Is 2.5 m maximum length of lintel? Why?

[avito009]

I read this in Gordon's book "Structures or why things don't fall down". I read that the maximum length of lintel should be a maximum of 2.5 metres. Why? What if its more?

 

[Infinitybyzero]

The way you're quoting it is very ambiguous. What material? What kind of bonding agent (if masonry)? Is it load bearing?

I'm guessing, based off your limited information, is that 2.5m is an architectural constraint due to the relatively tight fit that doorways require. If you start spanning an opening more than 2.5m (8ft), standard wooden trim/door frames, you could have sag issues.

But, from an engineering stand point, there's no reason you can't have an opening wider than 2.5m. That's what we have "header beams" for. I guess it would be nice to know if he's comparing a header beam to a traditional lintel (headpiece on 2 columns).

 

[CWatters]

I don't have the book but the only thing I can think of is that steel universal beams are preferred over concrete lintels for larger spans.

 

[ebos]

Perhaps you are thinking about standards housing construction, ie wood. I would imagine the standard is 2x8 or 2x10. I don't have my book handy but I would think 2x10 would work for a 2.5 metre opening. Maybe 2x12. But that isn't to say that other materials can't be used. For example, they make super strong laminated beams now that can be used for much more than 2.5m. You need to find out what you need a 2.5m (or greater?) lintel for. And then find the right specs in your area.