There’s a lot of buzz about prefabricated homes, yet there’s a great deal of mystery about what prefab is. Many prefab buildings are pre-designed, and can be selected from a catalog, with several plan or façade alternatives to choose from. However, many are custom homes designed by an architect who then brings a pre-fab factory on board as part of the team. In many cases, the factory is also the General Contractor for the site work. The building is built in a factory very similar to how it would be built on-site, however it must be designed and constructed in modules that are small enough to transport on truck beds to the jobsite. Typically 10 to 14 feet wide and about 10-13 feet high, these modules join together once they are on site. If a volume ceiling is desired, modules can be stacked. These modular buildings can be any style, modern or traditional.
Factory-built buildings, even custom-designed ones, are usually less expensive than those that are site-built, because factories are located where labor is less expensive, and the construction process is more efficient and produces less waste. The transportation cost to the site, however, can offset the savings if the site is too far away.
Construction can be started earlier than with a site-built building, before the building permit approval, and can occur concurrently with the foundation and other site work. This is the reason why the total construction timeframe is faster than with a site-built building. The buildings are typically delivered to the site with the interiors already completely built out, including kitchens and bathrooms, so once at the site, they can be completed within a couple of weeks once the modules are delivered to the site.
In Los Angeles and Santa Barbara, a new site-constructed, an average house costs about $800 to $1,200 per square foot. The same home built in a factory might cost about 10% to 20% less with the added environmental benefits of being more eco-friendly even with the transport factored in. Remodels and additions are still better suited for on-site construction.
Multi-family residential buildings and commercial buildings can be prefabricated as well. I worked on several Bank of America branches that were prefabricated. This approach cut the construction schedule in half. These buildings were built in the factory in approximately six weeks while the site work, such as the foundation, paving, and utility hook-ups, were completed, They were then transported, erected, and finished within two additional weeks.
It may seem surprising that architects like the idea of a type of construction that requires less of our time, but we are, first and foremost, advocates for our clients, with a goal of achieving the best building possible for their dollar.
