Hi Andy
Hope you're well and busy!!!
There are other factors possibly - Is the work to be done at night?. Is it a residential area - will there be noise restrictions.
If the work is to be carried out day or night what is the pedestrian footfall like?
Are you using pressure washers or dry steam?
Just done a store front in Balham over a couple of evenings and one very full night. In places there was 50 pieces of chewing gum per foot square. It was a residential area with medium footfall and serious noise restrictions.
All made the works take longer than they should have done!!!. Pricing is spot on!!!!!
Rob