Steel cavity lintel sizing

[markrgsr]

Just wondering if anyone can help with lintel dimensions or how to correctly size them. There not massive spans I need one at 1800 long and another at 2200 for a set of 1500 patio doors and a 1900 window.

I've been adviced to use Catnic or IG the wall make up is 100-100-100 cavity. Both skins are block. Above the lintel is one corse of block then straight on to wallplate with a fink trussed roof at 600centres.

There are different duties, standard, hd, extra hd and extreme. I'm obviously looking at standard duty mainly for cost but no one I speak to can tell me how to work it out, the BCO just said it'll probably be ok, and most builders I know have agreed. But how can I tell for sure?

I'm thinking if no one can tell me a method for calculating if I should use standard then brace across the trusses with some 7x2 to ensure better load spread and less chance of sag?

 

[cdbe]

The manufacturers will generally work it out for you FOC if you supply them with basic loading details, and will give you some sums to satisfy building control.

 

[^woody^]

Any wall floor or roof bearing on a lintel will be a standard load for a standard lintel

 

[markrgsr]

Thank you most merchants round here stock IG so perhaps il send them a email. That's the insane thing it was the BCO saying that'll probably do it'll be allright, no interest in calculations or anything....

 

[markrgsr]

Any wall floor or roof bearing on a lintel will be a standard load for a standard lintel

Thanks for your reply Woody, that kind of echos what others have said. What are the heavy grading lintels actually for out of interest? I can't imagine a scenario for the use of them?

 

[^woody^]

If there is an excessive (atypical) loading - say a concrete floor, or a long span floor or roof, point load or masonry that is not spread evenly or at all across the span, then you might select a greater capacity lintel to deal with greater loadings