What you need to look out for
Under Building Regulations Approved Document (AD) L1A there is a mandatory requirement for air tightness testing to be carried out on new residential dwellings (houses and flats),
AD L1A sets out the criteria regarding the sample of dwellings to be tested, which depends on the size of the development, and the dwelling types. In addition, AD L1A provides the air tightness performance standards which the tested dwelling/s must comply with (or in most cases significantly improve upon).
The air tightness test is carried out towards the final stages of the development, and the results of the test are ultimately incorporated into the dwelling's as-built SAP calculation.
In order to achieve the required air tightness targets (and to avoid the risk of a failed test), we strongly recommend that early consideration is given to the air tightness of the dwelling/s. By working with our clients throughout both the design and construction stages, we can provide advice and guidance on the most feasible ways to avoid air leakage and achieve (and often improve upon) the required air tightness targets.
As the requirements of Building Regulations AD L1A of has become more stringent over the last decade, air leakage targets have increased thus decreasing the margin for error. Each of the above air leakage paths can be avoided through good design and workmanship. It is essential that trades involved in the project such as plumbers, electricians and dryliners have a good understanding of the air leakage testing process and common pitfalls which can be avoided.