Buyer Guide/
State Modular (Factory-Built) Building Programs

Standard

State Modular (Factory-Built) Building Programs

State-adopted building codes; program rules vary by state
US
State-provincial
State housing or building agencies (varies by state), e.g. Colorado Division of Housing, Arizona Department of Housing, California HCD

Many states run programs for modular (factory-built) homes built to the state's adopted building code, not the federal HUD Code. The state, or an agency it approves, reviews plans and inspects in the factory, and each unit gets a state insignia or label.

Covers state plan approval, factory inspection and insignia for modular homes built to state-adopted codes; does not cover zoning, foundations, site and utility work, other states' approval, financing, insurance or transport damage.

Applies to

Modular Homes
ADU & Backyard Homes

Who checks it

The state agency, or third-party agencies it approves, reviews plans and inspects at the factory. Local building departments usually permit and inspect the foundation and installation on site. Roles vary by state.

When it matters

When you buy a modular home or backyard unit for a specific state. The state insignia tells local officials the factory-built work was inspected. Without it, a local office may not allow the unit to be installed.

What this establishes

  • The home's design and plans were approved before building, under the state's adopted codes.
  • Work done in the factory, including parts hidden inside walls, was inspected by the state or an approved agency.
  • A state insignia, label or certificate on each unit or module showing it passed.

What it does not establish

  • Whether the home may be placed on a lot. Local zoning and permits decide placement.
  • Foundation, installation, site work and utility hookups. These are often permitted and inspected locally.
  • Approval in another state. A unit built for one state's program may need extra steps elsewhere.
  • Financing, insurance, warranty, or damage during transport.

How to verify it yourself

  1. Look for the state insignia or label on each unit or module. Location varies by state; in California it may be removed after installation.
  2. Ask the manufacturer which state program approved the plans. Check its license with that state agency.
  3. Ask your local building department for the installation permit and final inspection or certificate of occupancy.

Your next step

Call your local building department before you buy. Ask what state insignia it accepts for modular homes and what permits the foundation and hookups need.

Take the next step

United States

Rules vary by state. Three examples from state agency pages:

  • Colorado (Division of Housing): the state must approve modular plans before construction and certifies structures after inspection. Over 300 local jurisdictions with building departments review and inspect foundations. Where there is no building department, the state reviews the foundation.
  • Arizona (Department of Housing): modules must be built in a state-certified plant with continuing in-plant inspections. No module may be shipped to or within Arizona without an Arizona insignia. Each installed module must display an Arizona Modular Certificate. Buildings not first built to Arizona rules may need a reconstruction certificate.
  • California (Department of Housing and Community Development, HCD): factory-built housing sold to first users must carry an HCD Insignia of Approval, issued through an HCD-approved quality assurance agency for units with prior plan approval. Local agencies permit and inspect installation. Zoning, snow load and wind pressure rules are left to local jurisdictions.

A modular home built to a state code is different from a manufactured home built to the federal HUD Code. Check which label a home carries.

Canada

Questions to ask

No items found.

Confirm requirements for your property

Confirm with your local building and planning department.

Explore property questions

Sources

Edition:

Each state adopts its own code editions and updates its rules on its own schedule. Colorado's new factory-built rules took effect July 1, 2026. Check the state agency's page for current rules.

Last reviewed

October 26, 2026