chimney breast question

[safado]

Knew that if I put breast in the title I'd get more people viewing..............

I have a victorian property and want to put a cast iron fireplace in as there's nothing there at the moment - just a neat fireplace opening .But this space is a little too small height-wise. The old fireplace had been taken out and the fire opening "tidied up" but when the builder did that, to keep everything symetrical he'd lowered the height of the opening by putting in a concrete lintel about 3 cm lower than the original chimney arch.

As far as I can make out (by probing in the mortar under the arch) the iron bar that the victorian builders used to put in under the arch isn't there.

What I'd like to ask is....was that iron bar just formwork to keep the brick arch in place while the mortar between the bricks was going off or was it necessary to support the weight of the bricks above.? I would have enough room to put my new fireplace in if I took out the concrete lintel and I'm thinking that the original brick arch would be enough to support the weight of the chimney breast above (single skin and about eight foot above the arch) - after all that's what arches are for isn't it?

But thought I'd better check first! Any ideas?

Thanks

 

[mater]

it should be fine, if the opening is say 4 bricks wide the amount of bricks placing weight on the arch is 10. 4 then 3 then 2 then 1 in a triangle, the rest of the weight would be transfered to the cheeks .

 

[safado]

Thanks mater - but I didn't quite understand the maths there. The arch is made of vertical bricks. There are 8 forming the arch over the gap of 63cm and then another two at each end - total of 12. Sorry for being a bit dim about this.

 

[mater]

if the opening is 63cm that is about 3 bricks wide if layed lenght ways. your arch is enough to carry what is above.

 

[safado]

Mater thanks mate. By the way if you or anyone's got a mo can you just explain the maths to me - I'm interested to know how it all works. Thanks and a merry christmas to you.

 

[mater]

just imagine a triangle the same width and height as your opening, that is all that is carried by the arch. it is how a standard lintol above a door works, take it away all that falls down is the triangle above

 

[Shytalkz]

But only if there's no opening in the structure above that impinges on the sides of the triangle