The Chassis Rule Is Changing. The Structural System Should Too.

Published by TinyMod® Living | June 2026

There's a rule that has quietly shaped the manufactured housing industry for over 50 years. It doesn't get talked about in living rooms or on job sites very often, but it's had an enormous impact on what's possible in factory-built housing — and what isn't.

It's called the permanent chassis requirement.

And right now, it's changing.

What the Chassis Requirement Actually Does

Every HUD Code manufactured home has historically been required to be built on a permanent steel chassis — a heavy steel undercarriage that travels with the home and stays in place as its structural subfloor after installation. The chassis was originally conceived as the transportation system: drawbar, frame, running gear, lights. For single-story homes hauled down a two-lane highway in the 1970s, it made a certain kind of sense.

But the industry has evolved considerably since then. And the chassis requirement — especially on multi-story manufactured homes — has become less of a structural asset and more of a structural tax.

For multi-story manufactured homes, requiring a permanent chassis on upper floor sections adds between $4,800 and $6,700 per unit in production, transportation, and installation costs — costs that serve no practical purpose once the home arrives on site. Beyond the dollar figure, the permanent chassis requirement limits where staircases can be placed, creates wasted space between floors, and requires the lowest floor and foundation to be engineered to bear the full dead weight of an upper floor chassis that typically exceeds 2,500 pounds — driving up wood, concrete, and pier requirements across the whole project.

That's a lot of cost, complexity, and constraint for a component that stops doing anything useful the moment the home is set on its foundation.

What HUD Is Now Proposing

HUD published a proposed rule in the Federal Register on June 12, 2026 that would allow upper floor sections of manufactured homes to be transported and constructed without a permanent chassis. The rule targets multi-story manufactured housing specifically — and it's open for public comment through August 11, 2026.

This is a meaningful step. The proposed expanded definition would support multi-story construction of manufactured homes and empower manufacturers with greater flexibility to design and deliver homes that have historically been complicated, expensive, and logistically cumbersome to produce.

More than 20 million Americans currently live in manufactured homes, and the manufactured housing industry employs tens of thousands of workers nationwide. A change that reduces per-unit cost and unlocks design flexibility has real downstream impact at that scale.

For manufacturers who have been watching this regulatory conversation develop over the years, this proposed rule is a signal: the structural assumptions built into HUD Code housing since 1974 are finally being examined. And that opens a much bigger question — if the chassis requirement on upper floors is unnecessary, what does the right structural system for factory-built housing actually look like?

The Deeper Problem the Chassis Rule Exposes

The permanent chassis requirement is really a symptom of a broader design constraint that has shaped manufactured housing for decades: the structural and transportation systems of a factory-built home have always been the same thing, whether that made sense or not.

The chassis was the floor system. The chassis was the transportation system. Manufacturers designed around it, transporters drove it, and set crews installed it — all using a system that was never purpose-built for the homes being made, just inherited from the industry's trailer-hauling origins.

That's produced some real-world limitations that every manufacturer in this space knows well:

Transport height has always been a ceiling on design. Because modules ride high on a conventional chassis, DOT clearance restrictions have constrained how much vertical space a module can use. That limitation flows directly into ceiling heights, design flexibility, and the ability to build homes that look and feel like their site-built counterparts.

Staging and installation have always carried hidden costs. Crane requirements, cribbing setup, and complex offloading sequences add labor, time, and risk to every set — costs that don't show up in the factory budget but absolutely show up in the project budget.

Foundation systems have always been designed around the chassis, not the site. Because the structural demands of the chassis drive foundation engineering, project teams end up over-engineering concrete and pier systems to handle dead loads that are an artifact of transportation, not of the home itself.

The proposed HUD rule chips away at one piece of this. But the structural conversation the industry really needs is broader.

This Is Why the Uni-Frame® Was Built

The Uni-Frame® is a patented structural system developed by Uni-Frame, LLC — founded by Daryl Snader and Heath Sartini — in partnership with TinyMod®. Backed by 40+ years of industry experience, it was designed from the ground up for factory-built housing — not adapted from a legacy transportation model.

Instead of carrying a heavy, purpose-limited steel undercarriage that gets bolted to a foundation and forgotten, the Uni-Frame® functions as both chassis and floor system in a single, unified solution. It's the structural rethink the industry has needed for a long time.

Here's what that means in practice for manufacturers:

Lower transport profile. The Uni-Frame® Transportation System lowers modules to 5–10 inches off the ground during transport — compared to the industry standard of 32 inches. That's not a marginal improvement; it fundamentally changes what DOT clearance restrictions mean for design. Bridges and overhead restrictions haven't changed. The system just works around them instead of fighting them.

Up to 2 feet of additional design height. Because the module rides so low in transport, architects and designers gain usable vertical space that was previously impossible to deliver within DOT regulations. That's ceiling height. That's loft space. That's the difference between a home that looks factory-built and one that looks like the home next door.

No crane. No cribbing. The Uni-Frame® Transportation System handles staging as part of the transport process itself. What used to require dedicated crane equipment and ground crew setup is eliminated entirely — making every delivery faster, safer, and significantly cheaper on the labor side.

Clear-span structural design. The Uni-Frame® Floor System uses a clear-span approach that reduces dependency on complex foundation systems and minimizes the material costs that traditional transport constraints impose on every project. It works across foundation types — crawlspace, slab, pier — without requiring the site to conform to transport limitations.

Built for high-risk regions. The system is engineered to meet structural demands in areas with elevated wind, seismic, or weather risk — the kinds of sites where standard approaches fall short and where factory-built housing has historically struggled to compete.

One unified system, from factory floor to foundation. Attach the hitch at the factory. Connect the dolly at the rear. Transport at low profile. Set, stitch, and done — without the equipment dependencies and setup steps that have always added friction and cost to the last mile of factory-built housing delivery.

The Uni-Frame® is in the prototype and launch phase now, with full production availability expected within 4–6 months. Manufacturer spots in the first production run are limited.

What This Moment Means for the Industry

The HUD proposed rule and the Uni-Frame® are both pointing at the same thing: the structural and transportation systems that factory-built housing inherited from its past are no longer the best available answer.

The manufactured housing industry has an opportunity right now — not just to comply with a regulatory update, but to rethink the foundational assumptions that have constrained design, cost, and market perception for half a century. More affordable homes. More design flexibility. More competitive positioning against site-built construction in markets where manufactured housing has historically struggled to gain acceptance.

The regulatory environment is moving. The technology is ready. The question is which manufacturers move with it.

If you're a HUD Code manufacturer, a modular builder, or a developer working in the factory-built space and you want to understand what the Uni-Frame® could mean for your production line — we want that conversation.

And if you have a stake in the HUD proposed rule, the public comment period is open through August 11, 2026.

👉 Submit your public comment via the Federal Register

👉 Learn More About the Uni-Frame®

👉 Contact TinyMod®

TinyMod® Living is a Colorado-based IRC-code modular home company and proud partner of Uni-Frame, LLC — a patented structural system redefining transport, installation, and design flexibility in factory-built housing.