Air Tightness Testing for New Homes and Commercial Buildings
Required under Part L for every new home. We test, find the leaks if the result falls short, and retest.
Air Tightness Testing for Part L
An air tightness test measures how much air leaks through the fabric of a building. It is also called an air permeability or air pressure test. Under Part L every new home has to be tested, and the result goes into the as-built SAP. We test, find the leaks if the result falls short, and retest.
When it is needed
- Every new home. Testing a sample of plots has not been allowed since June 2022.
- New commercial buildings
- Conversions where the SAP or EPC relies on a tested figure
The figure you have to hit
The legal maximum is 8 m³ per hour per m² at 50 pascals. Your design SAP will usually assume a lower figure, often between 3 and 5, and that is the one you need to reach. Check it before you book. If the test comes in above the design figure, the SAP has to be rerun.
How the test works
We fit a fan into an external doorway, change the pressure inside the building, and measure how much air is needed to hold it. Most homes take one to two hours.
Getting the building ready
- External doors and windows fitted and closing properly
- Walls, floors and ceilings finished, with skirtings, sockets and switches fitted
- Pipe and cable holes sealed, and the loft hatch in place
- Kitchens and bathrooms fitted, with water in the traps
- Power on site
If the result falls short
We go round with smoke to find the leaks, you seal them, and we test again, often on the same visit.
What we need from you
- Plot numbers and floor plans
- The design air permeability figure from the SAP or SBEM
- The site address and a contact on site
Price
Priced per visit. Send the plot list and we will quote.
Questions we get asked
When should I book? When the building is finished enough to seal, and before final decoration, so any leaks can still be reached.
Can you do the SAP as well? Yes. The result goes straight into the as-built SAP and the EPC.
Related: Ventilation Testing, Sound Insulation Testing, SAP Calculations.
Email your plot list or WhatsApp us to book.
Book Your Air Test
Priced per visit. Email or WhatsApp your plot list and the design air permeability figure, and we will come back with a price and the dates we can attend.