It depends on the size and type of extension. Small porches or flat roof extensions are very reasonably priced. More substantial two storey extensions can be expensive. In general, the price is roughly proportional to the amount of space you add to your home.
Hawes
Hawes is a small market community as well as civil parish in Upper Wensleydale in the Richmondshire district of North Yorkshire, England, that was approved its market charter in 1699. Historically in the North Riding of Yorkshire, Hawes lies ahead of Wensleydale in the Yorkshire Dales; the River Ure runs to the north of the community and also is considered among the honeypot visitor attractions of the Yorkshire Dales National Park. It is referred to as the residence to the Yorkshire Wensleydale Cheese. The population in 2011 was 887; the approximated population in 2016 was 893. The parish of Hawes also includes the adjoining district of Gayle. The population of the full church was 1,137 in 2011 and also was approximated at 1,138 in 2016. Hawes is 31.2 miles (50.2 kilometres) west of the county town of Northallerton. The Wensleydale Creamery is a major manufacturer of Yorkshire Wensleydale cheese. Defined by Reader's Digest as The Village That Refused to Die, Hawes has an extremely active non-profit community group that looks for financing and uses the cash to re-open maintain community amenities that were closing.