Air Testing New Homes and pre-test inspections

We pressure / air test new homes to obtain Local Authority Building Control approval under regulations set out in the approved document Part L1A

Why an Air Tightness Test is Needed

It is now mandatory that a percentage of all new homes will have to prove that they have passed an air tightness test prior to occupation. This is due to the fact that the majority of homes use fossil fuels to heat them and the construction of airtight buildings will reduce the need for higher fuel consumption thus reducing the carbon dioxide emissions. The rate your property will need to achieve will be determined in your Target Emission Rate (TER). Building control will be unable to provide you with a completion certificate unless an air test has taken place and the correct results been achieved.

What does an Air Pressure Test Involve?

Once the weather conditions have been checked (usually the day before and on the morning of the test) and all SAP details have been calculated, our technician will arrive on site.
The test involves measuring air permeability by attaching a fan to a suitable exterior door and taking a range of pressure and flow readings. The flow speed is increased and decreased in stages. The air volume flow rate through the fan and the pressure difference across the building envelope are recorded at each fan speed. When calculating the air leakage rate, corrections are made for barometric pressure and temperature. Local wind speed should preferably be below 6 metres per second but this will be checked by our engineer on the day of the test.

Before the test is carried out, all heating, ventilation and air conditioning systems must be switched off. All grilles and openings to the outside, including waste pipes must be sealed. Drainage taps must be filled with water. While the test is being carried out, all internal doors must be kept open. It is safe for other workmen to stay in the property whilst the test is being carried out, but they must be aware that the property must stay airtight for the duration of the test (roughly 1 hour).

Once the test has been fully completed, the technician will advise you of whether the property has passed or failed. If for any reason the property failed, the engineer will be able to advise you of where the leakage occurred by using a smoke pencil. If remedial works can be carried out and a retest started within the hour, the retest may be performed at that time subject to the availability of the technician. Once the property passes the air test, the appropriate certification will be supplied in the next 7 working days.

New Home Building regulations need to meet Part L1a requirements

Does every dwelling need to be tested?

For dwelling’s (L1A), air leakage testing is mandatory for a percentage of each building type. Air leakage should not exceed 10m³/hr/m² of the building envelope.

Number of instances of the dwelling type	Number of tests to be carried out on each dwelling type
4 or less	One test of each dwelling type
Greater than 4, but equal or less than 40	Two tests of each dwelling type
More than 40	At least 5% of the dwelling type, unless the first 5 units of the type that are Tested achieve the design air permeability, when the sampling frequency can be subsequently reduced to 2%

What we offer to you or your clients
Air Testing Homes UK Ltd offer continuous support and advice before, during and after the air pressure test, including pre-test inspections during various stages of construction to achieve a greater chance of passing first time as well as on site consultations to improve workmanship to help eliminate air leakage and pinpoint common leakage paths.
For each individual test the full plans and envelope calculations are reviewed by a fully qualified BINDT technician to ensure that the air leakage test is customised for each property and to ensure that it is kept within the DER/TER.
Air Testing Homes will provide the required certification within 7 days after completion of the test which enables you to obtain Local Authority Building Control approval.
In the event of a failure, smoke tests can be performed to help detect problem areas.