One of the most popular ways of expanding a home is to add a side extension to the property. It can be a single storey side extension or can be a double storey depending on various factors. A side extension can have a flat roof or pitched roof depending upon the design of the original house .Depending on the size of the extension, the homeowner may apply for Planning permission.
If you live within any area that enjoys a statutory designation such as a conservation area or national park, do remember that it will not be possible to build a side extension without planning permission.