Are structural calcs required for patio doors?

[MattCocken]

Hi All,
We've recently had a single story rear extension built on our house. It has a pitched roof, with bi-folding doors in the wall under the gable end. The doors are 3600mm wide, the whole extension is 5500 wide.
There are no joists resting on the wall above the doors - do we need to provide structural calculations for it? As far as I'm aware the builder used a lintel and not a steel beam as there is no load on the wall - does that sound like a breach of buildings regs?
Thanks for the help,
Matt

 

[freddiemercurystwin]

Did you do this extension under Building Control approval?

 

[MattCocken]

Yes, under buildings control. Extension is complete, and I can no longer reach the builder that did the work (has vanished off the face of the earth apparently). Weeks after "completion" the buildings control has only now asked for structural calcs for the beam over the doors, despite site visits during the build. I didn't think it needs calcs as it's not a load bearing wall? I also don't think an RSJ was used, just a lintel.
Matt

 

[tony1851]

There are no joists resting on the wall above the doors

There must be something resting on the beam over the doors; I'm intrigued - could you post a pic or diagram?

 

[wessex101]

If the opening is 3.6m wide with very little loading it is possible that a larger proprietary pressed steel lintel would have been adequate. You would have to find out what lintel was used and make sure that it can support the load from the manufacturers technical details.

Bit worrying that the builder has done a runner. I guess the only way you can find out what was installed is to open it up and have a look.

I assume the work was done under a Building Notice which is why Building Control are querying it now.

 

[MattCocken]

I don't think it was done under a buildings notice. Plans were submitted beforehand along with structural calcs for the opening made in the previous external wall. Site visits were carried out throughout the building process and only after it was complete did the control officer ask for calcs for the above the doors. Should the officer have inspected the lintel during construction?

The joists for the pitched roof are on the side walls of the extension, not above the patio door. There are just a few courses of bricks/blocks forming the gable end above the doors. Image (hopefully) attached.

So you think the only thing to do now is open up the wall and have a look at the lintel? Will it be easy for someone who knows what they're doing to tell what it is from a small hole in the plaster or will it require major work?
Thanks,
Matt

Untitled

• MattCocken
• 6 Aug 2014
• 1

 

[freddiemercurystwin]

Yes the inspector should have looked at the lintel/beam as it was being installed. So is the roof trusses? Or is there a ridge beam sat on the wall? Are the bi folds supported off the floor or hung off the lintel? Each is possible. Whilst a wall may not be considered 'load bearing' in the literal sense you still at least have a chunk of masonry to support and the beam/lintel needs to be adequate to support it. Trying to claim its non structural is a red herring.

Often, when a lintel is specified it eliminates the need for additional calcs. Which begs the question what was specified on the drawings that you submitted?

Presumably they are withholding the completion certificate?

If ultimately physical inspection is required then yes exposing the end(s) of the lintel will be required, to see what was fitted and check the bearing.

 

[tony1851]

Looking at the rear elevation, the lintel is supporting the triangular gable wall above.

Building Control will ask for justification of the lintel in that case.

You can actually do this yourself with a little time and patience - you don't need an SE to do the figures for you (regardless of what Building Control might say).

 

[MattCocken]

There was no lintel specified on the drawings submitted. I guess I'll have to speak to the planning officer and find out if he inspected the lintel at the time. if not I guess I'll have to pay someone to expose it and tell me what it is.

 

[freddiemercurystwin]

Jeez, so they gave you a Full Plans Approval for the Building Regs drawings that were submitted before works commenced on site and the fact that your drawings didn't specify a lintel didn't raise an eyebrow, I would be considering speaking with the Head of Building Control, because some heads need bashing together!

Just for clarity, you're not confusing your Planning Application and a Building Regulations Plan Application?

 

[wessex101]

Just for clarity, you're not confusing your Planning Application and a Building Regulations Plan Application?

I was thinking that. The example posted above is a very basic plan for Building Regs. and to get full plans approval without specifying the lintel? Most irregular.

 

[endecotp]

It's August, your builder is probably on holiday. Unless you're worried that it's about to fall down, just wait for him to get back!

 

[MattCocken]

Ha, My builder's been on holiday for over a year then!
I've got someone to check the lintel used - it was easy enough. It's a 225 x 300 36kg universal beam. I've been told that this is more than enough to support the weigh involved and will have no problems with the buildings regs. Does anyone know if I need to now pay a structural engineer to do some calculations? Or can I do them myself?
Thanks, Matt