VAT on Barn Conversions

I have worked for a construction company for 20 years and I thought I knew everything about VAT and building, but this is one I am struggling with.

According to Vat Notice 708 barn conversions are generally rated at 5% for VAT however if no more than 1 single façade of the original building is retained then it can be zero rated.

My question is - What if the whole of the original building is demolished apart from a concrete frame. So no facades remaining just the frame. Is it zero or 5%?

This is not for my company but for a friend who intends to live in the property and not sell it.