I learn new things about the prefab business every day. Altamont Homes is a builder of modular homes throughout the West. The company had representatives at West Coast Green. Also at their booth was a representative from Details, a manufacturer of modular homes.

In the time I've been reading and writing about prefab housing, I haven't fully understood the relationship between those two entities until the relationship was explained to me by Craig Rosenberg of Details.

Basically it works like this: the homeowner goes to a "builder" (in this case, Altamont) and wants to build a house. Altamont shares a number of design options with the homeowner, ranging from small, inexpensive homes, to larger and more finely detailed homes. The home designs they are sharing are sourced from a number of "manufacturers" around the country (in this case Details is one of many that Altamont buys from).

Altamont is responsible for interacting with you, completing site work, securing permits (sometimes that falls to the homeowner), setting the home and completing site work. Details is responsible for the modules that are shipped to your site. The way that Craig Rosenberg from Details explained it to me:

"Some manufacturers supply products like doors or faucets; it just happens in our case that the product we supply is the entire home."

Details designs the homes that they offer to different builders, whether Altamont or another builder. The arrangement allows Altamont to offer a wide range of product choices to their customers. For instance, the Details models are all LEED-certified and highly energy-efficient; they generally end up costing ~$275/sf installed. Altamont offers other, non-LEED options from other manufacturers for less than half that cost.

The key point is that the builder and manufacturer are two different entities, with two different specialities:
Builders: expertise in site work, permit process, setting and finishing home
Manufacturers: expertise in designing and manufacturing the home modules