Where does a structural engineers role end? Advice please.

[JonHeath]

Hi all,

I'm building a new extension, where I'm removing aging side passage and conservatory and replacing with an enlarged kitchen (new bedroom also on top). This includes use of a large steel beam to give the open plan feel in the new kitchen/diner.

I will certainly need structural engineer calcs for the new large beam. What I presuming is that I won't need a structural engineer to calculation the lintel/beam above the entrance door, and the new 3m wide bi folding doors on the batch.

The second storey will be built on top of the new entrance door, but the second storey doesn't go above the bi-folding doors.

I've attached my floor plans (existing and proposed for both floors) to show what I mean. The blue highlights where I definitely need structural engineer assistance and the red highlights where I'm not sure. I'm hopeful I don't need it for the red bits and that standard lintels can be calculated and used.

Thanks for your help.
Jon

Existing Ground Floor:

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• 25 Jan 2015
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Existing First Floor:

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Proposed Ground Floor:

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Proposed First Floor:

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[noseall]

I would still have the SE verify the lintel over the bifolds just in case there is a need for a heavier lintel I.e. medium or heavy duty as opposed to standard duty etc.
Also you don't appear to have a masonry return pier on the passage extension so he may need some input here in order to satisfy wind loading and stability issues.
Also you seem to be losing a wall where you extend sideways. Does this not support anything above?

 

[JonHeath]

I would still have the SE verify the lintel over the bifolds just in case there is a need for a heavier lintel I.e. medium or heavy duty as opposed to standard duty etc.
Also you don't appear to have a masonry return pier on the passage extension so he may need some input here in order to satisfy wind loading and stability issues.
Also you seem to be losing a wall where you extend sideways. Does this not support anything above?

Hi noseall - thanks for replying.

The main reason for asking originally was that I was trying to avoid unnecessary costs. The SE's seem to charge per the beam, so getting them to do the lintel above the bifolds was something I was hoping I could avoid. If it needs a pro though, then it needs a pro. There isn't any second storey above those doors.

I was hoping that I didn't need a masonry return, as I was hoping the steel could sit as far on the new bit of masonry (circled in green in the diagram below) as the SE wanted. That can also have foundations to his specs as well.

The wall where I'm extending sideways will be removed to ground level. That section will all be removed down to ground level as it currently only has a ground floor roof on it. See the bit I've circled in yellow below. That is a previous extension to the kitchen. I will be removing it down to the damp proof layer, so keeping the walls down to the foundations and the solid concrete floor of that section.

One more clarification - that section where I have a normal door into the side of the house (highlighted in red on my first post) has a 150mm nib where it joins the old house. Is that sufficient to support the door lintel. I'm led to believe it is. I don't really want to rely on the original foundations.

Thanks again
Jon

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• JonHeath
• 25 Jan 2015
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• 25 Jan 2015
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[tony1851]

As per Nosey, really, though if the bifolds were not too wide - and there is only a lean-to roof above - a standard lintel should be OK.

Building Control may raise an eyebrow when you remove the existing return to that door on the side elevation. You may need to get your SE to prove that a flush wall will maintain stability under lateral wind load - not easy.

 

[noseall]

Building Control may raise an eyebrow when you remove the existing return to that door on the side elevation. You may need to get your SE to prove that a flush wall will maintain stability under lateral wind load - not easy.

Yeah, that's wot I said.

 

[JonHeath]

Cheers for the replies. If it needs a return then I'm OK with that. I'll let the SE advise on that one.