Wondering whether to build on a traditional Foundation or a Trailer? To build on a traditional foundation, a building permit is required which is often a lengthy and complex process depending on the location. In most California cities, the process of drawing plans and obtaining a permit typically takes about 6 months. It may not even be possible to get a permit for an additional space depending on your setbacks and other city requirements. After the permit is approved, a contractor will need to be hired to get utilities to the building and build the foundation. Building a small backyard unit on a foundation, whether it’s 100% site build or a prefab unit on a foundation, costs anywhere from about $35k to $60k with permitting. And, of course, if it’s on a foundation, it cannot be moved. Our buildings on wheels are manufactured in our RVIA-certified factory and built to RV codes so they don’t require a building permit. They can legally be parked anywhere an RV can be parked. They can be fully self-contained so you don’t need any external utilities. Our buildings on wheels can be delivered in less than 3 months. We recommend building a patio and planters around the perimeter if you're concerned about the aesthetics of the trailer and wheels. If you're still interested in building on a foundation, as architects we’re happy to assist you.