Ever wondered how long it would take to build an accessory dwelling unit, or ADU, in your backyard? In the case of Alvaro “Al” and Nenette Alcazar, a retired couple, who downsized from a six-bedroom home in New Orleans to a one-bedroom ADU in Los Angeles, it took just 3½ months. “We went on vacation to the Philippines in November, right as they were getting started on construction,” Al says of the ADU his son Jay Alcazar and his partner Andy Campbell added behind their home in Harbor Gateway. “When we returned in March of this year, the house was ready for us.” The Alcazars were surprised by the rapid completion of their new 570-square-foot modular home by Gardena-based Cover. By the time construction was finished, they hadn’t yet listed their New Orleans home, where they lived for 54 years while raising their two sons. Andy Campbell, seated left, and his partner Jay Alcazar’s home is reflected in the windows of the ADU where Alcazar’s parents Al and Nenette Alcazar, standing, now reside. Jay Alcazar …