The new Approved Documents L1A, L1B, L2A and L2B for Wales became effective on 31st July 2014.
The requirements are more onerous that those for England with lower CO2 emission targets; 8% improvement for dwellings and 20% improvement for non dwellings. The Welsh Part L1A is broadly similar to the English version however there is no Fabric Energy Efficiency Standard. Instead prescriptive elemental U-values are utilised as part of the fabric first approach. These much lower limiting U-values for dwellings, both new build and extensions, are as follows;
Floors 0.18 W/m2K.
External Walls 0.21 W/m2K.
Party Walls 0.20 W/m2K.
Roofs 0.15 W/m2K.
The documents can be viewed and downloaded here.