What Kitchen Extraction Rate Do I Need?

Approved Document F Requirements (Domestic)

• Cooker hood (adjacent to hob): 30 l/s minimum, 60 l/s for good capture
• General kitchen extract (no hood): 13 l/s continuous or 60 l/s intermittent
• Open-plan kitchen/living: Same extraction rate but consider noise at lower speeds

Extraction by Hood Type

• Standard chimney hood: 300–600 m³/h (83–167 l/s)
• Canopy/integrated hood: 200–400 m³/h (56–111 l/s)
• Downdraft extractor: 400–800 m³/h (111–222 l/s)
• Ceiling mounted: 500–1,000 m³/h (139–278 l/s)
• Island hood: 600–1,000 m³/h (167–278 l/s)

Extraction vs Recirculation

Extraction (ducted): Removes air from the building through external ducting. Most effective at removing moisture, grease, and odours. Required for gas hobs to remove combustion products.

Recirculation (carbon filter): Filters air and returns it to the room. Less effective but easier to install. Not suitable for gas hobs. Carbon filters need replacing every 3–6 months.

Duct Sizing for Kitchen Extract

• 150mm (6"): Standard for most cooker hoods (up to 40 l/s)
• 200mm (8"): High-powered hoods and commercial use
• Keep duct runs as short and straight as possible
• Maximum recommended: 3m with 2 bends

Make-Up Air

Powerful extraction (>60 l/s) can depressurise a well-sealed house, causing draughts, noise, and potential back-draughting of flues. Consider a make-up air vent or passive air inlet near the hob to replace extracted air.