shawn
A house that size, to include external glass as well, leaving the property gleaming, i would charge £350-£450, it is a lot of work!
I quoted on a house like this a few months back , told the lady I 'm not interested , she asked what sort of price i would be lookin at anyway so I said £300 - she fell to the floor
I passed this job onto a friend - he gave her a quote for £500
--- he didn't want it as well - may be the same woman haha