which to place first - patio or channel drainage?

Hi all, I've built a garden retaining wall (quite proud of the result too, being a novice!) and am now going to place a patio between the house and the bottom of the wall. The patio will 'fall' away from the house so I'll have channel drainage running along the base of the wall.
My question is should I lay the patio first then the channel drain, or set the drain first then the patio? With the patio running the width of the house and 5m across, I worry about the two meeting at the right height - especially with the drain needing to fall to each end!
Thanks for any advice

You always set your drains first.

You need to calculate the falls needed and lay your paving to taut stringlines or using a long straight edge, there should be no 'hope they meet' if you are careful and double check everything.

I would advise a fall somewhere around 1:50. you can go slightly less than this dependig on your paving choice and your skill level.

For aco channels you can make it easier on yourself and put them in pretty much level, water will find its way out no problem as long as the channel doesn't fall the wrong way.

Many thanks r896neo (and not the first time you've helped me - much appreciated)
Unfortunately I've already purchased the channel drainage and it isn't aco as far as I can tell (so cheap I don't think the manufacturer has even put their name to it!)
Still, what could possibly go wrong... [/code]

Aco is a bit like hoover, its a trade name that has become the normal name for channel drainage. most of them have their flaws in one way or another.

You may need an accessory kit with it which will provide the end caps and the outfall connection. May have been supplied with it depending on mftr.