As part of the government’s pursuit for greater energy efficiency and the conservation of fuel and power, Building Regulations April 2006 part L1A stipulates all new dwellings must demonstrate they are airtight to an agreed standard.    In order to comply with the regulations, all newly built homes must undergo a mandatory Air permeability test prior to occupation and certification to the required ATTMA ‘TS1’ standard. Tests must be carried out by an approved tester registered with the British Institute of Non-Destructive Testing (BINDT) It is beneficial to the main building Contractor for the Test to be carried out as early as possible, so lessons can be learned and adjustments to design and/or site procedures made before the majority of the dwellings are built. The specific dwellings will be selected by the Building Control Officer or Accredited Inspector. At least one dwelling of every type within a residential development must undergo Air Pressure Testing. This is to ensure the assumed level of air permeability used in the SAP calculations has been achieved. The maximum level of air permeability on developments with more than two dwellings is 10 m³/m².h at 50Pa.Various generic forms of dwelling are considered as separate discreet types. Examples include:

o Detached                       o Semi detached
o End-terrace                   o Mid-terrace
o Ground-floor flat           o Mid-floor flat         o Top-floor flat  

The number of storeys will also define different dwelling types, i.e. 1, 2, 3, etc. For dwellings to be considered to be of the same type:
• They must contain the same construction details for each of the main elements, i.e. walls, floors and roofs.

• They must have similar floor areas. Small variations in gross floor area do not constitute a different dwelling type. For the purposes of this Technical Standard the difference in gross floor area between the largest and smallest within a dwelling type should be no greater than 15%. 

Number of dwelling type                         Number of tests to be carried out per dwelling type

3 or less                                                               one test of each dwelling type

4 to 40                                                                   two tests of each dwelling type

40 or more                                                           At least 5% of the dwelling type, unless the first 5 units of the tested type achieve the design air permeability.

How we can help

We are able to work closely with the construction team to assess suitable times for testing – ensuring minimal disturbance on site. Information supplied before hand means that we can calculate all necessary information such as building area envelope and volume, and all on site measures such as sealing temporary openings are carried out efficiently to ensure accurate readings with minimal disruption to your build. We offer a competitive pricing structure which includes:Testing by a BINDT registered specialist. Tests carried out within 72 hours of appointment if required. Test report including unique BINDT certificate issued. Report identifying leakage points, should a dwelling fail a test. 

Site Inspections & Reports 

The provision of an air-tightness expert to inspect air-barrier details within ‘work in progress’ plots on site can be of considerable assistance to hard-pressed Site Managers. Not only can potential problem areas be identified and addressed early in the programme, our detailed, illustrated reports provide invaluable third-party evidence to put before potentially culpable sub-contractors.