I'm getting round building the flat roofed extension (the main building is a block build stable conversion with external wall insulation (PIR) and featherboarding and more or less finished) and am researching costs.

 

The piled foundations are finished with a beam of 300mm wide. We have to have the weatherboard cladding but I'm investigating the best build method. 

 

My preferred builder is a one man band on a reasonable day rate, but he comes intermittently, depending on his other work. Although frustrating sometimes, it might work as I can keep spending under better control now we're not renting. He's very straight, a nice chap and is a very good all rounder and I think could turn his hand to most things. 

 

I started reading about ICF, is that madness? I need something which will not deteriorate if left to get wet. I have no skills except labouring. Are we limited by the width of the beam? Any suggestions folks? 

If you are using a builder, you know, do what he is used to, no paid for learning curve or expensive mess ups  If he does block work go with that...