To arrange an Air Tightness Test, please contact us.
Air permeability and pressure testing is now mandatory in order to minimise thermal bridging and air leakage. This test will measure the air porosity of a dwelling, demonstrating any leaks in the building fabric. |
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Air Leakage
- Underfloor ventilator grilles
- Gaps in and around suspended timber floors
- Leaky windows or doors
- Pathways through floor/ceiling voids into cavity walls and then to the outside
- Gaps around windows
- Gaps at the ceiling-to-wall joints at the eaves
- Open chimneys
- Gaps around loft hatches
- Service penetrations through ceilings
- Vents penetrating the ceiling/roof
- Bathroom wall vents or extract fans
- Gaps around bathroom waste pipes
- Kitchen wall vents or extractor fans
- Gaps around kitchen waste pipes
- Gaps around floor-to-wall joints (particularly with timber frame)
- Gaps in and around electrical fittings in hollow walls
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Air leakage is measured in m³/h/m² at a reference pressure of 50 Pa between the inside and outside of the dwelling. Approved Document L1A of the Building Regulations defines a reasonable limit for the design air permeability is 10m³/h/m². The Energy Saving Trust adds that a good practice standard is 7m³/h/m² and best practice standard 3m³/h/m². |
How many dwellings should be tested?
It is possible to reduce the number of dwellings to be tested by following Accredited Construction Details (ACDs), an updated version of Robust Details.
In a development following ACDs one test must be carried out for each dwelling type.
In a development NOT following ACDs, the guidelines below should be followed as stipulated in Approved Document L1A of the Building Regulations. |
| Number of instances of the dwelling type |
Number of tests to be carried out on the dwelling type |
| 4 or less |
One test of each dwelling type |
| Greater than 4, but 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% |
Building Control will select the dwellings to be tested. |
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Who should perform the tests?
Testing is required to be carried out by an ATTMA member (Air Tightness Testing and Measurement Association) or similar qualified expert. A copy of the results is then to be sent to the local authority.
Sheffield Insulations can arrange for air tightness tests to be carried out by our sister company. Their experienced technicians are highly trained and assessed to carry out air tightness tests to the standards and requirements set out by the BINDT (British Institute of Non Destructive Testing and ATTMA.) All our technicians are BINDT registered, so you can be sure of their competence. |
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Thermal Bridging
Thermal bridging, leading to poor airtightness and loss of heat, occurs where there is a break in the continuity of the insulation layer applied around the building envelope so allowing ingress of cold air into the building and leading to a significant loss of heat. The envelope of the building consists of exposed elements, of external walls, floors and roofing.
The insulation must be continuous over the whole building envelope to ensure air tightness.
Further information on Thermal Bridging is available in the Sheffield Insulations Part L Solutions Guide
For further information, or to arrange an Air Tightness test please contact us
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