Average home size in the UK is less than half that of the US: http://shrinkthatfootprint.com/how-big-is-a-house
US @ 77 sq meters per capita vs UK @ 33 sq meters per capita.
US @ 77 sq meters per capita vs UK @ 33 sq meters per capita.
We're a crowded island, we have small houses.
The UK has a lower population density the than both Belgium and Holland, both of which have larger average houses than the UK. So there has to be more to it than simply being 'crowded'.