SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Hello, and thank you for your help. In 2006 we completed a remodel of our house. Half inch pipe is used throughout the house, and rather than replace it with three-quarter (as it is in the front yard from the main to the house), our contractor fitted copper to the rear of the house for backyard irrigation. He welded a threaded male piece onto that pipe. I am now preparing to install a sprinkler system in the backyard. I realize the limitations of pressure due to the half inch pipe, but I have no idea how to marry the male threaded copper to a female PVC? I would like to install a shut off valve as well a close to this connection as possible. We live in northern California where the winters are relatively mild, but we do have an occasional freeze. Thanks very much for any information you can pass along. Best regards, Jim