Do recirculating cooker hoods pass building regulations?

No. A recirculating hood only filters grease and some odours and does not remove moisture, so it fails Approved Document F on a new kitchen extension. If you want a recirculating hood for looks, you must add a separate ducted extract fan rated at 60 litres per second elsewhere in the kitchen.

What extraction rate does a kitchen extractor need to meet?

Approved Document F sets a minimum intermittent extract rate for a hood directly above the hob, and that requirement doubles if the extractor sits elsewhere in the room. Which? suggests sizing for 10 to 12 air changes per hour, so a large open-plan kitchen needs a higher rated hood than a small one.

Should kitchen ducting be rigid or flexible?

Use rigid 150mm smooth-bore ducting. Flexible ducting bends around obstacles but its ribbed interior creates turbulence that cuts airflow and adds noise, with every metre and every sharp bend reducing extraction capacity noticeably.

Why must extractor ducting be planned before first fix?

The duct route through a ceiling void has to be installed before the ceiling is plasterboarded, and the power supply must be wired during first fix. Once the ceiling closes up, retrofitting means ripping down plasterboard, rerouting, and replastering.

How much clearance do you need between a hob and an extractor hood?

Electric and induction hobs need a minimum clearance to the bottom of the hood, and gas hobs need more. These minimums are set by the manufacturer and safety standards, so always check your specific model's manual because some require a larger gap.

How much should I budget for a kitchen extractor and ducting?

The hood itself is typically £300 – £600, with around £150 – £400 on top for the ducting and core drilling. The unit is usually the smaller part of the bill; ducting complexity and labour drive the rest, and island or downdraft hoods cost considerably more.

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Phase 5 · Specification · Task 05 of 06

Kitchen Extractors and Ventilation

Plan your kitchen extractor ducting route before first fix. Covers extractor types, Part F ventilation requirements, ducting materials, and the three-trade coordination that catches most homeowners out.

11 min readUpdated 2026Premium

Process infographic showing the three-trade extractor coordination timeline: builder cores duct exit, electrician wires power supply, kitchen fitter installs the unit

Prerequisites

Complete these first

Your extractor is not just an appliance. It's a system that cuts through walls, runs through ceiling voids, involves three different trades, and must comply with building regulations. And it's the single most common source of coordination failures in a kitchen extension.

The problem is timing. By the time most homeowners start thinking about their extractor, the electrician has already first-fixed the power supply in the wrong place, the ceiling is plastered over the only viable duct route, and the builder has moved on to the next job. Retrofitting after the ceiling is up costs hundreds of pounds and leaves you with a bodge.

What follows is what you actually need to decide, when you need to decide it, and who needs to know.

What this guide covers

01Why extractors cause more problems than any other appliance
02Types of kitchen extractor
03Building regulations: what Part F actually requires
04Ducting: the part that actually affects your build
05The three-trade coordination problem
06Brand-specific surprises
07Clearance and positioning
08Noise
09Grease filters and maintenance
10What this costs
11The checklist: what to do and when

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