Ventilation
testing.

What it tests

Approved Document F (Volume 1) of the Building Regulations sets minimum ventilation rates for dwellings. New homes and most significant refurbishments must demonstrate, by physical measurement, that the installed ventilation system meets those rates. The test produces a certificate that Building Control accept as evidence of compliance.

When you need a test

• New dwellings — required for completion certificate and final occupation.
• Significant refurbishments — where ventilation provision is being changed or where a renovation triggers Approved Document L compliance, ventilation must be tested in parallel.
• Whole-dwelling retrofit — particularly where airtightness is being improved (insulation, draughtproofing). Tightening the building envelope without verifying ventilation is the single most common cause of post-retrofit damp and indoor-air-quality complaints.
• MVHR commissioning — mechanical ventilation with heat recovery requires both system commissioning and Part F flow verification.

Systems tested

• System 1 — intermittent extract. Bathroom and kitchen extract fans, plus background ventilators. Each extract point is measured at high and low rate; trickle vents are inspected and recorded.
• System 2 — passive stack ventilation. Less common in modern stock; tested where present.
• System 3 — continuous mechanical extract (MEV). A central or decentralised continuous extract system. Measured at each terminal and against the system’s commissioning data.
• System 4 — mechanical ventilation with heat recovery (MVHR). Supply and extract terminals balanced and measured. Boost rates verified.

What happens on site

The test takes between 60 minutes and three hours depending on the size of the property and the system installed. I use a calibrated, UKAS-traceable powered flow hood for terminal measurements. Each reading is logged with the corresponding zone, system mode and ambient conditions.

Where a system fails to meet its target flows, I’ll diagnose the most likely cause on the spot — ducting kinks, terminal balancing, fan setting, blocked filters — so the contractor can rectify and retest without delay.

What you’ll get

A signed test certificate, a full data sheet of all readings, a photographic record of each terminal, and a covering report explaining results in plain English. Issued within 48 hours of the test.

Why retrofit projects benefit

If you’re tightening a building envelope — insulating, replacing windows, draughtproofing — without verifying the ventilation works, you’re building in a moisture problem. A Part F test at the right point in the programme is the cheapest insurance available against the kind of post-occupancy callbacks that cost real money to put right.