Right, here’s the thing about old extraction fans—they sound like they’re still working, but they’re pulling about as much steam out as a sieve holds water. Found one of those ancient 150mm units the other day, caked in grease and dust, barely moving air. Replaced it with a proper 600mm cooker hood, the kind that actually shifts the moisture before it settles on your walls and ceiling.
Now, the tricky bit: the old extraction hole was too big for the new 100mm duct pipe. So isolated the old opening properly—sealed it off with insulation and made it airtight—then ran the smaller pipe through. Sounds mad downsizing it, but here’s the reality: a 100mm duct is more than adequate for kitchen extraction, especially when it’s connected to a hood that’s doing the work properly. You don’t need a massive hole in the wall; you need the right airflow rate, and that’s what matters.
Result? Mold doesn’t stand a chance anymore. The kitchen walls and ceiling stay dry, condensation clears faster, and the whole room feels fresher. That’s the difference between an old struggling fan and proper ventilation—it keeps moisture from settling where it shouldn’t.
If your kitchen walls are getting dark patches or your ceiling’s getting spotty, it’s usually telling you the same story. Get the extraction right, and half your damp problems disappear. Get in touch if you need that sorted.