Building extension - smaller garden - will it still be ok ?

[pasok1000]

If we build an extension, there would be 14 metres long garden left, 9 metres wide. Would extension still add value, despite decreasing the size of the garden? we are in London. Thank you/.

Our friends live in Putney and their garden is much smaller than that. Think it depends on your area. What is the norm locally?

Exactly, it all depends on how that compares with the houses nearby. In most of Putney, 14x9 is a very decent size. If you are in Guildford it's tiny.