I have been looking at moving house so I’m doing a fair amount of viewings. Based in the north of Scotland, I keep stumbling upon cold roof houses built between the 60s-80s with no fresh air flow I can see. I have seen a few with cold pitched roofs with insulation at the joist level all the way to the eaves, and no soffit vents or roof tile vents. Then today I viewed a dormer with the eaves accessible with a hatch; where the insulation was between the rafters but the floor of the hatch extended to the eaves with insulation on top.

 

Am I missing something? I thought cold roof construction had to have fresh air flow? Evidently these properties were built like this from the start and haven’t had any mould/smells/damage. I appreciate it might be possible with a strict VCL on the warm side of the insulation but in the roofs I have been in I didn’t see any membrane or the like. Or is it because the roofs have less insulation (50-150mm rolls) so the condensation is happening under the roof tile and not under the sheathing, so it is ok?

Actually just noticing this is probably better in the loft forum