Deflected lintel over bifold doors

[Andy011]

Hi looking for some advice on a sagging lintel over bifolds.

The doors (3.6m width, masonry one side, timber post the other) are in a 60's single story flat roof extension to the house with rafters (4m span) resting on the lintel. The lintel is a single 3x11' timber and originally there were sliding doors (not structural) with one door stuck that was taking the weight (I realise now). The window company didn't think the stuck door would be a problem and put the new doors in which got stuck pretty much straight away.

A structural engineer specified a fitch plate to bolt to the existing lintel but having got the tiles off the outside and plaster off the inside the beam was thinner than he thought so is now saying a new timber fitch beam (thicker than present) or steel lintel with steel post at one end. The window company also damaged the masonry support so the whole beam dropped by 1" at the masonry end, I've got it propped at the moment so no chance of further movement.

I was hoping to DIY it but not so sure now - any thoughts would be appreciated.

 

[freddiemercurystwin]

So is the new bifold in place then?

 

[noseall]

Hi looking for some advice on a sagging lintel over bifolds.

The doors (3.6m width, masonry one side, timber post the other) are in a 60's single story flat roof extension to the house with rafters (4m span) resting on the lintel. The lintel is a single 3x11' timber and originally there were sliding doors (not structural) with one door stuck that was taking the weight (I realise now). The window company didn't think the stuck door would be a problem and put the new doors in which got stuck pretty much straight away.

A structural engineer specified a fitch plate to bolt to the existing lintel but having got the tiles off the outside and plaster off the inside the beam was thinner than he thought so is now saying a new timber fitch beam (thicker than present) or steel lintel with steel post at one end. The window company also damaged the masonry support so the whole beam dropped by 1" at the masonry end, I've got it propped at the moment so no chance of further movement.

I was hoping to DIY it but not so sure now - any thoughts would be appreciated.

Sounds like the existing structure is a wee bit...ahem...low end?

Have you got any photos?

 

[Andy011]

Yes, bifolds in place, I've managed to get them open since propping, but I would much rather not take them out as the room is open plan into the rest of the house. It's a 60s ex council - I called it an extension because that's what it looks like but it was built with the rest of the house.

Photo of the corner attached

 

[Deluks]

I can't see how you could easily replace that without major upheaval.
Could it be steel plated both sides?

If replacing you'd have to prop ceiling internally, then find a way to keep the bi-folds in place, and fit a very heavy beam over the top. Sounds well awkward!

As the window company gave you bad advice could you get them to come out and uninstall/reinstall the doors (at their own expense), whilst you put a new beam in?

 

[Harry Bloomfield]

I can't see how you could easily replace that without major upheaval.
Could it be steel plated both sides?

Isn't the 3x11" timber, a really poor choice for stability anyway? Timber will expand and contract/constantly change dimensions with the seasons, making it impossible to get the doors to works effectively. The timber needs to be replaced, with a proper RSJ.

 

[cdbe]

Fix the end bearing of the timber lintel, remove that packing piece and check the deflection of the beam (I don't have a clue but someone will advise- something like up to 15mm mid span) - if it's ok fill the void with foam and screw the frame up to the lintel till level. Whatever support you put in there will bend a bit which is why the door should have had some clearance.

Mine has about 10mm clearance at the ends reducing to about 8mm mid span - but that's a lightly loaded heavy duty catnic.

 

[Ivor Windybottom]

There's not much weight above it so it may be adequate. It's how every garage was built back in the day, it's a bit wider but not that different.

I reckon the door company measured each end only, and didn't allow for the amount it sags by, then forced the door into place while you weren't looking, bending it. This may or may not be possible to recover from - if they've permanently bent it then it should be down to them to replace it, they should have downed tools when they saw it wouldn't fit then told you the lintel needed replacing.

I'd put a couple of nails in a very carefully measured distance up from the bottom edge at each end then stretch a very taut string across. See how much it's sagged. If lots then it needs replacing, which will definitely involve some disruption. Polythene sheets are useful!

 

[noseall]

Yes, bifolds in place, I've managed to get them open since propping, but I would much rather not take them out as the room is open plan into the rest of the house. It's a 60s ex council - I called it an extension because that's what it looks like but it was built with the rest of the house.

Photo of the corner attached

View attachment 346486

Jeez! There's not much meat to that return. That would be a massive no-no by any standards.

 

[Andy011]

Thanks for all the replies! We have decided to bite the bullet and replace the beam. Will let you know how it goes

 

[Andy011]

No chance of the window company helping, they changed management after we ordered and the new guy pushed back very hard when the first problems appeared

 

[Murdochcat]

Thanks for all the replies! We have decided to bite the bullet and replace the beam. Will let you know how it goes

Make sure it’s specified properly by a SE or you may not achieve anything positive.

Bifolds won’t tolerate the slightest movement

 

[Ivor Windybottom]

I'm sure the door frame will bend back to straight, once there's a straight hole to fit it into.

 

[^woody^]

Deflection and bending are different things.

Deflection is typically only concerned with finishes, and even excess deflection can be managed.

If you take that packing timber out, that will take the load off the frame. And there is no need to deal with the deflection by upgrading the beam.

Bending, or inadequacy of the beam to take the load is a different matter.

 

[Andy011]

New beam (specified by SE) went in at the weekend, a genie lift and some friends made it relatively straight forward. Fortunately the doors bent back into shape so all good!

With everything back to square I now have a 2” gap above the doors to deal with, hopefully building control will sign off this week