It's a dry loft conversion that didn't feel cold at all when I visited during colder weather. But I didn't inspect whether radiators were on (or for how long) so possibly got the incorrect impression. It looked meat and solid compared with other ones I've seen, but yes, quite thin in proportion to house size. there are two smallish rooms there and a small shower room. Windows velux, double-glazed. Work done after 2005.
Vendor says it's insulated with 'modern foil sheets' (or foil-backed). It doesn't look thick but he was saying how good it was.
Surveyor saying that it's on the thin side and would cost a lot to make it thicker. Another headache, in other words!
I can't see why he has a problem - something about house possibly losing heat - but surely even with any modern conversion it would lose less heat than with unconverted roof? It's a period semi- (c1910) btw.
Also you can close the fire-proof door into the loft (won't be using it much, mainly for storage or occasional extra guest) which will probably stop the house lose more heat when very cold? I'm a novice with lofts as only lived in flats before.
Thanks for reading!