Recently you answered a reader’s question about planning rules for building a garden shed. Would the same rules apply if you wanted to raise the roof of an attached garage by a few feet?
Different set of rules. Where extensions are concerned, the main planning requirements relate to the size of the house as originally built, or as it was in 1948 if it was built before then. Generally speaking there is no need for planning permission if the volume of the house has not been increased by more than 70 cubic metres or 15 per cent, up to a maximum of 115 cubic metres, whichever is the greater. There are similar rules about positioning, and height can be an issue particularly near boundaries, so speak to your local planning officer. Often the consent of the original builder is required on new estates.