[TomCrowther]

I cleaned a large cobbled drive last week. Quoted same as I would for block paving, big mistake. The cobbles were set in stone and had gaps of around twenty mm between each block and the stone setting was around forty mm deep.
The sand and moss became like quick sand, very slushy stuff, stop start the whole day. My lad said he felt like he was working in a farm for the day. Nightmare. Then it took a skip load of new sand brushed in 
Moral if the story, look at the job carefully before quoting.

[BDCS]

I use sharp sand on tumbled blocks. Start at the bottom next time and the sand then flows down and settles in the gaps already cleaned and always use the fsc to clean.

[H20cleaning]

i did the exact same when i first start... i quoted a drive  and the owner rang straight back up and asked for the back to be done aswell for the same price!
did the job and it took over double the time i first thought:| when i had finished the owner laughed and said '' i had a quote of over double your price.... i bet you wish you had never started?''
but its a learning curve, so now i ALWAYS look carefully