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Summary of Main Regulation Changes 2006 – 2010

Airtightness testing remains a legal requirement for completion testing of the majority of non domestic properties, and an increased sample size of domestic dwellings.

From 1st October 2010, the testing standard ATTMA TS1 2006 has been revised into two documents ATTMA TSL1 and ATTMA TSL2 which apply to Building Regulations ADL1 and ADL2 respectively. The majority of changes apply to the L1a document for new dwellings.

On each L1a scheme, a test is required on three units or 50% of a dwelling type – whichever is less. Dwelling “types” have been further defined to assist in formulating testing regimes.

The target carbon dioxide emissions rate for new dwellings (TER) has been improved by 25%. As a way of achieving these lower emissions, designers will opt for lower design air permeability targets

When a unit is tested, the result applies to that unit only. For units of a similar “type” that have not been tested, the assessed air permeability is the average of the similar tested units, increased by a margin of +2.

The worst acceptable standard remains the same at no greater than 10m3(h.m2) @ 50Pa. On sites with multiple plots of similar type, allowing that untested units will have +2 added, test results of similar “type” will need to be below 8 to reach the minimum standard.

The main change to the test procedure is that it is now permitted to apply temporary seals to all natural ventilation units and trickle vents.

Schemes that commenced on site before 1st October 2010 continue to use the 2006 standards. Schemes registered prior to 1st October 2010, which commence before October 2011 may also use the 2006 standard.

“The specific dwellings making up the test sample should be selected by the Building Control Body (BCB) in consultation with the pressure tester”