This appendix outlines the provisions of TGD L - Dwellings 2011 insofar as they relate to the issue of air leakage (air permeability) only and refers to a backstop minimum performance level for air permeability of 7 m^7^hr/m^2^. However, subject to the transitional arrangements outlined, TGD L - Dwellings 2008 provides for a backstop minimum performance level for air permeability of 10 m^7^hr/m^2^: the lower the level, the more airtight the dwelling is.
The provisions of TGD L - Dwellings 2011 apply to works to new dwellings where the work commences or takes place, as the case may be, on or after 1st December 2011. The provisions of TGD L - Dwellings 2008 also cease to have effect from this date.
However, TGD L -- Dwellings 2008 may continue to be used in the case of dwellings where:
The work, material alteration, or the change of use commences or takes place, as the case may be, on or before 30th November 2011, OR
Planning approval or permission has been applied for on or before 30th November 2011, and substantial work has been completed by 30th November 2013.
“Substantial work has been completed” means that the structure of the external walls has been erected.
