I was thinking it could work well with 200mm MgO SIPs.    I’ve just had a reasonable quote for the sips. I was wondering if a erected steel portal frame would be cheaper than the insulated slab quotes I’ve had?    The area I’m building in is semi rural so I’m thinking I could probably get a good deal. My groundworkers are local farmers.    http://www.nacsba.org.uk/images/shoestring/18_shoestring13_ed-green.pdf   http://www.pentan.co.uk/project/barnhaus/