I see on another post that Woody had writen this, is there a minimum size for a corner return as i am building a small extension and my external return is 550mm, this obviously makes the inner leaf even smaller.
Building Corner Returns
- Thread starter staningrimsby
- Start date
I see on another post that Woody had writen this, is there a minimum size for a corner return as i am building a small extension and my external return is 550mm, this obviously makes the inner leaf even smaller.
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yes, there is an accepted minimum, but this is a guideline size that is relevant to an engineers report.
it can be less provided it has been calculated and proven to work by a structural engineer.
there are mitigating factors which could deny such a corner element being strong enough i.e. adjacent patio door sets that are close together.
on the other side of the coin, a corner could work provided there is enough 'meat' left on the opposing corner.
it can be less provided it has been calculated and proven to work by a structural engineer.
there are mitigating factors which could deny such a corner element being strong enough i.e. adjacent patio door sets that are close together.
on the other side of the coin, a corner could work provided there is enough 'meat' left on the opposing corner.
It's very rare that, by judicious adjustment of the figures, a corner less than the stated minimum, can't be proven by calculation. Absolutely no return whatsoever is just about impossible; but, even with that, using different dpc type (hi-load) and if it's greater than a single storey, fine-tuning can make it work. However, in that instance, regardless of the numbers, it is still flimsy and I would put a windpost in; anything from 330 upwards and I've yet to be defeated in making it work - Outer Hebridean wind loads might be problematic though...
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Well the extension only requires two walls to be built the wall containing the french doors is 2.25mtrs long then joins to the existing building via stainless steel wall ties, the french doors are 1.2 mtrs wide witch leaves around 1050mm to play with hence returns of 525mm.
Now the pillar that connectes to the existing wall i could reduce the size of that slightly to compensate for the increased corner return, would this be my best option ???
Although it does need to have enough room to rest a concrete lintel on it to go over the doors.
Now the pillar that connectes to the existing wall i could reduce the size of that slightly to compensate for the increased corner return, would this be my best option ???
Although it does need to have enough room to rest a concrete lintel on it to go over the doors.
Stan, that dim doesn't apply to where you're butting up to the existing building, unless say you had a large opening inside at that point and a piddly dim outside to a return on the existing wall; and then it would be the existing wall that would have to be justified.
You don't have to have a pier/panel extending out from the existing wall, your lintel could take support from the existing wall. Ignore the min 150 bearing for a proprietary lintel, that is only a general requirement, just to make sure that it sits on sound masonry without a padstone.
You don't have to have a pier/panel extending out from the existing wall, your lintel could take support from the existing wall. Ignore the min 150 bearing for a proprietary lintel, that is only a general requirement, just to make sure that it sits on sound masonry without a padstone.
Cheers for that Shytalkz, i think just to play safe i will increase the size of the return to 675mm, i cant be doing with problems at a later date.
Well how can this be when thousands of houses have no returns at all on corners - mine included? And when these were built, there was no requirement for a stupid calculation, and yet all these houses seem to be stilll standing?
And how many modern houses with built-in garages have no return where the garage door meets the external corner?
Have the calculations changed? Because I can't see how such a construction detail can become structurally unsound overnight?
From my 1/2 day structures lesson, I have concluded that a wall 215mm thick or greater, will stand up quite well with no return and a lintel providing the lateral support
I meant a cavity wall 275-300 overall. If the cavity immediately around the return is closed with a thermabate or similar, then that is a tad flimsy, no? Old 9" and upward walls are obviously far stronger laterally, so it's less of an issue.
I agree, the 675mm requirement is somewhat strange and I have no idea where it came from.
I agree, the 675mm requirement is somewhat strange and I have no idea where it came from.
'tis a fail-safe protection from the loads of, wind, snow and abnormal vortices.
probably.
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