changing from wood to steel garage frame

[ferguson1947]

hi got planning passed for a lean to garage with timber posts and beams to support the roof
a builder has suggested steel rsj beams supported on the external walls to save the use of support posts
the garage length approx 5.8m from memory is this span possible withous to huge a rsj
then use the same 200 x 75 rafters to support the box profile roof or add a 3rd beam alone the length to allow smaller rafters?
garage width is 4.4m
if calculations were obtained and building inspector was happy could the build be amended without new planning approval

 

[ferguson1947]

after checking plans distance between walls is 5.3m plus the amount that would rest on both walls

 

[freddiemercurystwin]

So long as the size doesn't change and the overall design doesn't change wildly then don't worry about it.

BC will likely expect calcs for a steel that long, not convinced a steel would be easier, it would end up about 250 deep I'd guess. Just getting it off the lorry and hauled up into position would be a challenge even for a couple of burly of builders.

 

[ferguson1947]

thanks freddy builder just thought it would save us having 4 150mm timber posts down both sides
any advice is welcome