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ATTMA TS1 - Air Leakage Tests and Air Tightness Testing
in Sheffield, Manchester, Leeds and Nottingham


Blue Tree Acoustics provide BINDT certified Air Tightness Tests for new build dwellings across Yorkshire, Lancashire, Derbyshire and Nottinghamshire. We often test in Leeds, Manchester, Nottingham, Sheffield, York and the surrounding areas.


We give British Institute of Non-destructive Testing (BINDT) accredited testing for compliance of Approved Document L1A to the Building Regulations (ADL1A)


Air tightness tests are undertaken in accordance with Air Tightness Testing & Measurement Association (ATTMA) TS1 and Thermal performance of buildings - Determination of air permeability of buildings.





The Design Air Permeability is calculated in the DER (Dwelling CO2 Emissions Rate) evaluation at design stage by the SAP consultant (we can also offer SAP assessments).


The air tightness test measures the actual on site performance, and allows comparison with the stated design value.


The maximum design air permeability allowable under the building regulations is
10 m3/(h.m2) @50Pa.


In simple terms, this is a flow of air of 10 m3/hour for every m2 of dwelling envelope area, when the building is subject to a pressure of 50Pa.


The design air permeability may be lower than 10 m3/(h.m2), as a better standard may be required to offset lower performances in other energy performance areas such as insualtion performance.


From initial specification to on-site testing, our professional service provides clients with practical and cost effective solutions to achieve compliance with Part L1A of the Building Regulations.


Each actual air tightness test is a non-destructive test of building air leakage. Ventilation is excluded as the test is only concerned with areas of unintentional weakness such as gaps, cracks, incomplete seals.


The number of tests required varies depending on the size of the development and the number of dwelling types e.g. flats, terraced houses, semi-detached, detached etc. Small sites may require only one test. Larger sites may require many more tests.


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%


Dwelling types are: Detached; Semi-detached; Top floor flat; Mid floor flat; Ground floor flat; End terrace; Mid Terrace.

Also there should be subdivision in types so that there is a difference of no more than 15% in gross floor area between the smallest to largest in the group.

There should also be no more than 1 extra significant opening in the group.



Typically, a site will require between 2 and 10 tests.

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