Design Architecture Yes in My Backyard: Yves Behar and Plant Prefab Introduce ADUs By Lloyd Alter Design Editor University of Toronto Lloyd Alter is Design Editor for Treehugger and teaches Sustainable Design at Ryerson University in Toronto. our editorial process Facebook Facebook Twitter Twitter Lloyd Alter Updated November 15, 2018 ©. Fuseproject Share Twitter Pinterest Email Design Tiny Homes Architecture Interior Design Green Design Urban Design Little backyard houses are big in California now. Two TreeHugger favourites are working together to build Accessory Dwelling Units (ADUs) or back lane/ yard housing: Steve Glenn of LivingHomes and Plant Prefab, and designer Yves Béhar of Fuseproject. Béhar explains that Governor Jerry Brown passed a law recently making ADUs legal in California, making it possible for people to have "fully functional building in their backyards." Béhar is interviewed by Tim McKeough of the New York Times about the project, and explains the advantage of prefab: The reason prefabs make so much sense in the A.D.U. context is that the added construction is easy on neighborhoods and neighbors. It can take two, three years to build something, with all the noise and visual pollution. And wasted materials that come with that. But with the YB1, it takes about a month to build it in a factory and a day to install. It comes prewired with all your electrical, HVAC, appliances — everything is ready to go. Prefabs make it so much more accessible for people to add housing stock, and it’s so much cleaner. © Fuseproject The units sit on our favourite footings, helical piles, which are easy and fast to install and cause the least amount of disruption. The cost for the first units is about $ 280,000 for 625 square feet. To save you searching for your HP 15C that's $448 per square foot. And in the comments, the usual objections come up: "$480 per sq ft is $200 higher than a conventionally built custom home with nice finishes. Good idea, but it appears there is a high premium for these ADU's." Or, "Yet another toy for the rich with no practical basis in reality for the majority of people, and only those who live in the sunbelt and in wealthy enclaves." Or, "This is beautiful and definitely solving a problem... for people with money. Not sure how it helps homelessness or people with less money." © Fuseproject The commenters miss a couple of fundamental points. The price is not that high, and is in fact in line with many tiny houses. It costs more to build small; you need all the expensive stuff, the bathroom and kitchen and services that a big house has; you have everything but the volume. In fact, I suspect the final price after services are connected to the house or the street will be higher.If you look at the Vancouver experience with back lane houses, many of them are built for family members, for kids who will never be able to afford a house of their own in the current market. So a homeowner borrows against their equity and gives their kid or their mom a place to live that carries for about $1,200 a month at current rates.Of course, this is not addressing the problem of homelessness. As I noted in a discussion of Vancouver, "Laneway houses are a way of increasing housing supply, but they are certainly no answer to the affordable housing crisis in Vancouver or anywhere." But they are still creating lots of relatively affordable units.I have a couple of minor concerns, the main one being that modular isn't always suitable for backyards without driveways, and Behar says the houses are designed on a four foot module, which seems awfully big for small houses on constrained sites where one is often fighting for inches. But Steve Glenn of Living Homes has been in the modern prefab business longer than anyone and he knows all this. I look forward to this team dropping a lot of these.