Curved brick arches above windows in new extension

[AdamSpringLane]

Hello

Hopefully someone has come across this issue before

Standard cavity wall, 102 external, 100 cavity (50mm Partial Celotex) 100mm inner.
Inner wall needs a straight edge at the top of the window frame
Outer wall needs a curve with a 75mm rise
Window width 1200mm

How do i 'lintel' this? BCO has not given any real advice... ! Apart from they are not keen on using a wooden former...

I have seen the curved arch former's that sit on top of a standard cavity lintel but these are white plastic and the windows are wooden so that won't really work.

Could i put 2 single skin lintels in, one on the block and one directly ontop of the arch so the arch is only supporting itself?

Thanks
Adam

 

[garyo]

Catnic and the like have off the shelf curved lintels but I don't know if they have one to your specific dims. They might do you a special?

 

[^woody^]

Why can't you just build arches?

 

[AdamSpringLane]

Why can't you just build arches?

Indeed, however usually you use a timber former and build around that, but the BCO was not happy with that solution due to the timber rotting, his words.

I have sent an email to Catnic and IG for a quote for curved lintels so will see...

 

[^woody^]

You dont leave the arch former in! Once the arch as set, you take it out. Think about railway bridges and tunnels

 

[AdamSpringLane]

Yes, i did tell him it was only an infill while it was being built. He told me you cannot use an arch for load bearing and it would need a lintel above it so the arch is only supporting itself. It's just trying to find the best solution.

 

[^woody^]

He is talking nonsense, but if you can't deal with that then put a lintel in above the arch. An IG L10 or similar externally and internally the same or a concrete or box lintel.

Or stainless steel expanded metal, but your BCO probably wont have a clue about that either.

If you had just built it without mentioning it, then you would not have this problem with it. Or if the plan drawer had done his job ....

 

[freddiemercurystwin]

Plan drawer? Is there one?

 

[AdamSpringLane]

Plan drawer? Is there one?

No, been done under a notice so no architect plans. Just my own plans on Sketchup.

 

[wessex101]

Building a traditional brick arch is a faff, for starters you've got to make the arch former and find a brickie who knows how to do it.

Buying a special lintel is only slightly more expensive or using a proprietary arch former on a standard lintel makes the process so much quicker and simpler. Other than in listed or historic properties does anyone still bother to build a traditional brick arch?

 

[Notabrickie]

you cannot use an arch for load bearing

Bang goes 4000 years of architecture...

 

[^woody^]

Other than in listed or historic properties does anyone still bother to build a traditional brick arch?

Yes. And its not a "bother".

 

[Newboy]

Somebody needs to have a word with whoever built these non-load-bearing arches

 

[AdamSpringLane]

Bang goes 4000 years of architecture...

Your preaching to the converted... Maybe you should speak to my BCO as he disagrees... Very difficult to calculate the strength of the arch according to him...

 

[stuart45]

That's the problem with arches in the modern cavity wall. You have to prove that the detailing is correct not only in the arch construction but the abutments etc are correct.
That's why all the ones I've seen on site use steel cavity trays and support systems or lintols. A lot of them come in ready made as part of the lintol.