Question on curbing. My backyard is all dirt at the moment. I am having trees planted next week and am going to have a section enclosed with concrete curbing for grass. My question is do I trench and lay my sprinklers first then have the curbing put around the outside of the sprinklers or do I have the curbing done then try to trench under the curbing to install the sprinklers? I don't know how close those curbing machines can get to the sprinklers to leave little to no gap behind them.