01621 810231


Below we’ve answered some common questions about preparing for an air tightness test – giving the target building the best chances of passing first time.

How much does a single air pressure test cost?

Prices start from £200 for a single test; prices from £45 for additional tests carried out on the same day and site.

What if the building doesn’t pass the test?

We won’t charge a fee if the building fails the first test. If it does fail, our engineer will keep the house on test (depressurisation), locate any leaks then seal them up. Our team will then re-test and if necessary repeat this procedure until it does pass.

What information does Air Tightness Testing Ltd. need to carry out a test?

A copy of scaled drawings – to work out the envelope of the building; Design air permeability – these are found off the SAP calculations.

How soon should a test be carried out?

ATTMA, the Air Tightness Testing and Measurement Association, has stated that many buildings – around 70 percent – fail because a test is carried out too early, i.e. before the building is fully complete. This can increase costs because re-tests are often required.

So when should an air leakage test be carried out?

To avoid any unnecessary re-test costs, we recommend a test is carried out after a building is fully complete, inclusive of any ‘snagging’. This means doors and windows are fitted and water and electricity has been connected. However, the test should be carried out without floor finishes and furnishings.

Should the test be carried out after the SAP calculations have been completed?

Yes, the SAP calculations should have been carried out and you should have a record of the target result figure for each building that needs to be tested. This number can be found on your SAP calculations report. It may be detailed as an Air Permeability Figure, q50 or DAP.

What preparations are required for a test?

All windows and doors should be fully fitted and working. Make extra sure they are well sealed prior to any test.

Access doors, including internal garage doors, cannot be sealed temporarily in advance of the test and should be air tight. Close trickle vents.

Bathrooms are often where air leaks are found, so these should be fitted and complete. Before fitting bath panels, extractors, vanity unit covers and any boxing in, make sure air leakage paths are fully sealed.

Skirting boards should be sealed with silicone sealant. For best results, skirting boards should be sealed above and below, since floor furnishings such as carpets will not stop air leaks.

Lights, power and appliances – Light fittings, switches, power outlets and appliances should be fitted prior to testing. Temporary seals are not allowed. Ensure these areas are well sealed.

Kitchens – Leaks are often found around pipework in kitchens. Kitchens should therefore be fully completed, with appliances, extractor fans and boxing-in all in place. Cavities behind cupboards are common leakage areas.

Loft hatches/storage doors leading to roof voids must be fitted with draft excluders.

Rad pipes and manifolds – double check these are sealed.

Temporary seals - which are permitted?

Temporary seals may be applied to:

  • Mechanical ventilation systems eg. extractor fans in kitchens and bathrooms
  • Air conditioning grilles
  • Trickle vents
  • Chimney flues
  • Passive ventilation including sub floor ventilation systems, passive stacks and air bricks.

Supply and waste pipework – make sure all pipework for waste and supply is completely sealed where it enters walls and floors.

Can Air Tightness Testing Ltd. provide advice prior to testing?

Yes. Our friendly, helpful team can offer general air leakage design advice. Call us on 01621 810231.

What other steps can be taken to prevent a test fail?

Make sure all your trades understand the importance of air tightness and precisely how they can ensure it is optimal.

Carry out regular inspections of the building as work continues – ensure workmanship is of a high standard throughout.

Leakage problems often arise because cavity walls are breached during construction – frequently around floor joists. Use the right hangars and fixings to prevent this.

iATS Registered and UKAS Recognised


We are registered with iATS (Independent AirTightness Testing Scheme) and use equipment calibrated by UKAS laboratories. Our testing procedures are also recognised by UKAS.