Structural cast stone window header/lintel

Hi,

We would like to install some bifold doors, with a cast Bath/Ham stone header/lintel for the external face of the opening to match the rest of the house.

We have had structural calculations done. The structural engineer has specified the steels to carry the entire load but has suggested we try to find a cast stone header/lintel that can also carry some load in a 'belt and braces' way.

I can find plenty of companies that can make the header, all of which will reinforce with steel rebar to prevent it from cracking. However, they generally specify their headers as decorative with no defined load bearing capacity.

The only company I can find that gives any form of structural guarantee is Forticrete, who specify 4.7kN/m for their off-the-shelf parts. However, they're not answering my calls or emails - I guess they're trade only?

We can fall back to getting a non-bearing lintel (which is within the structural design), but does anyone know of any other company that can cast a stone lintel/window header with a specified load bearing capacity? If it helps, we're in the Bristol region and the span of the opening will be 2700mm, give or take. So, adding 150mm bearings we're looking at 3m in all.

Many thanks

James

WTF does the SE want a décor stone header to supplement a steel beam? I'd get another SE that knows something about the building trade.

You won't get a piece of stone laid flat, to carry any load over that span. And the engineer was wrong to even suggest it.

Second both the above.
This suggests that the SE is not wholly confident in his design of the steel beam, otherwise why would he have suggested an additional lintel?
As a matter of interest, what steel section(s) has he specified?

Thanks for the replies.

In fairness to the SE he is not specifying that we must have a structural stone header. The load is carried by the steels. He is suggesting that it would be preferable "belt and braces" to attempt to find a stone header that can take some load. His design, though, is based on the steels taking 100% of the load.

His steel spec is "2No. 254x146x31 UB S355 PACKED TIGHT TO UNDERSIDE OF EXISTING MASONRY WITH SEMI-DRY 1:3 CEMENT SAND MORTAR WITH NON-SHRINK ADDITIVE".

Our house is Edwardian - standard vernacular of 50cm solid pennant faced brick walls, detached with 3 habitable stories (although joists run parallel to this wall - so not bearing directly on it) and a clay tile roof.

^woody^ said:

You won't get a piece of stone laid flat, to carry any load over that span.

Click to expand...

Is that why Stonehenge is only a single storey? I was never any good with structural calcs.

stuart45 said:

Is that why Stonehenge is only a single storey? I was never any good with structural calcs.

Click to expand...

I will politely refer you to Hodge's "Brickwork for Apprentices" section 4 - Bonding.

Anyway, a belated Happy Solstice. And get your wellies ready for the summer.

The stone is being chosen for appearance, and the width of the opening makes a real stone lintel impractical.

The ornamental stone will need reinforcement even to be self-supporting over that span.

Have you considered brick soldiers?

@JohnD - You are right, the external stone header is intended to be decorative. Its inclusion in the scheme has been specified by me as an aesthetic requirement. The SE has then proposed a set of steels that will sit behind it and take the full structural load. He has, though, additionally suggested that if the stone lintel is to be there, we should endeavour to get one that can also take some load - although that is not a prerequisite of meeting his design.

I am not proposing a real stone lintel. I am proposing a recast stone lintel. There are a million and one suppliers who will make such a thing (and I am familiar with their work) with sufficient steel rebar that they will warrant it is self supporting over the span.

The additional question here (to which I think the answer is 'no') is "does anyone know of one of these suppliers who will also warrant its load bearing capability?"

No, I have not considered brick soldiers. As I started my post by saying, I want to match with the existing - which, as I've said, is pennant stone with Bath/Ham stone quoins and headers. For this reason, brick soldiers (or indeed, any form of exposed brick - in any colour) would be totally unsuitable.

You could give Castle reclamation in Martock, Somerset a ring. They do make a lot of Blue Lias etc fake flags, and other architectural features, so they may either to able to help you or direct you to someone who may be able to do the job.