Air Tightness Testing Checklist for Residential Dwellings

Before our engineers arrive on site to undertake the air tightness test, please ensure you have sent us the design air permeability figure and been through the checklist below, this will greatly increase your chances of passing your air tightness test the first time. Also you can download our Air Tightness Checklist for Residential Dwellings.

Items to be completed prior to our arrival on site

  1. We will require the Design Air Leakage Rate or Air Permeability for the building. This is generally detailed in the Design Stage SAP report under ‘designed air permeability’ If you do not advise of a figure we will assume the maximum allowable figure for Part L1 of 10m3/hour/m2.
  2. For multiple tests we will require the latest revision floors plans for the building at least 1 week prior to the test date. For single tests we can have the drawings on the day of the test.
  3. We require ONE 240v MAINS powered electrical sockets within 5 metres of EACH of our
    testing equipment set up – usually the front door – we cannot use temporary power or generators.
  4. Ensure that the completed building envelope is finished, to include all doors, windows, walls, floor and ceilings
  5. Please note that the temporary sealing of items with tape should be limited to only those items detailed in item 6 below. All other items should be in their finished everyday use condition.
  6. Seal with tape or cardboard any trickle vents, duct work and mechanical vents to the outside. Pay particular attention to sealing air conditioning systems.
  7. Ensure that all toilets and U bends in sinks have water in them.
  8. Ensure all external doors and windows are closed against their latches.
  9. All internal doors should be wedged open unless they run into unheated areas such as garages or plant rooms.
  10. Have a competent member of your staff available on the test day to modify and/or seal any further areas that we identify as requiring extra work. A good supply of mastic/decorators caulk, expanding foam and board material etc. would be useful in case areas need to be sealed.
  11. If the door chosen for the test has a larger opening than 1.100m x 2.200m high, you will need to modify the opening to suit our template. (Please call us for advice should this be required)
  12. Ideally all the units to be tested should be in a completely finished condition with final mastic applied to the whole unit.
  13. Whilst we would prefer to have the building empty during the test duration, people can
    stay in the building whilst the test is in progress. They may not however enter or leave during the test period. (Approx. 1/2 hour)
  14. We require a parking space for a transit van within 10 metres of the test location on site as we may need to access further equipment.
  15. If we arrive on site and are delayed due to the site not being prepared adequately, or the items in this checklist not being completed prior to our arrival, we reserve the right to cancel
    the test.



Items that can be temporally sealed

We have been on projects where there has been lots of unauthorised temporarily sealing, this is usually the case when the buildings have not been sealed properly prior to our arrival on site to undertake the blower door test. Please note only the controllable air flow pathways listed below can be temporarily sealed during the air tightness test, all the non-controllable leakage pathways must be permanently sealed.

The following areas should temporarily sealed prior to our arrival on site:

  1. Extractor Fans: should be temporarily sealed (Please ensure these are off before sealing).
  2. MVHR terminals: should be turned off and the vents sealed.
  3. Trickle Vents: Should be closed and can be sealed.
  4. Cooker Hoods: Should be sealed from the outside or inside.
  5. Chimneys Flues: Should be temporarily sealed.
  6. Air Bricks: Should be temporarily sealed.


Most Common Areas of Air Leakage in Dwellings

  1. Seal all ducts and penetrations where the main services enter the building – we have
    encountered many tests where a water pipe duct has been left unsealed underneath kitchen
    units. After services have been installed in the duct, seal the rest of the duct.
  2. Seal behind kitchen units at the wall/floor junction.
  3. Seal all SVP and waste pipe penetrations passing through external walls and ceilings.
  4. Make sure that the tops, sides & ends of all pipe/SVP boxing’s are sealed to prevent air leaking into the boxing, and escaping through SVP/waste pipe penetrations. This is particularly important for SVP boxing’s behind kitchen unit. Often the bottom of the SVP boxing is not sealed to the bottom of the floor so the air can escape straight out.
  5. Bath and shower tray panels should be fitted and fully sealed.
  6. All penetrations through floors & ceilings should be sealed.
  7. The boiler flue must be sealed where it penetrates walls or ceilings.
  8. Make sure all external door/window seals (if applicable) are installed.
  9. In some houses, storage cupboards have been built into the roof space. The doors when closed should seal the room from the roof space. Fit draught excluder if necessary to top, bottom & sides of door/frame.
  10. In houses constructed from Timber Frame or where DOT & DAB plasterboard has been fixed to the inside face of block work perimeter walls, the gap.
  11. In between the bottom of the plasterboard and floors needs to be sealed at every floor level. Alternatively the gap between the bottom of the skirting board and floor can be sealed with mastic. This prevents air leaking behind the wall board and passing above the ceiling
    board, into the roof space. attempt.


If you want further information on how how to prepare for your air test, please get in touch 

All dwellings now require to be air tested to achieve building control signoff. We provide residential air tightness testing throughout the United Kingdom. We undertake air testing on all types of projects from apartment blocks containing hundreds of flats, for companies such as Mace, down to the single tests for self-builders. Also, if you have failed your blower door test, don’t panic just contact us and we should be able to help you get a pass and attain compliance with Building Regulations Part L.

We are one of the few companies in the UK that are UKAS accredited for both Air Tightness & Sound Insulation Testing. This means we can undertake Air, Sound and Vent Testing Packages during the same visit, reducing costs and coordination issues for our clients. Unlike many companies we do not subcontract our works.

For more information about our Air Tightness Testing procedure, please visit us at or contact us on 01525 303905 or Alternatively, for more information please download our Commercial Air Test Checklist.