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Shipping dulls prefab's labor savings
Labor costs and distance
Using RSMeans City Cost Index values for installation costs as a proxy for construction labor costs, there is roughly a 2x difference between the 10th percentile city and the 90th. Prefab factories mostly sit within about 500 miles of their sites, roughly the farthest a truck can drive in a single day.
Autovol and Stack
Autovol builds its modules in Nampa, Idaho, and ships them hundreds of miles past that limit to Los Angeles and the Bay Area. Stack Modular builds its modules in China and carries them to West Coast projects on bulk carriers.
What the savings look like
Autovol claims its costs beat conventional construction in the high-cost California metros it serves. Stack Modular, despite its low-cost Chinese labor, claims cost certainty and a reduced schedule rather than lower hard costs. Volumetric Building Companies finds that modular works best when the labor cost gap between factory and site is large, and that savings are typically 5 to 10 percent and often don't appear at all.
Why is a day's truck drive the limit?
US federal hours-of-service rules cap truck drivers at 11 hours of driving within a 14-hour window. That comes after 10 consecutive hours off duty. At highway speeds, 11 hours covers several hundred miles. Beyond that distance, a delivery needs a second driver or an overnight stop, which adds to the cost.
Why do oversize loads cost more to haul?
The standard legal maximum width for a truck load on US highways is 8 feet 6 inches. Modules wider than that need permits, escort vehicles, and approved routes, and many states restrict them to daylight travel. Each state along the way issues its own permit. Wide loads also cannot use some bridges and narrow roads.
Why does modular building promise a shorter schedule?
Foundation and site work can proceed while the modules are being built in a factory, so two steps that normally run one after another overlap. Factory work also continues regardless of weather, which often delays work on a site. Quality checks happen at fixed stations on the line. Time saved on a project reduces the interest owed on construction loans.
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