On Jun 14, 1:47*pm, "mark" wrote:
"Hugo Nebula" abuse@localhost wrote in message

...

[Default] On Mon, 13 Jun 2011 15:46:24 +0100, a certain chimpanzee,
"mark" , randomly hit the keyboard and
wrote:

So can anyone tell me a typical application for each grade of lintel?

It's to do with the loads on the lintel. The catalogues usually give a
safe working load (SWL). Wall loads are about 4.5kN/m^2, floors (in
dwellings) are about 2.0-2.25kN/m^2, roofs are between 1.5-2.5kN/m^2.
Multiply by the areas bearing onto the lintel, add a bit more to be on
the safe side, and you have you SWL.
--

I think I understand what your saying but *working out areas is the tricky
bit for me. *I can do the maths but determining the areas of wall and roof
bearing down on to the lintel is where I come unstuck.
Thanks

mark

The lintel supports the triangle of masonary above it.
Just imagine the bit that would fall out if it wasn't there.
Work out the weight of that.