Air tightness testing for new homes
Every new home in England needs an air pressure test. TestConnect finds testers who are already working nearby, checks the plot is ready before they set off, and keeps every result and certificate against the plot.
What an air test measures
An air tightness test measures how much air leaks through the outside of a home: the gaps around windows and doors, service penetrations, junctions, loft hatches and so on. The result is the air permeability, in cubic metres of air per hour for each square metre of the home's envelope, m³/(h·m²).
The usual method is fan pressurisation (the "blower door" test), which reports the result at 50 pascals. The low-pressure pulse method reports at 4 pascals. The approved methodology for both is CIBSE TM23, Testing Buildings for Air Leakage.
What the regulations say (England)
Approved Document L, Volume 1: Dwellings (2021 edition, in effect since 15 June 2022) and Regulation 43 of the Building Regulations 2010 set out the following.
| Topic | What it says |
|---|---|
| Which homes | An air pressure test should be carried out on every dwelling (paragraph 7.4). Testing a sample of plots is no longer an option. |
| Limiting value | Air permeability no worse than 8.0 m³/(h·m²) at 50 Pa, or 1.57 m³/(h·m²) at 4 Pa (Table 4.1). |
| Energy targets | The home's primary energy, emission and fabric energy efficiency rates, calculated with the measured air permeability, must not be worse than its targets (paragraph 7.5). In practice the design value in the SAP calculation matters more than the limiting value. |
| If it fails | The air permeability should be improved, and new tests carried out until the home meets the criteria (paragraph 7.6). |
| Reporting | The results of all pressure tests, including failures, should be reported to the building control body (paragraph 7.7). Notice must be given no later than seven days after the final test (Regulation 43). |
| Who tests | Building control may accept a certificate from a tester registered with an organisation named in Regulation 43(4), currently ATTMA and Elmhurst Energy Systems. The tester should be trained and registered for that class of building. |
| Equipment | Evidence that the test equipment was calibrated by a UKAS-accredited facility or the original manufacturer, within the previous 12 months or as the manufacturer advises; recalibration at least every 24 months is recommended (paragraph 7.2). |
This is a summary of published guidance, not compliance advice. Your building control body decides whether a home complies; check anything you're unsure about with them, or with the tester's scheme. Wales, Scotland and Northern Ireland have their own building regulations.
What changes in 2027
The Future Homes Standard edition of Approved Document L takes effect on 24 March 2027 (24 September 2027 for higher-risk building work). It still says every new dwelling should be tested, keeps the same limiting values, and tightens the notional dwelling used to set the targets to 4 m³/(h·m²) at 50 Pa, from 5 today. Read Part L 2026: what changes for air testing.
How TestConnect helps
- Scheme membership shown: the tester's scheme membership number is on their profile, marked as self-declared, so you can check it with the scheme.
- Route fit: jobs go to testers who are already passing, and plots on one site share a visit.
- Readiness checks: the site confirms the day before, so fewer visits are wasted.
- Honest results: passes, fails and retests are all kept, with readings, defects and photos. Retests link to the first attempt.
- Certificates: the tester lodges with their scheme, then uploads the certificate and lodgement reference against the plot.
Sources
- Approved Document L, Volume 1: Dwellings, 2021 edition incorporating 2023 amendments, and 2026 edition (GOV.UK)
- The Building Regulations 2010, Regulation 43: pressure testing (legislation.gov.uk)
- LABC: air permeability testing
- CIBSE TM23: Testing Buildings for Air Leakage (2022)
- Elmhurst Energy: the Future Homes Standard
Last checked: October 2026.