Property in Cornwall build in 1913. Shower room with extractor leading exhaust air in the attic.

Has it to be changed by building regulations?

  • 7
    Common sense would suggest to the outside so the attic does not get too humid.
    – Solar Mike
    Oct 5, 2023 at 9:48
  • Cornwall, where? (There’s a few…) Oct 5, 2023 at 11:37
  • 1
    @AloysiusDefenestrate I'm going to guess the original one, given the reference to building regulations, which is UK terminology (as, to some extent, is "shower room").
    – Chris H
    Oct 5, 2023 at 12:45
  • Guesses are good, but there might be a Cornwall in Arizona… Oct 5, 2023 at 12:59

1 Answer 1


Here in the US, most building code updates "grandfather" existing structures that violate the code. i.e. you're not required to update your structure to meet every new code requirement that comes along. Odds are good that your local regulations are the same.

However, whether building regulations require you to exhaust your bath vent fan outside instead of into the attic or not, common sense says that you should make the change.

With the vent fan exhausting into the attic, all you're doing is moving the moisture problems from the bathroom to the attic. This gives you the advantage of not seeing the signs of the problems in the bathroom. The downside is that the problems are hidden away in the attic where you're not likely to notice them until they're rather severe and may require major surgery to rectify.


Make the change now whether required by building code or not.

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