On the 1st October 2010 changes to Part L of the Building Regulations come into effect. Part L deals with how well a building conserves fuel and power.
Whilst garden rooms don’t have to comply with Building Regulations unless they are over 15sqm and used for sleeping accommodation, many garden room suppliers do build their garden rooms to Building Regulation standards – which is a good thing!
Many garden room suppliers state that their buildings u-values (the rate at which heat is lost from a building – which Part L controls)out perform the Building Regulation standards for new buildings, which is a great selling point as it means the garden room will be comfortable to use all year round and cost effective to run.
So what is a u-value? It’s the measurement of the transmission of heat through an element such as a wall, roof or glass. In timber frame construction each element of the wall, such as the exterior cladding, sheathing, studwork, insulation and plasterboard will have a u-value and a garden room designer can work out the combined u-value of the wall, the lower the combined u-value the better performing the wall. U-values are expressed in W/m2 which equals the amount of heat in Watts that is lost per square meter of material. For example a wall with a u-value of 0.30W/m2 will lose 0.30 Watts for every m2 of surface area per degree of temperature difference between the inside and outside of the building.
The changes to Part L from 1st October 2010 lower the target u-values for walls, floors and roofs (remember the lower the u-value the better) meaning that garden rooms built to these new Building Regulation standards will perform even better. Below is a table of the existing u-values for a new build and the figures for 1st October 2010 onwards.
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As a customer it is important that you check the claimed u-values of a garden room with this table, especially if your supplier claims to exceed the Building Regulations for a new build house!