Hi,
Have single storey extension at back of house and had planning approved for some renovation works. Part of that is to have 4.5m (3 panel) sliding doors at back in the single storey part. Had structural engineer design the beam needed and design says :
250 x 150 x 80 RHS with 300mm 8mm thick bottom plate projection galvanised.
I asked why galvanised (other beams being used elsewhere aren't) and he said because will be exposed on outside. I've had him explain this to me a few times now as just can't see why would be exposed on outside, is it not possible to design a beam which will be boxed in from inside and outside. I have tried googling pictures of this and just can't find any. He did say something about supporting the outer skin but when I see other houses with similar spans and most of those being two storey as opposed to our single I am not seeing any exposed beam.
Will go back again but I'm just not getting it. He said could user hammerite galvanised paint to blend it in (house is white so are slider frames) but why is any of the beam exposed. Any help explaining greatly appreciated as must confess still confused.
Many thanks,
Lawrence
Have single storey extension at back of house and had planning approved for some renovation works. Part of that is to have 4.5m (3 panel) sliding doors at back in the single storey part. Had structural engineer design the beam needed and design says :
250 x 150 x 80 RHS with 300mm 8mm thick bottom plate projection galvanised.
I asked why galvanised (other beams being used elsewhere aren't) and he said because will be exposed on outside. I've had him explain this to me a few times now as just can't see why would be exposed on outside, is it not possible to design a beam which will be boxed in from inside and outside. I have tried googling pictures of this and just can't find any. He did say something about supporting the outer skin but when I see other houses with similar spans and most of those being two storey as opposed to our single I am not seeing any exposed beam.
Will go back again but I'm just not getting it. He said could user hammerite galvanised paint to blend it in (house is white so are slider frames) but why is any of the beam exposed. Any help explaining greatly appreciated as must confess still confused.
Many thanks,
Lawrence