Building systems guide
Modular building systems, explained
Short answer
A modular building system builds finished 3D room modules in a factory and sets them on a foundation. A panelized system builds flat wall panels, floor cassettes and roof panels instead. Both are prefab, and both move work off site. Manufactured homes are a separate category: built to the federal HUD Code, traditionally on a steel chassis. Module Building Systems is a panelized builder, not a modular or manufactured home builder.
The systems
The main offsite building systems
Every system moves work into a factory. They differ in what ships, how it travels and how much of the building is finished before it arrives.
Volumetric modular
Finished 3D boxes with walls, floors and often interior finishes, built in a factory and craned onto a foundation. Module size is set by what can travel on the road.
Manufactured (HUD Code) homes
Homes built to the federal HUD Code instead of local building codes, traditionally on a permanent steel chassis used to move them. Often called mobile homes, and often mixed up with modular.
Open wall panels
MBS builds thisFramed walls with coordinated openings, built in a factory. Sheathing, insulation and finishes happen on site.
Closed wall panels
MBS builds thisPanels leave the factory insulated and closed, with windows, doors, cladding and MEP rough-in installed.
Floor cassettes and roof panels
MBS builds thisPre-framed floor and roof sections with decking where specified, built to match the wall panels.
Other offsite systems
Structural insulated panels (SIPs), precast concrete and steel framing are also built off site. MBS works in wood framing.
Floor cassettes ready to ship from our St. Louis line
Choosing a system
Six questions to ask any modular or panel supplier
- 01
How does it ship?
Modules are often oversize loads that need permits and escorts. MBS panels ship on standard flatbed and step-deck trucks.
- 02
Can it follow my drawings?
A module is limited by its shipping width and height. Panels are cut to your drawings, with no fixed box size.
- 03
Who inspects it?
Manufactured homes follow the federal HUD Code. Modular units often go through a state program and carry a seal. In Missouri, MBS panels are inspected as conventional wood framing. We confirm the pathway for your state before scheduling.
- 04
How will my lender see it?
Fannie Mae's Selling Guide (B2-3-02) says panelized housing "is not considered manufactured housing." Ask your lender early how it funds factory-built components.
- 05
What is fixed in the price?
MBS fixes the factory panel price from contract through delivery, with freight within 1,000 miles included.
- 06
Who sets it?
Your crew can set MBS panels, or MBS coordinates installation with your GC.
What is a modular building system?
A modular building system builds a structure as finished 3D modules in a factory. The modules ship to the site and are set on a foundation, usually by crane. Module size is limited by what can travel on the road.
Is prefab the same as modular?
No. Prefab covers any building made partly in a factory. Modular is one prefab method. Panelized is another: walls, floors and roofs ship flat and form a conventional wood-framed building on site.
What is offsite construction?
Offsite construction moves building work from the job site into a factory. Modular, panelized and precast are all offsite methods. MBS builds wood-framed wall panels, floor cassettes and roof panels in St. Louis.
What is panelized construction?
Panelized construction is conventional wood framing built in a factory. MBS cuts wall panels and floor cassettes on CNC equipment in St. Louis, closes them with insulation, windows, doors, cladding and MEP rough-in, ships them flat on standard trucks and sets them on your foundation. The finished building is stick-built, not a modular box or a manufactured home.
Is MBS a modular builder?
No. Modular builders ship finished 3D boxes. MBS ships flat wall panels and floor cassettes that form a conventional wood-framed building on site. There is no chassis, no HUD-code unit and no volumetric box, and no wide-load transport.
Is a modular home the same as a manufactured home?
No, though many people use the words the same way. Manufactured homes are built to the federal HUD Code, traditionally on a permanent steel chassis used to move them. Modular and panelized buildings are built to the state and local building codes that govern site-built construction, and they sit on permanent foundations. MBS builds panelized: no chassis, no HUD-code unit, no volumetric box.
Start a project
Send your plans. Get a fixed factory price.
Permit-ready drawings and a site address are all we need. Your estimate is valid for 30 days and includes freight within 1,000 miles.