Can I Vent a Rangehood Into My Roof Cavity?
When installing a new rangehood, many homeowners wonder if it’s acceptable to vent it straight into the roof cavity. While this might seem like a quick or convenient option, the short answer is no—you should never vent a rangehood into your roof space.
Why Venting Into a Roof Cavity Is a Problem
Your rangehood’s main job is to capture and expel steam, smoke, grease, and cooking odours from your kitchen. If this airflow is directed into your roof cavity instead of outdoors, several issues can quickly arise:
- Moisture Build-Up: Steam and condensation become trapped in the enclosed space, leading to damp conditions.
- Mould Growth: Excess moisture creates the perfect breeding ground for mould and mildew, which can spread and cause serious health problems.
- Grease Residue: Cooking vapours often contain grease. Over time, this settles inside the roof cavity, attracting dust, pests, and creating a fire hazard.
- Structural Damage: Persistent moisture can weaken insulation, plasterboard, and even timber beams, leading to expensive repairs.
The Right Way to Vent a Rangehood
For your rangehood to function effectively and safely, it must vent to the outside of your home. There are a few common ways to do this:
- Through the Roof: Using proper ducting and a roof vent cap designed to keep out rain and pests.
- Through an External Wall: Ideal for kitchens located on an outside wall, where ducting can be kept short and efficient.
- Through the Eaves: A suitable option when roof access is limited, provided the ducting terminates outside, not inside the eaves.
Each option requires correctly sized ducting (generally rigid, not flexible) to minimise noise, reduce grease build-up, and maximise airflow.
What If External Venting Isn’t Possible?
If you’re unable to duct to the outside—for example, in some apartments—you can install a recirculating rangehood. These use charcoal filters to trap odours and grease before recirculating clean air back into your kitchen. While not as effective as ducted systems, it’s a safer and compliant alternative to venting into your roof cavity.
Final Thoughts
Venting a rangehood into your roof cavity might seem like a shortcut, but it creates serious long-term risks: mould, health concerns, fire hazards, and structural damage. Always ensure your rangehood is vented to the outside or consider a recirculating model if external ducting isn’t an option.
When in doubt, consult a licensed installer to ensure your rangehood meets building standards and protects your home for years to come.
