What extraction rate does Part F require for a domestic kitchen?

ADF 2021 Table 5.1a: 30 l/s intermittent (extract adjacent to hob), 60 l/s intermittent (extract elsewhere in kitchen), or 13 l/s continuous. For a ducted cooker hood: 60 l/s; recirculating hood: 30 l/s (but recirculating hoods do not satisfy Part F ventilation requirements on their own). These rates apply to new builds and extensions in England; Scotland and Wales have similar but not identical requirements.

What duct size should I use for a cooker hood?

A 150mm (6 inch) rigid duct is recommended for most domestic cooker hood installations. This minimises pressure drop and noise. A 125mm duct is acceptable for short runs under 3m with no more than two bends. Avoid 100mm ducting for cooker hoods as it restricts airflow significantly. Always use rigid or semi-rigid ducting rather than flexible aluminium hose, which causes turbulence and grease build-up.

How do bends in ducting affect extraction?

Each 90-degree bend in the ducting adds approximately 1.5 metres of equivalent duct length in terms of air resistance. A 45-degree bend adds roughly 0.75m equivalent. For optimal performance, minimise the number of bends and keep the total effective duct length (actual length plus bend equivalents) as short as possible. Most cooker hood manufacturers recommend a maximum effective duct length of 5-6m.

Do I need a carbon filter on a recirculating hood?

Yes, recirculating (filterless extraction) hoods require activated carbon filters to remove cooking odours before returning air to the kitchen. These filters need replacing every 3-6 months depending on usage. Note that recirculating hoods do not meet Part F ventilation requirements on their own — you still need background ventilation via trickle vents or a separate mechanical extract.

What are the extraction requirements for commercial kitchens?

Commercial kitchens typically require 20-30 air changes per hour, depending on the cooking intensity and equipment. Gas-fired equipment requires higher rates due to combustion products. A canopy hood should extend at least 150mm beyond the cooking equipment on all accessible sides. DW/172 (HVCA specification) provides detailed guidance on commercial kitchen ventilation design and is the industry standard in the UK.

TradeCalculator.co.uk

Kitchen Extraction Calculator — Part F Ventilation Rates

Calculate kitchen extraction rates for cooker hoods and mechanical ventilation per Part F.

Kitchen Length

Internal kitchen length

Kitchen Width

Internal kitchen width

Ceiling Height

Floor to ceiling height

Kitchen TypeDomestic or commercial kitchen

Cooking Appliance TypeMain cooking appliance

How We Calculate This

This calculator determines the required kitchen extraction rate based on room volume, kitchen type and cooking appliance, then checks ducting adequacy and Part F compliance.

How it works

Room volume: Length x width x ceiling height in cubic metres
Extraction rate: Domestic per ADF 2021 Table 5.1a (30 l/s adjacent to hob, 60 l/s elsewhere, 13 l/s continuous); commercial by air changes per hour
Effective duct length: Actual length plus 1.5m per 90° bend
Pressure loss: Estimated from duct diameter and effective length
Fan sizing: Based on required extraction rate plus duct resistance allowance
Noise: Estimated from fan type, duct diameter and back-pressure

All calculations reference Approved Document F (2021) for domestic properties. Commercial calculations follow CIBSE Guide B and DW/172 guidelines.

Frequently Asked Questions

Related Calculators

Bathroom Suite Spacing Calculator

Check bathroom suite clearances between fittings and walls per UK building regulations.

Bathroom Tiling Cost Calculator

Calculate bathroom tiling costs for walls and floors including tiles, adhesive, grout and labour.

En-Suite Minimum Size Calculator

Check whether your room dimensions can fit an en-suite with desired fittings and clearances.

Kitchen Plinth Calculator

Calculate kitchen plinth lengths, clips and end caps for base unit runs.

Kitchen Cooker Hood Calculator

Calculate cooker hood extract rate with make-up air provision and duct to external.

Last updated: March 2026

All calculations are estimates. Verify with your supplier.