Planning Permission for a Garden Room Based on Irish planning regulations, at the time of writing this article, in most cases a garden room will not require planning permission because it is usually falls into the category of class 3 exempted development (s.i. no.600/2001). Construction of a garden room to the rear of the house does not require planning permission if: • the area of garden room does not exceed 25 square metres; • the garden room is not reducing the amount of p