Building Regs Concerns with Roof for Large 12M x 7M Garden Shed If you want to know how your DIY projects could be affected by building and planning regulations, click here to post questions and view answers

[markbr]

Hi I am constructing a large shed 12M X 7M in my garden to use as a league table tennis venue. An early inspection by the planning officer confirmed planning permission would not be required. However 4 weeks into the build he advised that buildings regs approval would be required! The main concern seems to be the roof which has high collars to maximise ceiling height.The pitch is 22 deg and made from 150X38 timbers with 600 centres full birdsmouth onto the plate . The collars are 0.5 m below the ridge. 3 cranked flitch plates of 100X10 mm steel are fitted at equal spacings and run up the rafter across the collar and down the rafter the other side to prevent spread. total roof area is 100sqM and dead load is 300KN/sqM (felt roof) plus 600KN/sqM snow allowance

The local building control were not satisfied with this and want a structural engineer to look at it. I have a structural engineer on the case and he says I must have purlins to prevent sag. His calcs indicate the purlins will be steel beams weighing more than the entire roof!

My question for the forum is what should we be designing for here? Sag in a domestic setting would be limited to span/240 to prevent cracking of plaster

My question is what is the requirement? Surely the building just needs to be strong enough not to collapse?

[welsh brickie]

you can get roof trusses made to fit that span, eliminating the use for purloins

[markbr]

Too late i'm afraid, the roof was up a week before the planning officer said I needed building regs. He came out to check the ridge height then dropped the bad news a week later