Air Leakage Testing Residential dwellings. L1A.

Residential Air Testing for houses, bungalows and flats.

Part L1A 2006 regulations: Relevant to Air Testing new residential dwellings whose Building Regulation applications were approved before October the 1st 2010.

Dwelling Type definition by L1A:

• A dwelling type is defined as a group of dwellings on a site having the same generic form
• A detached, semi-detached, end terrace or mid terrace house
• A ground-floor (inc. ground floor maisonette), mid-floor or top-floor flat (inc. top floor maisonette)
• Where the same construction methods are used for each of the main elements (walls, floors, roofs etc)
• Small variations in the floor area do not constitute a different dwelling type

Air testing regime using Approved Construction Details

• One of each dwelling type will need to be air tested.
• If any dwelling fails the air test then remedial work needs to be carried out and a further test carried out. A further dwelling also needs to be tested.
Air testing regime when not using Approved Construction Details
• 4 or less dwellings : air test one of each dwelling type.
• More than 4 but less than 40 dwellings: air test two of each dwelling type
• More than 40 dwellings: air test at least 5% of each dwelling type, unless the first 5 units tested pass the Design Air Permeability target. If so, the sampling can be reduced to 2%.
• If any dwelling fails the air test then remedial work needs to be carried out and a further air test carried out thereafter. A further dwelling of the same type also needs to be tested.

For Developments of two or less houses then a figure of 15 m³/hr/m² can be used for the DER Calculation and no air test is required. Alternatively if the same contractor has built the same design in the previous 12 months and can prove a compliant result then no air test is required. (DER: Design Emission Rate – normally the SAP calculations)

Should a residential air test fail, CPS's experienced staff will work with site to locate the air leakage paths and advise on sealing. Once the leakage paths are sealed by site we will carry out further air tests on the same day to try to obtain compliance.

Further visits however, on another day, will charged at the same fee again.

Part L1A 2010 regulations: Relevant to Air Testing new residential dwellings whose Building Regulation applications were approved after October 1st 2010.

• A dwelling type is defined as a group of dwellings on a site having the same generic form
• A detached, semi-detached, end terrace or mid terrace house
• A ground-floor (inc. ground floor maisonette), mid-floor or top-floor flat (inc. top floor maisonette)
• Where the same construction methods are used for each of the main elements (walls, floors, roofs etc)
• be of the same number of storeys
• be of the same design air permeability
• have similar adjacency to unheated spaces such as stairwells, integral garages etc
• have a similar (i.e. ±1) number of significant penetrations, i.e. for windows, doors, flues/chimneys, supply/exhaust terminals, waste water pipes
• have envelope areas that do not differ by more than 10%

Air Test Regime from 2010 Regulations

• On each development air testing should be carried out on three units of each dwelling type or 50 per cent of all instances of that dwelling type, whichever is the less.
• A block of flats should be treated as a separate development.
• The dwellings to be tested should be taken from the first completed batch of units of each dwelling type.
• Those dwellings selected for air testing should be selected so that about half of the scheduled tests, for each dwelling type, are carried out during construction of the first 25 per cent of each dwelling type.
• All air tests on dwellings in the sample should be reported including any test failure.
• In the event of an air test fail that dwelling must undergo remedial works so that it passes and another of the same dwelling type air tested.
• Where a dwelling of a type has not been air tested, the assessed air permeability is the average test result obtained from other dwellings of the same dwelling type on the development increased by a margin of +2.0m3/h/m2 at 50pa.
• In the event that the average of those air tested does not permit those not air tested to pass, then more must be air tested in an attempt to reduce the average.
• Conclusion, the number of dwellings requiring air testing will increase on each site.