal, but it caused the render outside and plaster inside to break off and 2. The roller on the top track drags, rather than rolls. I expect this will drastically shorten the life of the mechanism. 

I assume that the top track dragging is because without being screwed in, the aluminum header bends under its own weight a little. Hopefully getting it secured properly will solve both problems. 

So, how should you secure a bifold door to a frame which is steel all the way around? What sort of fixings are recommended? 

The fitter says (given his track record of no-showing, I have little confidence) he'll return on Monday, so I feel I need to tell him exactly what needs doing to recify the problem.

TIA

grumbler

I think, yes, a long-span frame must be fixed on all sides.  Intuitively, I'd do this at least every 1 meter.

Of course, one can't rely on the opening being square and must use packers to make the frame square.

And, IMO, masonry screws are no good for steel. 7.5mm hole in a relatively thin steel is too big for cutting a decent thread in it.

FaceHead

grumbler said:
 Intuitively, I'd do this at least every 1 meter.

....

And, IMO, masonry screws are no good for steel. 7.5mm hole in a relatively thin steel is too big for cutting a decent thread in it.

Yes for the header the and base the manafacturer said so put "your chosen fixing" at each end and where each c.900mm leaf joins. So two at the bottom seems a bit inadequate, but none at the top completely unacceptable. 

Also agree that masonry screws don't seem appropriate for steel:.They are meant to go into solid concrete, no the 11mm thick flange of the steel. 

So what are appropriate fixings? There are those self drilling screws, but they seem recommended for up to c.5mm steel. Are you supposed to bolt the door to the steel frame before the timber framework goes around it? 

Every YouTube video of installing a bifold door seems to have a brickwork opening or a concrete lintel. Surely a steel above a bifold door is common and people solve this problem everyday. 

grumbler

FaceHead said:

grumbler said:
 Intuitively, I'd do this at least every 1 meter.

....

And, IMO, masonry screws are no good for steel. 7.5mm hole in a relatively thin steel is too big for cutting a decent thread in it.

 the 11mm thick flange of the steel.

How do you know it's 11 mm? Can it be, say, box section RSJ on the sides - with thinner walls?

For thick steel I'd use a tap to cut thread.

donnablossomm

Definitely best to get new installers to have a look if you don't feel confident about fixing it yourself, although I sense a long-span frame is the way to go

FaceHead

grumbler said:

FaceHead said:

grumbler said:
 Intuitively, I'd do this at least every 1 meter.

....

And, IMO, masonry screws are no good for steel. 7.5mm hole in a relatively thin steel is too big for cutting a decent thread in it.

 the 11mm thick flange of the steel.

How do you know it's 11 mm? Can it be, say, box section RSJ on the sides - with thinner walls?

For thick steel I'd use a tap to cut thread.

The frame was designed by a structural engineer to take the weight of the room above. It's a box frame (or picture frame) made out of four members of UC 203 x 46, which (looking it up on the tables) should have a flange thickness of 11mm. I have confidence that the builders who made the opening did that bit correctly

It's the flanges of these RSJs that the door needs to be secured to, and the door fitter has chosen to do this with masonry screws. The only fixing I can actually visualise working would be nut and bolt (with thread locking fluid to stop it shaking loose?). Putting a door or window below a steel lintel must be an everyday activity for some people. 

greenface2

You need more than 2 screws each side . At least 4 each side AT LEAST . No fixing in the top can cause the doors to fall out . Imagine when open how much glass weight is making the thin alli top track twist . use tec bolts to fix into the top but make sure they fit snug and miss the runners when opening and closing . I always laser level any bifolds . You have what I call goal posts to secure the rooms above , required if there is going to be a shift above and a linel if any not adequate . sound like the goal posts is right but the fitting is dangerous . ( I fit at least one set of alli bifolds a week . Never fit upvc due to future problems from past experience