Adding onto existing sprinkler system HELP!!

Irrigation systems, sprinklers & other watering topics
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Adding onto existing sprinkler system HELP!!

Post by Llane3 »


I'm trying to get some help on finishing up my backyard landscaping.

I just moved into a new house and was the front yard was landscaped by the builder. I'm currently working on the backyard, and am about ready for the sprinkler system and sod, my problem is, I don't have much experience with a sprinkler system. Here's the scenario: I put a gravel border around my yard, and am separating that and the grass with some edging. I currently have the main sprinkler line (PVP) coming up to the back corner of the house, on the other corner of the house I have the wiring for the sprinkler system. My rainbird system has the front yard already hooked up to it and I'm thinking all I need is to add 6 sprinklers to the back and then sod over the fertilizer and dirt (I was told I shouldn't need topsoil because of the existing sand/dirt).

Here's a diagram of the backyard, and a second of what I'm thinking I should do for the sprinkler layout. Can I get some input on if I'm going in the right direction with this? My biggest question is how to connect the existing wiring to the new sprinklers and how to get it all set up on my current rainbird system. Is 6 sprinklers good? Are there specific sprinklers I should buy? Keep the same thickness of PVC? How low should I keep the PVC in the ground? I don't know how thick the sod is, but how low/high should the sprinkler heads be to the top of the dirt before installing the sod?

I really appreciate all the help on this. I've decided to make this a DIY project because I got 2 quotes, one was $7,500 and the other was $4,500. I think I can get all the materials for about $1000, so i'd rather save the money and spend a weekend doing this.

(The rainbird system is on the left side of the house, attached to the garage wall)
(The in the ground sprinkler box is on the right side of the house, shown in the pictures)


Last edited by Llane3 on Fri Nov 15, 2019 12:46 pm, edited 1 time in total.

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Re: Adding onto existing sprinkler system HELP!!

Post by corneliani »

Does the "main sprinkler line" run through the sprinkler box? Specifically, is it connected to a valve? If so the builder may have prepped a backyard zone already for you, and if so the wiring should already be done (note that the wiring goes TO THE VALVES and NOT to the sprinklers, as your post reads). Also, where does the sprinkler wire on your sketch come from, is that already ran & connected to your controller? Or is that something you're planning on running.

Lots of questions... to get a final design you'll need to do a water pressure & flow test first.

As for the other questions:
- overall conceptual design look good. I would personally opt for the heads to be placed in the gravel area vs lawn, allowing you for unobstructed future aeration and mowing, not to mention overall cleanness.
- sprinkler spacing is acceptable, but you'll have to choose between overspraying onto the gravel (on the 20' side) or not reaching the center sprinkler head (as they're spaced at 25').
- the number of sprinkler heads on 1 zone depends heavily on how much water is coming out of that pipe. Imagine if you have all of your bathtubs running at once... sooner or later you'll notice the pressure & flow is decreased due to it being shared amongst all the tubs. Same idea with sprinklers, except that if you don't have the pressure & flow your sprinklers won't reach their intended distance.
- the pipe sizing is also related to your flow rate.. but generally you'll see min 1" on the main and 3/4" on the laterals.
- the pipe depth is typically determined by your frost line (how deep your ground freezes). Here in Atlanta we can put it as low as 6" but generally speaking a good quality install will try for 12"+ (mainly to protect it from future impact, etc). Again, this is area specific.
- depth of head on bermudagrass is typically at the same height as the dirt (just the tip on top).
Last edited by corneliani on Fri Nov 15, 2019 2:38 pm, edited 1 time in total.

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