If you’re building a new home, completing a self-build or developing a commercial property, you may be told that an air tightness test is required before Building Control sign-off.
An air tightness test (also known as an air permeability test) demonstrates that a building meets the air leakage assumptions used within the energy calculations required under Approved Document Part L.
This guide explains when testing is required, what happens during the process and how modern Pulse air testing differs from traditional blower door testing.
When is an air tightness test required?
Air tightness testing is commonly required for:
- New build homes
- Self-build projects
- Apartment developments
- Many commercial buildings
- Some conversions and material change of use projects
Your SAP assessor or Building Control body will normally confirm whether testing is required for your project.
Why does building control require an air test?
Modern buildings are designed to minimise uncontrolled air leakage.
Testing confirms that the completed building performs as assumed within the SAP or SBEM calculations and demonstrates compliance with Part L of the Building Regulations.
How is a pulse air test carried out?
Unlike traditional blower door testing, Pulse air testing does not require a large fan to be installed in an external doorway.
Instead, the Pulse system briefly releases a measured pulse of air into the building and monitors how the internal pressure changes over a matter of seconds. Using this data, the equipment accurately calculates the building’s air permeability at normal operating pressures before reporting the equivalent compliance result required for Building Regulations. Pulse testing is an approved alternative test method under UK Building Regulations and CIBSE TM23.
For many occupied buildings and completed homes, the lower-pressure approach can be quicker and less disruptive than traditional fan pressurisation testing.
When should an air test be carried out?
The building should normally be substantially complete before testing.
This usually means:
- External doors and windows installed
- Permanent sealing completed
- Loft hatches fitted
- Service penetrations sealed
- Water traps filled
- Building ready for Building Control inspection
Testing before these items are complete often results in unnecessary repeat visits.
The building should normally be substantially complete before testing.
This usually means:
- External doors and windows installed
- Permanent sealing completed
- Loft hatches fitted
- Service penetrations sealed
- Water traps filled
- Building ready for Building Control inspection
Testing before these items are complete often results in unnecessary repeat visits.
What happens if a building doesn’t meet its design target?
If the measured result exceeds the design air permeability target, remedial sealing work may be required before a further test.
Common causes include:
- Poorly sealed service penetrations
- Loft hatch leakage
- Gaps around windows and doors
- Incomplete sealing at junctions
- Unfinished building works
Identifying these issues early can help avoid delays to Building Control approval.
Air tightness testing across the South West
TargetCO2 provides Pulse air tightness testing for:
- Self-builders
- House builders
- Developers
- Commercial projects
- Building Control compliance
We provide Part L air testing throughout Devon, Cornwall, Somerset, Dorset, Bristol and Bath, with wider UK coverage available for larger projects.
If you’re unsure whether your development requires an air tightness test, we’re happy to provide practical advice before you book.
Contact TargetCO2 today for a competitive quotation.
