Thanks George, that approach was my default option but I was intrigued by the portal frame concept as it looks very elegant, and if it's timber it's easier to work with than steel.
I would like bifold doors across one end and wasn't sure about taking the load from a ridge beam vertically down to the middle of a steel header above the bifold opening. I think it would be better to take the load to the outer corners which obviously a portal does naturally.
The shape and style of building would be quite similar to this:
https://www.wydertimber.co.uk/my-product/northstone-feature-marketing-huddle/
I contacted Wyder but I am out of their region (I'm in Warwickshire).
I did look at steel buildings but they seem quite expensive for what they are? And often ugly!
The site is quite constrained so keeping it to 30m2 is as much to do with that as removing the need for regs.
I want to be able to get a Defender in there so I need to maximise the entrance height, 2.1m ideally.
All I really need to know is:
- what size of I beam and material spec eg OSB etc
- what centre spacing
- what material and orientation for the joint bracing and spec of glue to get the required strength
If a timber supplier can precision cut the beams to the right angles then it's a lovely kit of parts to glue together and erect.