Exhausts that end in the roof space
Bathroom fans and rangehoods venting into the roof, and why it matters.
In short: Moist air from a shower or cooktop has to leave the house. Ducted into the roof, it stays in the house and condenses there.
The problem
Rangehoods and bathroom fans that discharge into the roof void instead of outside, a regular find on pre-purchase inspections in Melbourne's north.
What it causes
Condensation on sarking and timbers, damp insulation and mould in the roof, sometimes visible as ceiling staining below.
In new homes too
At a Beveridge handover we recorded an exhaust fan installed with no duct to an outside vent at all.
A related hazard
A gas heater flued with standard PVC pipe is a safety item, not a ventilation preference.
The fix
Duct each exhaust to an outside vent through the eave or roof. It is usually straightforward work.
Written by our local inspection team from work carried out in Beveridge. Licensed building practitioners, Building & Plumbing Commission registration CDB-U 53425.
