Filling in large gaps around pipe work

diogrwydd

Hi all

What would be the best way to fill this gap under the vanity unit of our bathroom? (as well as a similar gap behind the WC). We are finding that the bathroom continually has a lot of dust across most surfaces, and I suspect that a large factor of this is dust and black mortar etc from between the floor cavities being blown / pulled through gaps such as this (1930s terraced house).

[cant't attach images - space is about 8cm x 30cm, with pipe work contained inside as well as some protruding through.

Would expanding foam be appropriate around the hot water and central heating pipes etc? I think there may also be an electric cable near there also?

The cavities are not in view unless you really look etc so finish is not a problem, but would like to make a proper job of it.


Thanks

I_have_spoken

Foam sounds fine for that purpose or cheap and cheerful would be some tufts of insulation from the loft