Overlapping lintels..

[MattChan]

I need to create opening on the left in the picture below.

• Its a single storey building with a pitch roof over.
• The lintel for the opening on the right has a bearing of approximately 250mm each side which ends within about 60mm of the new opening.
• There is a single row of blocks on top of the inner skin of the lintel on the right and the wall plate is mounted on top of that. There are no bricks on the outer skin and the soffit tucks just under the lintel face.
• The new opening is for a door the frame of which is the same height as the outer skin of bricks.

So now the questions for the new opening:

• Can I just use a concrete lintel for the inner skin and rest it on the flange of the existing lintel to get my 150mm bearing?
• As there is no structure above the opening on the outer skin does there need to be any kind of lintel there screw the door frame to etc?

 

[^woody^]

You can do what you propose with the lintel.

Door frames are not screwed to lintels. But you'll need something externally to fix or butt the soffit to.

 

[MattChan]

Thanks woody.

Would a 1200 x 100 x 65 reinforced concrete lintel be suitable for that type of opening which is 900mm wide? The inner skin is a soft thermal block thats easy to cut with a hand saw, would I need any kind of pad stone for the lintel to bare on to? I'm assuming not as there arent any on the other lintels.

 

[^woody^]

Yes that would do

 

[MattChan]

I've just had a chat with Building Control about this and they aren't happy with the proposed lintel arrangement as they want 2 - 3 courses of masonry between the lintel and the wall plate rather than the 1 that I would have room for.

Is it worth me pushing back on this or do I just need to suck it up?

 

[tony1851]

The reason they've asked for the additional courses is that the small (65mm) lintels are usually 'composite', which means that they derive some of their strength from adhesion to the courses above - in effect making a deeper beam.

Just span the gap with a 4" x 4" timber fence post cut to length, or a couple of 4" x 2" timbers screwed together upright. Either of those would be more than adequate to support a course or two, plus the weight of the roof.

 

[^woody^]

The reason they've asked for the additional courses is that the small (65mm) lintels are usually 'composite'

PS concrete ones are not composite, they are designed for the load without relying on any masonry above.

 

[^woody^]

I've just had a chat with Building Control about this and they aren't happy with the proposed lintel arrangement as they want 2 - 3 courses of masonry between the lintel and the wall plate rather than the 1 that I would have room for.

Is it worth me pushing back on this or do I just need to suck it up?

What does the manufacturer's literature say about it? That's what matters and concrete lintels should not need any masonry above them

 

[tony1851]

PS concrete ones are not composite, they are designed for the load without relying on any masonry above.

PS, from a typical manufacturer's brochure:

 

[^woody^]

PS, from a typical manufacturer's brochure:
View attachment 218161

"Best used"? Is that "must be"?
Like the old "150mm bearing" scenario which does not need to be, or "best used" on a nice sunny day?

PS (pre-stressed) lintels (with the chamber) don't need any masonry above. I'm sure that's the case for precast lintels too.

 

[tony1851]

Suppose we'll need to agree to differ?
Anyway, a piece of timber would do fine on that span.

 

[MattChan]

These are the ones I was going for if that makes any difference:
https://www.supremeconcrete.co.uk/p...els-and-padstones/prestressed-premium-lintels

 

[^woody^]

These are the ones I was going for if that makes any difference:
https://www.supremeconcrete.co.uk/p...els-and-padstones/prestressed-premium-lintels

Contact their tech dept. If they say it's OK, building control have to accept it.

 

[MattChan]

Just done exactly that, they were happy and now the building control is happy as long as I have a uniformly distributed load which they seem to think the wall plate is... Thanks for your help guys

 

[MattChan]

Slow progress on this but I have another question..

The blocks are the soft ones that you can easily cut with a hand saw. In the photo below you can see a 50mm deep pocket on the left that the lintel will sit in to and the 100mm remaining piece of wall that will make up the rest of the bearing.

Is it ok to sit the lintel on the small piece of remaining block circled in red or should that be removed to get an engineering brick / pad stone for it to sit on?