I've decided not to go for them now. It's too far in the future - only just putting plans into building control. They are on ebay, and I'm no longer the highest bidder so I'm out. I would always have had a slight worry about them. I sent a note to BC, who said if I could "show" that the U values were up to regs, I could use them. I may have been able to come to a compromise, but as I said, its all too far into the future. Simon.