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New builds, extensions and testing

Ventilation airflow testing and commissioning

Calibrated flow-hood testing and commissioning sheets for fans, MEV and MVHR.

  • From £145 inc VAT per home
  • Charged visit, price agreed first
  • Airflow tested and recorded
Get a guide price0800 088 6341
Engineer holding a flow hood up to a ceiling valve

Airflow testing measures how much air each fan or valve actually moves, using a calibrated flow hood, and records it against the required rates. It is how you prove a ventilation system works, and for new homes it is part of the building regulations.

How it works

Approved Document F expects mechanical ventilation in new dwellings to be tested with a flow device that has been calibrated within the last 12 months, and the results recorded on a commissioning sheet. The person commissioning should be registered with a competent person scheme for ventilation or show evidence of competence; we tell you who will sign your sheet when we quote.

Testing is also useful outside new builds: it shows landlords and homeowners whether existing fans meet the rates, and it is the first step in rebalancing an MVHR system that no longer feels right.

Options we fit

Extract fan tests

Each fan measured and compared with the Part F rate for the room.

MEV and dMEV commissioning

Trickle and boost rates measured and set.

MVHR commissioning

Supply and extract at every valve measured and balanced.

Remedial advice

If a fan fails, we explain why and quote the fix.

Signs you need this

  • Building control needs a commissioning sheet
  • You are selling a new build and the paperwork is missing
  • Fans seem weak and you want evidence
  • After MVHR or MEV installation by another company
  • A landlord file needs proof of ventilation
  • After rebalancing or extending a system

Guide prices

Airflow testing and commissioning guide prices
WorkGuide price
Airflow testing and commissioning sheet for extract fans (up to 6 fans) (per home)£145–£295 inc VAT
MVHR or MEV commissioning test, every terminal measured and recorded (per system)£245–£395 inc VAT
Rebalance and recommission an existing MVHR system (per system)£245–£445 inc VAT

Guide prices using West Midlands (our baseline) rates. Home prices include VAT at 20%; business prices exclude VAT. A guide price is not a quote: we confirm a fixed price in writing first. London is about 20% higher and the North East about 8% lower.

What happens, step by step

  1. Book

    Tell us the system type and number of fans or valves.

  2. Measure

    Calibrated hood on every fan or valve.

  3. Adjust

    Set or balance where the system allows.

  4. Record

    Results written onto the commissioning sheet.

  5. Advise

    Failures explained with a fixed-price remedy.

The rules that apply

England

In England, ventilation is covered by Part F of the Building Regulations and its guidance, Approved Document F (2021 edition). For homes, it sets minimum extract rates such as 15 litres a second for a bathroom and 30 or 60 for a kitchen, and expects mechanical systems to be airflow-tested.

Wales

Wales has its own Part F ventilation guidance, published by the Welsh Government, and work is checked by building control. We design to the Welsh rates and commission mechanical systems so the results can be recorded.

Scotland

In Scotland, ventilation is covered by the Building (Scotland) Regulations and section 3 of the Technical Handbooks, and most building work needs a building warrant first. We work to the Scottish ventilation standards and record the airflow achieved.

Northern Ireland

In Northern Ireland, ventilation is covered by the Building Regulations (Northern Ireland) and Technical Booklet K. We design to the Northern Ireland guidance and measure the airflow achieved.

Questions people ask

How much does ventilation airflow testing cost?

Testing up to six extract fans costs £145 to £295 including VAT, and commissioning a full MVHR or MEV system £245 to £395.

What equipment is used?

A flow hood that fits over the fan or valve and measures airflow in litres a second, calibrated within the last 12 months.

What happens if a fan fails the test?

We explain the likely cause, such as an undersized fan or a crushed duct, and quote to fix it. Many failures are cheap to put right.

Is testing a legal requirement?

For new dwellings in England, mechanical ventilation must be commissioned and the results given to building control. For existing homes it is good practice and useful evidence.

How long does it take?

Most homes take under an hour; a full MVHR balance can take two to three hours.

Can you test commercial systems?

Yes. We measure and balance commercial supply and extract systems too.

Related services

Modern bathroom with walk-in shower and wall extractor fan

Extractor fan installation

Bathroom, kitchen and utility fans sized to the Part F rates, ducted outside and tested.

From £175 inc VAT per fan

Read before you buy

Airflow testing and commissioning by area

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