A day
What sort of clean do they require ?
What is the wood - hard wood, soft wood ?
Any previous decking oil or worse wood stain on it ??
What's the actual sizes of the decking - the paths are no problem around £120
For the decking you need to know everything and find out if they want it re oiled if it's had oil or stain on it then you need to follow a process it's not a matter of just washing it.
If you want the very best advice for decking work get in touch with Roger Oakley - he walked me through some early decking jobs - such a shame he no longer uses this forum
Darran