Here is the picture that is worth 1000 words Since I am about to install the edging that you see in the backyard (area covered by the runs 1-4) I am considering installing the irrigation pipes in a channel formed by cutting a drain pipe in half along the longitudinal axis and then install the slabs that make the edge on top. The actual shape of the path will be pure rectangular I gave up on the zig-zags you see in the picture Do you see any issues raised by this design? The idea is to be able to reach the pipes easily without digging them out of the ground. This will add support to the slabs as well
It is not a common solution.
I like the idea that you are flexible, without digging: this is real gardening, not like most irrigation system where you should calculate precisely the amount of water in each pipe, and so you will have trouble if you want to do other experiments, or just a vegetable garden in some corner.
Disadvantages: much more prone to frost, so you should close and remove water on time, and personally I do not like the esthetics. I'm not sure if it will be also a place for animals to hides (snakes, spiders, etc.). I think that in few years the pipes and edging will be below lawn level. And I think there are other disadvantages: in fact your solution is seldom seen.
I would go to the different corners with a line, and from there I would irrigate the lawn, and pass the irrigation system just below soil, hidden by vegetation and bushes (so no real digging). On the other hand, it is your garden, and you have much better idea on what you will plant.
I'm not sure about pipe 5: if you want to irrigate your lawn, I see risk you "water" also your house.
My tip: check out Gardena website and catalogues. They sell expensive stuffs, but so they have good documentation (to get inspirations). And they are much more on DIY (and not as "requires professionals to install", so every few years you may change layout), and they base is to start from a spigot (your other question). Hunter instead has a lot of documentation about professional irrigation systems and designs (and how to do the detailed calculations), probably too complex (and too long to read all docs).
I m set on the orbit models as their controller seems to work with Google Assistant which is what I use for other things As far as #5 goes and actually every single line you see is designed to sprinkle the flowerbeds using directional jets limited for that small area with flower beds next to the sprinkler. The central area is grass and I do not plan to water it THese will be pop up sprinklers The layout is what is recommended in the Orbit manual on pag 11 and the following irrigationdepot.ca/boutique/PDF/Guide_Orbit_Installation_AN.pdf Jun 15, 2020 at 17:41
re:freezing, it will happen anyway unless I dig 4' deep into the ground so I could as well just hide the piles 1in under the slabs (to protect them from accidental digging) Jun 15, 2020 at 17:44
I don't get the aesthetics comment, what is bothering you? Everything will be hidden. If the path is bothering you that is not related to the irrigation system, I am about to put that one in anyway. I need it ass cutting grass is sending clips into the flower beds and the grass is growing into the flower bedes. The lawn mower will step on that edge with the wheels allowing me to cut near the edge from the lawn size Jun 15, 2020 at 17:48
freezing: it is about first freezing (you may be more diligent, but usually I wait first freeze to close external water supplies, but in my region first freeze is not so bad, and my setup permit me not to have problems on first freeze). Aesthetics: it is personal (and I'm more used on English style then Italian style of gardening). Jun 16, 2020 at 6:19
the edging is 6" wide and I am betting on the fact that it it will be half covered by grass and plants, leaving me enough spate to run the mower on it. it will look less intrusive or dominant when it mingles in the landscape. I did not aim for a certain style I just looked for solutions to problems that I had and I followed some general guide lines explained in a few books I browsed about this I will stop watering way ahead of the first freeze as Toronto is near lake Ontario and it rains well enough in October toronto.weatherstats.ca/charts/precipitation-monthly.html Jun 16, 2020 at 12:03