Prove the extract meets the gas interlock and planning conditions
Confirmation that your kitchen extract system actually provides the airflow and make-up air your gas interlock and any planning conditions (odour, noise, discharge height) need.
Confirmation that your kitchen extract system actually provides the airflow and make-up air your gas interlock and any planning conditions (odour, noise, discharge height) need. Not a certificate of its own — a check that the extract, make-up air and gas safety interlock all work together as designed.
A gas interlock certificate (CP42) only tests that the interlock switches off gas when the fan stops. It does not confirm the extract rate itself is adequate for your equipment or that your planning permission's odour and noise conditions are met — getting this wrong causes call-backs, planning enforcement, or a kitchen that cannot run at full capacity because make-up air is insufficient.
Ask your gas engineer and your extract installer to confirm to each other, in writing, that the measured extract rate and make-up air satisfy the interlock and any planning conditions.
Who this is for
Any kitchen with mechanical extraction, especially where planning conditions specify odour control or extract height.
What you’ll hold
- Extract airflow commissioning record
- Planning condition discharge confirmation, if applicable
Watch out for
- Treating the gas interlock certificate as proof the extract itself is adequate. It only proves the safety cut-off works, not that airflow is sufficient.
- No make-up air provision, so the extract cannot pull at its rated rate and the interlock nuisance-trips or the kitchen fills with cooking smells.
- Missing a planning condition on extract discharge height or odour control, discovered only when a neighbour complains after you have opened.
Sources
- HSE — Gas safety checked 2026-09-02
- BESA — ventilation and extract guidance checked 2026-09-02
See also
This is item 23 of 66 in the free UK Launch Checklist. See the whole list →