Frog and I have welded, well he welded and I held bits and looked away, the frames for my shed. It will be 6m wide and 7m long with two roller doors 2.8m wide. The front and centre bearers are I-beams aquired for very little money. Ordered and delivered, but never picked up, a 12m 150mm x 200mm beam is something you would get pissed off tripping over every day and Frog was happy to take it in a stock-take clearance.
The use of an I-beam for the middle bearer means that there is no post required in the middle of the shed. If we had a 5.9 metre wide roller door we could have skipped the centre support there too.