Min Distance of Window from existing Wall to new Side Extension

2 Aug 2018
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United Kingdom
New to the forum and need some advice. I understand there is a min distance of 665mm of a window from the external corner exposed to the elements, wind etc, however does this also apply to the other corner where my new side extension fixes to the existing facing wall via a wall starter system. I am building a typical cavity wall installation ( double storey) and would like this distance to be 300mm so that the windows look architecturally in proportion to the existing. Will this be a hurdle with the BS?
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Are you saying you won't actually be having a return, as 300 will be the approximate thickness of the wall?
Hi Tony,yes the wall has a cavity and will be 300 mm in width but the return tied to the existing wall will be 300mm. The return on the outside wall is approx 1m.
Does it have a corner at both ends. Your description implies not.

BTW, its not that you can't have a distance less than 665mm from corners to frames, rather if it is less you may need a stability calculation to justify it.
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only has corner one end which is more than a 1m. The other is tied to existing brick wall. Think of a typical side extension to a property. Thanks
One corner, well there is the answer.

The next thing is architecturally in proportion from the inside or outside?
Having it look better from the inside is always the way to go, regardless of how it looks externally; Form Follows Function, and all that.
From the outside. I have seen houses which look terrible as there is no proportion. Also will be knocking through at a later date, but get the issue with window being not in the middle of the room. So structurally no issues with what I am proposing, may increase to size of one block ( 415mm).
You don't have to have a corner/return - simply if you don't it just needs working out properly (and may require a steel post to help restrain, or a lintel fixed in a certain way, or sometimes the joist fixings can help solve, etc.

The structural engineer doing the structural drawings and calculations should be the one to confirm how to do what you wish, no-one else.
The 665mm (3 bricks) measurement is just a 'deemed to satisfy' provision.

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