Also to add another view to the topic, when a developer plans to build a development, it makes much better sense for him and you to know how much you charge, if as Tim says he charges a set price for each room, those rooms are going to be different sizes in each property, for example a kitchen in a 650 sq ft one bed apartment is going to be tiny, but a kitchen in a 5 bed house is going to be considerably larger, a hall in the apartment is going to differ in size to the hall in the larger property and so on…
What I’m trying to say is: Whatever happens you need to know the size of each room, this is why the norm for new build cleans is by the sq ft, but as I have stressed it’s the spec of the properties that makes you decide if its, 12p or 25p per sq ft, we’ve just completed a 8500 sq ft property of very high specification, the charge for the initial clean (although completed over 2 weeks in stages) was £2100
Just to add: it was on the news recently that the government have stated that there is the need for 5 million more new properties in the uk in the future.