New Approved Document L Published

The Government has published the guidance documents relating to Part L of the Building Regulations for England and Wales for the Conservation of Fuel and Power. The Approved Documents (AD) L1A and L1Bwill apply to work on new dwellings and existing dwellings respectively from 1 October 2010. The guidance given in AD L1A for new dwellings permits U-values for windows and doors to be determined in accordance with both BR 443 and the European product standard EN 14351-1 for the first time.  The U-value required has been reduced to be no worse than 2.0 W/m2K. The guidance given in AD L1B for work on existing dwellings is that for all types of building work, be it replacement windows and doors, an extension or conversion,  windows should have a U-value no worse than 1.6 W/m2K or an Energy Rating of band C or better. Doors should have a U-value no worse than 1.8 W/m2K. However, where replacement windows are unable to meet these requirements because of a need to maintain the external appearance of the facade or the character of the building, they should meet the centre pane U-value of 1.2 W/m2K. There are some exemptions for some historic buildings and some conservatories or porches.  The guidance only applies to windows and doors where the whole product is replaced rather than repairs, such as replacing glazing units or a door leaf, although it does recommend complying in these circumstances if possible. BWF Technical Manager Kevin Underwood commented ‘There are no real surprises as far as the guidance for windows is concerned.  We’re pleased to see both whole window and centre pane U-values have been retained as methods of showing compliance.  However, the requirement for replacement doors is tight.’ Click here to read the Approved Document for new dwellings and here to read the Approved Document for existing dwellings in full.  The Approved Documents for buildings other than dwellings can be found on the Government’s Planning Portal.