Making the area drain in the right direction is the most important. If you need to dig in a 4 inch perforated drain tile off the area where the pad will drain then do so at this point. Getting the sub soil that is clay to drain in the right direction is crucial.

To make digging the clay easier you may consider renting a thatcher. Lawn thatchers are great for leveling dirt. I wouldnt tell the rental agency this but many professionals use thatchers to grade, lol. Not sure how well it will work on clay.

After grade is established the more gravel base you have the better. 6 inches is good 8 inches is better etc. Just simple crush isnt as good as 3/4 chip or washed gravel. The better it drains the better the pad. All those fines in simple crush will retain water and encourage heaving. After the chip you put in 1 or 2 inches of sand to lay the pavers on. If you arent sure how to put in screet pipes on stakes now is the time to ask.

If your roof drains a lot of water in this direction you may need rain gutters. They can tie into your 4 inch perforated drain tile to make a single trench in a safe direction.

Hope this helps, Good luck.

"2) I've heard you need AT MINIMUM 6" of "road crush gravel", tamped down to 3". I have also heard 8" tamped to 4". Which is true? The pavers we are using are about 3" thick."

I see you live in Canada. The answer to your question depends on just where in Canada you live. Here in BC, we need no crush layer at all.

Don't think just about levelling/grading but about curvature/channelling. Just as a road surface is somewhat mounded to drain water off to the sides, so can your patio be, or you can put in a swale to direct the water where you want. From your idea of eaves along the fence I presume you have a safe place to run it to, but I'm not clear on what that would be, or why you think it's safe.

Your question about whether the flowerbeds will be an adequate "sponge" depends also on what kind of rainfall your area gets, and how your property is situated relative to your neighbours.

The plan looks lovely, in any event.

KarinL

"If you arent sure how to put in screet pipes on stakes now is the time to ask."

Fire away :)

Well, to determine the final grade of your pavers on sand you will need to establish a level to grade the sand to. A string line or 8 foot level can work or you can rent a transit depending on how accurate you want to be.

You determine the grade of the BASE of your pavers including drainage and you pound 2x2 stakes or similar supports into the ground at that level. The stakes can be 4 feet apart and need to cover the entire area in a grid.

On top of the stakes you lay steel pipes or other rigid material in appropriate lengths. For your job 8 feet is fine. You only do one section at a time so 2 pipes are enough.
You put these pipes down on top of the stakes so they are parallel. Now you have 2 parallel pipes roughly 6 feet apart laying on stakes. You put sand in around them till they are barely showing.

Place a good straight 2x4 across the top edge of your 2 pipes and pull the sand down the pipes into a level grade. Use a sawing motion as you slide the 2x4 along your pipes.
This ussualy takes one person on each end of the 2x4. This is Screeting.

Once you have a perfectly level pad of sand around the pipes you pull them up and move them to the next set of stakes. Often you will only move one pipe to the next location and leap frog around the area in this fashion.

The depression left after you move the pipe is filled in with more sand and carefully screeted with a short board.

Now you can lay your pavers on the perfectly graded sand. Once you have paved in an area you fill and screet the next closest area. In this fashion you gain a perfect grade over the intire area which is established by the height at which you place the stakes.

For winding paths a person can use PVC pipe to sit on the stakes and bend to follow the curves. Sometimes it in necessary to put nails or screws in the stakes to hold the pipes in place.

Obviously the stakes get barried in the long run.

Of course paver edging is used around the perimeter to keep the pavers in place. Once the pavers are placed you put sand over them and use a vibrating plate compactor to seat and level them. Sweep it off, and wash it and your done.

This is called screeding where I live. Maybe a regional variation?

I promised myself I wouldn't but the above advice is trouble for you as a DIYer. ty has been doing it his way with some success I imagine but this enquiry is all over the place with his advice and the idea that you can compact compact crusher run by 100% which will not happen. I think you will find the people who make the Roman pavers helpful so you should visit their website the ICPI also has a website and is loaded with information. I am not prepared to give a lecture on the subject as it is adequately covered elsewhere.