Hi Andrew, the NHBC warranty and the ones from the likes of Zurich last for 10 years.
New homes are specifically excluded from most consumer legislation such as the
Sale of Goods Act 1979. You are still protected by common law and the requirement for a "duty of care" Have a look at this post:
Help/Advice needed please.
You would need to get an expert to say that this wasn't the case, then you could get a quote and recover the money through the small claims court - can't remember what this is called in Scotland. The limit in England and Wales is £5000 - £2500 in Scotland I think - need to check that
Tony