Height of wall for wall plate

29 Apr 2007
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United Kingdom
Hi All

We have built our ground floor walls of a 2 story extension and are about to fit the wall plate. Our walls are made of 215mm blocks. We have noticed that when other extensions are built using cavity walls that the inner wall is higher that the outer wall thus allowing for roof timbers. This is not so with our blocks, they are level and we are wondering have we done something wrong?
when the wall plate goes on top of the wall it will raise the inner part of block by 3 inches but will this be enough height for the roof timbers.
Also our architect has specified 50 x 75 wall plate and we are now wondering if that has anything to do with it.
Also our 1st floor joists are supported across an rsj and finish across tops of where the wall plate is to be placed, at the moment the joist are uncut and are protruding past the external side of the wall, we are not sure where to cut the joists? do they butt up to the wall plate? do they sit on top of wall plate and if so by how much?
BC has said that wall plate is held down with morter and straps are conected to the wall and joists, not the plate!!! we find that strange so will be adding straps onto wall and plate as well.
Thanks for any advice
Nelliedee :(
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as i said earlier, i have NEVER come across a wall plate spec that was less than 100mm wide.

some i've fitted have been 100x50mm and some 100x75mm, depending on finished blockwork height.

all need to be tanalised.

ceiling joists normally sit on top of the plate and are cut at an angle to suit the rafter pitch.

if your roof is particularly steep then you will need to raise the plate so that the rafter ends do not interfere with the external masonry.

some older buildings have a corbelled brick eaves detail that has no rafter end protrusion and makes use of rise 'n' fall, knock-in gutter brackets. in this instance the masonry can finish without the need to raise the internal masonry.
Just rung the architect and he said that it wasnt an error!!!! and also that it didnt matter and if we want to put 100 x 75 we can... I think maybe it was an error as the timber yard man had said the same as you and that wall plates are usually 100.

Thanks once more nosesall you are a saint
Nelliedee :)

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