Preparation And Terms and Conditions

Arrangements that need to be met on or before the arranged date for your Air Pressure Test(s)

Payment is invoiced on the day of the test. Full payment to be made prior to release of the test certificate and report.

Agree Sample Testing Regime

Agree the plots to be tested with the Building Control Inspector. They will apply the guidance given in Part L as to what constitutes the various dwelling types on a given development. They will thus agree the sample sizes for testing for each house type, dependent on whether or not Accredited Constructions Details have been adopted.

Design Leakage Rate

We will require the Design Air Leakage Rate for the building. If you do not advise of a figure we will assume the maximum allowable figure for Part L1 of 10 m3/hour/m2.

Provide Drawings

We need to be sent copies of the floor plans and sectional drawings to scale indicating room heights (ideally by email) of the plots to be tested, so as to be able to check volume and envelope calculations. A site plan is also useful to enable us to give guidance on orientation and the testing regime that Building Control will probably require.

Test Preparation

Ensure that the completed building envelope is finished. All doors, windows, and cladding must be installed, or if items such as glazing are missing due to a broken pane, they should be sealed up to prevent air leakage. Care must be taken not to create 'deviations' from the air testing methodology. If you are in doubt please email or call to discuss any possible deviations otherwise these can attract a failure from the outset.


Upon arrival to site, our Engineers will need full access and control of the plots to be tested. It is preferable that other trades vacate the plots for the short duration of the test. We require 2No. 240v Electric sockets within 25 metres of EACH of our testing equipment set up. If the door chosen for the test has a large opening greater than 1.100m x 2.100m high you will need to modify the opening to suit our standard template. (Please call us for advice should this be required.)

On Site Assistance

Please 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 and board material etc. would be useful in case areas need to be sealed. Again care must be taken not to create 'deviations' from the testing methodology.

Weather Conditions

Testing cannot take place in high winds or if significant temperature differences persist from inside to outside the building, particularly for high buildings. Thus the building should not be heated, particularly in winter months.

What we can do to help you on site

  • Checking and assisting with any remaining minor temporary sealing.
  • Ensuring all doors, windows, vents, etc. are opened/closed as appropriate.
  • Manpower needed to set up and run all test equipment and carry out leakage diagnosis unaided.

What we cannot do on site to help

  • Shutting down and temporary sealing all air-handling systems.
  • Provision of safe access for inspection.
  • Remedial sealing work (unless contracted).

Test Preparation – Additional Guidance

Ensure that the completed building envelope is finished. All doors, windows, and cladding must be installed, or if items such as glazing are missing they should be sealed up to prevent air leakage. Please note that temporarily sealing items with tape should be limited to those items detailed in item 1.

  1. Seal with tape (duct tape or air testing tape not masking tape) or cardboard any duct work and mechanical vents to the outside. Pay particular attention to air conditioning systems.
  2. 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.
  3. Seal all SVP and waste pipe penetrations passing through external walls and ceilings. 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. Bath panels should also be fully sealed as ready for use.
  4. Ensure that all toilets and U bends in sinks have water in them.
  5. Ensure all external doors and windows are closed fully and make sure all trickle vents are closed or sealed as applicable (TSL1). Internal doors should be wedged open.
  6. All penetrations through floors & ceilings should be sealed.
  7. The boiler flue must be sealed where it penetrates walls or ceilings.
  8. 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.
  9. Smoke vents are to be closed but NOT SEALED.
  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 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 wallboard and passing above the ceiling board into the roof space.
  11. 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. The full test fee will be payable.
  12. If you require further advice - Call (landline) 01792 424569; (mobile) 07986 099438 or email [email protected]

We take the pressure – so you pass! Don’t leave it to late – plan for the air test now!