Air Tightness
Testing
ATTMA accredited — from £95.
ATTMA-accredited engineers, same-day certificates and clear prep checklists so you avoid failures, delays and re-tests. Part L compliant air pressure testing for new builds nationwide.
- Nationwide UK coverage
- ATTMA-accredited engineers
- Same-day certificates when you pass
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Tests Completed
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Domestic Tests From
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Certificate On Pass
What is an air tightness test?
An air tightness test (also called an air pressure test, air permeability test, or blower door test) measures how much air escapes through gaps and cracks in your building's envelope. The test is carried out by temporarily sealing the building and using a calibrated fan to pressurise or depressurise the space, then measuring the airflow required to maintain that pressure.
The result is your building's air permeability rating, expressed in m³/h/m² @ 50Pa — essentially how many cubic metres of air leak through each square metre of building envelope per hour at a test pressure of 50 Pascals.
Why is air tightness testing required?
Under Part L of the Building Regulations (Part L1A for dwellings, Part L2A for non-dwellings), all new builds in England and Wales must undergo air tightness testing. Similar requirements exist in Scotland (Section 6) and Northern Ireland (Part F1). Since June 2022, every new-build plot requires its own individual test.
Uncontrolled air leakage can account for up to 40% of heat loss, increasing energy bills and carbon emissions. A well-sealed building maintains comfortable temperatures with lower heating costs.
What air permeability target do I need?
The maximum allowable air permeability under Part L is 8 m³/h/m² @ 50Pa. However, your specific target is set by your SAP or SBEM calculations at the design stage — most new-build dwellings target 5 m³/h/m² @ 50Pa or below to meet their energy performance requirements.
For Passivhaus projects, the target is significantly tighter: 0.6 air changes per hour @ 50Pa.
Air pressure testing for every project.
From single dwellings to large commercial buildings, PAS 2035 retrofits and Passivhaus certification.
Dwellings
Part L1A compliant air permeability testing for new-build houses, flats, and apartments. We test against your SAP design air permeability target and provide same-day certification.
- Help hit your SAP air permeability target
- Avoid end-of-project delays and Building Control hold-ups
- From £95 + VAT per dwelling
Commercial Buildings
Part L2A compliant air pressure testing for offices, retail units, schools, healthcare facilities, warehouses, and industrial buildings. We coordinate testing around your programme to minimise disruption.
- Offices, retail, schools, healthcare, industrial
- Testing coordinated around your operations
- From £150 + VAT for smaller units
PAS 2035 Retrofit
Air permeability testing for domestic retrofit projects under PAS 2035. Demonstrate the airtightness improvement achieved by your energy efficiency measures and help reduce comfort complaints and moisture issues.
- Pre and post-retrofit testing available
- Demonstrate improvement after insulation and draught-proofing
Passivhaus
Specialist low-target air tightness testing for Passivhaus and low-energy buildings targeting ≤0.6 ACH @ 50Pa. Our experienced engineers can conduct interim tests during construction to de-risk your final certification test.
- Testing to Passivhaus standard (n50 ≤ 0.6 h¹)
- Interim pre-tests available to identify issues early
Pass your air test in one visit.
Clear prep checklists, on-site diagnostics, video fault-finding and same-day certificates — with unlimited re-tests within the specified timeframe.
Full support if a test fails
Unlimited re-tests within the specified timeframe, full diagnostics and sealing advice, plus video diagnostics to find harder-to-spot leaks.
Same-Day Certificates
Keep Building Control and handovers on schedule. We issue your air test certificate the same working day once you pass.
Site Readiness Checklist
We send a simple preparation checklist before we attend so you know exactly when your plot is ready for testing.
On-Site Diagnostics
If your building doesn't meet its target, we identify the main leakage paths using smoke testing and pressure diagnostics, then explain exactly how to fix them.
Practical Guidance
We walk your site contact through our findings so your team knows what to look for on future plots.
Unlimited Re-Tests
Re-tests within the specified timeframe are included. If a test fails, we follow up with video diagnostics to track down harder-to-find leaks.
One Provider, Nationwide
Whether you need testing for dwellings, commercial buildings, PAS 2035 retrofit, or Passivhaus certification — UKBC covers it all.
Common reasons new builds fail.
After thousands of air tightness tests, we see the same issues causing failures repeatedly. Here are the most common air leakage points we find.
Gaps around windows and doors
Poor sealing between frames and the surrounding wall is one of the biggest culprits. Check for continuous sealant beads and ensure no daylight is visible around frames.
