September 28, 20251 yr Morning folks, We're looking to convert a 40ft x 16ft double skin brick garage with no internal pillars into living accomodation via PP. The current flat roof is being replaced with a 150mm PIR warm roof EPDM covered green/living roof and the span is 4.8mtr. Joist size, we are considering 220 x 75mm spaced at 400mm ctc intervals with a rise of 4inches from back to front for drainage. Would the joists be substantial enough, or would you suggest 2 x 220 x 50mm joists bolted together every 3ft for greater structural integrity? Any help and advice on this self-conversion would be appreciated, thanks folks.
September 28, 20251 yr Nice use of Imperial and metric units, possibly best to stick with metric throughout. You could easily use posi joust/rafter with that span - we are doing 7m at 600mm centers. But you should be having structural engineer input, not designed by a committee of unknowns. Edited September 28, 20251 yr by JohnMo
Create an account or sign in to comment