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The Changes to Part L1B in Wales

Part L has been revised several times since the turn of the millennium, but this is a more momentous change as this is the first time Part L is being split in two: There will be one version to cover England and a separate version for Wales. If you’re involved in domestic conversions or extensions in Wales, there are a number of key changes worth noting. These go live for all developments which are submitted to Building Control from 31st July 2014.

The first change is to do with U-values. New, tougher targets are being brought in for any newly built element. This includes extensions and replacements, and are the same targets as those being brought in for newly-built dwellings:

- For heat loss floors, the U-Value is reduced from 0.22 to a maximum average of 0.18 - For heat loss walls, the U-Value is reduced from 0.28 to a maximum average of 0.21

- For roofs, the U-Value is reduced from 0.18 to a maximum average of 0.15

- For glazing, the U-Value remains at 1.60 for windows and roof-lights, and is being reduced to 1.60 (from 1.80) for doors.

If you are renovating an existing wall, floor or roof, then the U-Value targets do not change from the current set of regulations.

Extra Flexibility 

Also, there are a number of leniencies built into Part L1B which are also being carried into this new set of regulations. These allow a developer extra flexibility if renovating would cause issues to the people living in the house (for example, low head-heights or uneven floors). You may be able to argue against certain requirements of L1B if the changes are not ‘functionally or technically feasible’. As well as this, a new mandatory section is going live for extensions, called Consequential Improvements. This requires developers to upgrade parts of the existing house while completing work on the extension.

3 Rules to Follow...

There are three rules to follow:

1) If the existing house has empty cavity walls, fill them with insulation.

2) If the roof insulation is less than 200mm thick, increase it to at least 250mm.

3) If the hot water cylinder has none or poor levels of insulation, fit an additional jacket to reduce heat loss.

For small extensions (less than 10sqm), you only need to follow option 2 (roof insulation). If it can be shown that making these consequential improvement upgrades is not economically feasible, then you don’t have to do it. This can be shown by working out how much each upgrade would cost, and comparing to the expected fuel cost saving over the next 15 years (using SAP assessment tools).

In England, Consequential Improvements will not comply, and Part L1B U-Values are not changing from those published in the 2010 Regs. The full set of Welsh building regulations for Part L, including the new Elemental Recipe, are available from the Welsh Government website. For more details about Part L and how the changes may impact you, contact Energist UK on 08458 386 387. You can also follow us on Twitter @EnergistUK for regular updates or join the UK Building Regulations Network on LinkedIn.

Jon Ponting

Author: Jon Ponting

This article was published by Jon Ponting on 27.02.2014.