Three Kinds of Modular Company — And What Each One Actually Sells
The Short Version
Factories sell approved boxes. Engineering firms sell sealed site design. Design-build companies sell a single contract over both — which is worth exactly what its scope split is worth. Confusing the three is the most expensive vocabulary mistake in modular buying.
The factory: engineering that ends at its own wall
A manufacturer's engineering is real engineering — structure, systems, and finishes designed once, approved under the state program, and repeated per unit. Its boundary is equally real: the approval covers the box as shipped, not the ground it lands on, not the seams that join it, not the permits that receive it. Buy a factory for the quality of its box and the standing of its label; never mistake its brochure for a site plan.
The engineering firm: the half nobody photographs
The site engineering firm designs what the brochure gestures at: foundations from your soils and the plant's published loads, anchorage, utility laterals, marriage-line connections, and every site-built element — sealed by licensees of your state and permitted at your counter. It sells no boxes and hosts no plant tours. Its product is the second building, and a purchase without it is half a purchase.
The design-build company: one contract, two paper trails
Design-build is a contract shape, not an approval. Done well, it coordinates the factory scope and the site scope under one signature — and still produces both paper trails: the program label for the box and the sealed site set for everything outside it. Done badly, it uses the single contract to blur the boundary until the missing half surfaces at set day. The split document, requested before signing, tells you which kind you are hiring.
