Air Tightness Testing

What is air tightness testing?

Air tightness testing or as it is commonly known as either air permeability, air pressure or air leakage testing is carried out to confirm the air permeability rating of the dwelling or building as required by Part L of the Building Regulations. The result is used within the SAP Calculation or SBEM to calculate the energy efficiency rating for all new domestic and non-domestic buildings.

The onsite air test measures the amount of uncontrolled air movement through the building’s fabric such as cracks, gaps, holes and voids. The testing is non-destructive and usually takes up to 2 hours to complete for a single dwelling with the results being confirmed immediately onsite and the certificate issued same day.

Want to know more about air tightness testing, get the complete low down on the why, how and what. To learn more click here.

Residential Air Testing Service

  • 15 years air tightness experience 

  • Instant onsite test results

  • Sameday certificate issue

  • Free pre-test checklists

  • Free pre-test telephone support

  • Free sameday re-test in the event of a failure

  • Smoke testing for leak detection


New Build Domestic & Residential Dwellings (Part L1a)


Newly constructed dwellings are required by, Part L1a of the building regulations to preform a mandatory air tightness test prior to completion of the dwelling to confirm the "as built" air permeability rating.

Upon completion of a dwelling the "as built" SAP Calculation and Air Permeability score is used to prepare the Energy Performance Certificate (EPC).

Very professional advice, friendly prompt service. Quick delivery of all certificates needed to complete building project.

B Foster - Farnham

Non Domestic Commercial Buildings (Part L2a)

Newly constructed non-domestic commercial buildings including care homes, schools, public buildings, offices, shops, industrial units, warehouses and healthcare buildings. These are all required by Part L2a of the building regulations to preform a mandatory air tightness test prior to completion of the building to confirm the "as built" air permeability rating.


Upon completion of a building the "as built" SBEM Calculation and Air Permeability score is used to prepare the Energy Performance Certificate (EPC).

PassivHaus or Passive House Air Testing

Our engineers are able to air test to PassivHaus standards and provide the n50 score. Unlike air testing for building regulations PassivHaus is measuring the air changes per hour which needs to be below 0.6 ACH @ 50 pascals and is the average score of both the property being pressurised and depressurised.

Due the demanding levels set by PassivHaus, typically testing is preformed at various stages throughout the build to ensure workmanship and integrity of installed membranes. These usually include:-

  • 1st Test - Roof on, windows and doors in and membranes installed

  • 2nd Test - 1st fix complete pre plasterboard

  • 3rd Test - 2nd fix complete pre painting & decorating

  • Final Test - Building complete ready for occupation

Contract Sealing Installation Service

Certified installers of both textile and liquid applied airtight membranes. We can supply and install on small or large projects which are committed to achieving low air test results. Typically these projects are focused on low or zero carbon emissions and our team of experts can help you succeed.

Passive Purple Brush.jpeg

Additional services we offer to support airtightness:- 

  • Pre test site inspections - identify problem areas and help you pass first time

  • Design reviews - review drawings to ensure the robustness of the air barrier continuity 

  • Contract air tightness sealing - installation of specialist air tightness membranes

  • Air tightness sealing products - air tight products, membranes and grommets for purchase

Why Use BEAT?

BEAT Solutions are registered members of iATS scheme which means all our staff are able to provide certificates which are guaranteed to be accepted by all local building control inspectors. All our testing equipment is annually UKAS calibrated to ensure measure accuracy.

When should I have my air test?

The air test should be conducted once all the building works are complete, this includes painting, decorating and floor coverings. Don't rush and get your air test too early. This increases the likelihood of a failure. We have a saying here at BEAT Solutions to establish whether the building is fit for testing. "would you let a paying customer move in yet?" If you can answer yes to this simple question, then it's is likely the building is ready.

How long quickly to i get my result and certificate?

The air test result is calculated onsite and for all air tests completed before 4pm we issue the certificate the same day via email.

What do we need to undertake an air test?

We require drawings including floor plans, sections, elevations and site plan to enable us to calculate the buildings envelope area. Additionally we'll require a copy of the design stage SAP calculation to establish the assumed air permeability score.

What happens if my air test score is too high and fails?

We are focused on helping all projects succeed. Therefore if your test fails we'll identify the areas that are leaking using the latest diagnostic equipment and techniques. We'll then allow yon upto 30 minutes remedial time to resolve the problematic areas and will re-test again for FREE. This is usually sufficient for most projects to achieve the required pass result. If for whatever reason the remedial works aren't to be completed during our visit, then a separate rechargeable retest will be required.

How to i get a quote?

Just send us your project drawings via email to or use our quote request form and we'll send you an electronic quote by return.

How long does an air test take?

Depending on the size of the building the following can be used as a guide:- Small house or flat = upto 1.5hrs Large House = upto 2hrs Small commercial units i.e office, shop = upto 2hrs Medium commercial units i.e carehome, school = upto 4hrs Large commercial units i.e office blocks, hotels = upto 6hrs

Can you test multiple plots or units on the sameday?

Yes, generally as a guide we can test upto 10 plots in a single visit. For large volume projects we can test over multiple days if required.

What about my extractor fans and trickle vents?

The purpose of the test is to measure the amount of uncontrolled air movement. Therefore you are required to temporarily seal all extract ventilation fans including whole house ventilation systems. Also all trickle vents are closed, these can be temporarily sealed by the customer if you'd prefer. For further guidance on preparing for an air test see our site readiness checklist.

Frequently Asked Questions