With space for housing becoming quite a problem in towns and cities, the infill method of extending out is very popular now.  It needs a really good interior designer to look at a space and be able to envisage it as a new kitchen or bathoom.  I know of a  young couple who live in a suburb of London.  They struggled like mad to get that first property and had to pay half a million for a very narrow, dark house that had been created out of the partitioning of two others.  They now have a baby and needed to build out themselves – into the only bit of space available.  Velux roof lights have made such a difference – they have a large bifold patio door out from the kitchen and the bathroom now resides in what was the store room.  Again additional ceiling mounted windows was the only means of getting any light in.  Fantastic space – is has just been sold for another few hundred thousand.