Service penetrations
Anywhere pipes, cables, or ducts pass through the building envelope needs sealing. This includes soil pipes, boiler flues, electrical cables, and extraction ducts.
Loft hatches
Unsealed or poorly fitting loft hatches are a frequent cause of failure. Ensure hatches have compression seals and close firmly.
Skirting boards and floor/wall junctions
Air can escape behind skirting boards where plasterboard meets the floor, especially with dot-and-dab fixing. Seal the junction before fitting skirtings.
Recessed downlights
Standard downlights in ceilings below unheated spaces (like lofts) can leak significantly. Use airtight light covers or airtight-rated fittings.
Electrical sockets on external walls
Back boxes on external walls often have gaps around cables. Seal around cables entering the back box and consider using airtight socket boxes.
Three steps to your certificate.
From first contact to certificate in your inbox. Simple, predictable, and efficient.
Send Us Your Details
Share your plans, SAP or SBEM air permeability target, and site location. We confirm your price, send your site readiness checklist, and book your preferred slot.
We Test On Site
Our ATTMA-accredited engineer attends, seals temporary openings, fits the blower door, and pressurises the building. A domestic test typically takes 30–45 minutes.
Test, Diagnose, Certify
Our engineer runs the blower door test, explains findings, and issues your certificate same day. If there's an issue, we identify exactly how to fix it before we leave.
Transparent guide pricing.
Send us your drawings and SAP/SBEM details for an exact fixed-price quote with no hidden fees.
Typical price for a single new-build dwelling up to an agreed floor area, within standard travel distance. Volume discounts available for multiple plots.
- Enhances energy efficiency and reduces heating bills
- Ensures compliance with building regulations
- Same-day certificate when you pass
- Unlimited re-tests within specified timeframe
Starting price for smaller non-domestic units. Larger or more complex commercial buildings are quoted individually based on floor area and access requirements.
- Optimises energy use and reduces operational costs
- Ensures compliance with regulatory standards
- ATTMA-compliant certification
- Enhances market value and sustainability reputation
*These are guide prices. Actual prices may vary based on building size, location, and access requirements. Contact us for an accurate quote.
Get your quote & earliest test date
Takes 60 seconds. No obligation. We'll confirm your exact price and earliest available slot.
Air testing questions.
Everything you need to know about air pressure testing — from what it is to what happens if you fail.
Still Got a Question? Ask Us How many air tightness tests do I need?
Under current Part L regulations (since June 2022), each new-build plot requires its own individual air tightness test. This applies to every dwelling on a development site, not just a sample.
What air permeability target do I need to achieve?
Your target is set by your SAP or SBEM calculations at the design stage. The maximum allowable under Part L is 8 m³/h/m² @ 50Pa, but most new builds target 5 m³/h/m² @ 50Pa or below. Not sure what target you need? Send us your SAP report and we'll confirm.
What happens if my building fails the air test?
We carry out on-site diagnostics to identify the main air leakage points and explain exactly how to fix them. You get unlimited re-tests within the specified timeframe, full diagnostics and sealing advice, and video diagnostics if the initial test fails to help locate any harder-to-find leaks.
When should I book my air tightness test?
Book your test once the building envelope is complete, all penetrations are sealed, and fixtures are fitted. Our site readiness checklist makes this clear. The earlier you get in touch, the better we can advise on airtightness strategy.
How much does an air tightness test cost?
Domestic air tests start from £95 + VAT. Commercial tests start from £150 + VAT. Send us your project details for an exact fixed-price quote with no hidden fees.
How long does an air tightness test take?
The test itself typically takes 30–45 minutes for a standard dwelling, plus time for setup and diagnostics if needed. We issue your certificate the same working day.
Do extensions need an air tightness test?
Residential extensions don't usually require mandatory testing. Commercial extensions over 100m² or more than 25% of the existing building may require testing under Part L2A. Send us your plans and we'll confirm — free of charge.
What's the difference between air tightness testing and air pressure testing?
They're the same thing. Air tightness testing, air pressure testing, air permeability testing, air leakage testing, and blower door testing all refer to the same process.
Do you provide air tightness testing near me?
UKBC provides nationwide air tightness testing across England, Wales, Scotland, and Northern Ireland. We have engineers based throughout the UK.
Can I be on site during the air test?
Yes, we encourage it. Having your site manager or contractor present means they can see exactly what we test and learn from any issues we find. Other contractors can continue work within the property — all windows and doors just need to remain closed for the duration of the test.