Im familiar with standard foundation construction, as I design houses and produce loads of foundation plans and details. But thats for typical site built construction. I had no idea that "mobile homes" just used soil anchors. Thats wild. But I guess it makes sense if you have essentially zero foundation.
I have worked with factory built modules. At the high end its indistinguishable from site built if done well. Also nearly indistinguishable cost wise, depending on where youre building. Overall though I think factory built will gain ground.
I'm old school: learned architectural drafting in High School in the days of T squares and 0.5 mm mechanical pencils, and later moved on to ink on Mylar (tm) at work with utility drawings. Now it's all CAD. Still have an architect's scale because the things are just so handy for floor plans, but haven't even seen magazines that were catalogs of house plans for decades.
Mobile homes are typically mounted on loose concrete block pillars without so much as mortar. Have helped underpin one with concrete blocks. When it looked like we'd have to go to a doublewide, looked into a conventional foundation with a crane to set them on it, and some kind of steel to attach the foundation bolts to the I-beam flange.
Have seen a crane used to set a modular home on conventional foundations back in the 1970s and assume it was on conventional bolts used in house construction.
Mobile homes are a "trip." Before 2000, there were three levels of construction, which I won't mention because I might have them backwards. But the lightest construction has no storm sheeting and the highest has regular storm sheeting and stronger brackets for rafter and ceiling joists and such and are for coastal areas. They also have to contend with weight due to being hauled down the highway. Sheetrock was usually a quarter of an inch thick; plumbing was flexible pipes; most had no access points to work on the plumbing at all. Eves were narrow because of highway lane widths, but in the 1990s saw one that had a room cranked into place that had wider eves. There was one brand that's probably not made anymore that one building inspector praised, but what I saw looking at them was garbage. For whatever reason, every one we looked at had a fabulous master bath, but no lives most of their lives in the bathroom (I hope).
Maybe worse was how the companies installed - and still do- central AC units, and heat strips for winter use. People buying the trailers assume they're heat pumps. They aren't. Electric resistance heat is the most expensive heat their is. When we were looking at mobile homes, learned that if we went with a heat pump, we'd have to buy it from a heating and cooling company and have them install it. And that's why some of the highest electrical usage we see is from mobile homes. Lack of room for insulation is part of it, but those heat strips in the winter really run up the power bills.
My old boss had an idea of a set selection of house plans and a factory to cut all the pieces before delivery to the site. Kind of like those old mail-order homes from Sears & Roebuck. He never went with his idea. Maybe someone is doing that now. Anyway, my old boss thought it might could cut down on labor costs.
