The smallest was only about 3m2 but was an extension nonetheless. Largest to date was just under 100m2 and consisted of ground floor kitchen and dining room, utility room, cloak room and then on the first floor, new bathroom and an additional bedroom.
Re-creating the original style of the property there were bay windows to the dining and bedrooms and vaulted ceilings to the dining room. The use of bamboo in the bathroom allowed the feel of wood but with the practicality and durability of grass!
More commonly, single storey kitchen / dining room extensions with either flat polymer membrane and occasionally felt roofs or pitched slate or tile roofs. Some flat ones built with solar panels in mind so that the owner can safely load up the roof with energy saving collectors at a later time.