Modular ADU Homes for Your Backyard

What Is a Modular ADU?

An accessory dwelling unit, or ADU, is a separate home on the same lot as a main house. You might use it for family, visiting guests or rental housing where local rules allow.

Irontown’s ADU plans are factory-built to the International Residential Code, the same code as a site-built house. The modules travel by truck and are set by crane on a permanent foundation. Once set, your ADU is a permanent building on the lot.

On this page, “tiny home”, “casita”, “backyard home” and “prefab ADU” are everyday names for the same thing. A tiny home on wheels or a park model RV is a different product that most ADU laws leave out.

Find the ADU Rules for Your State

ADU rules come from state and city law. Each guide covers state rules, city and county rows, sizes, occupancy, permits, fees and timelines. Irontown delivers to Utah, Arizona, California, Colorado, Idaho, Montana, Nevada, Oregon and Wyoming. You must confirm requirements with your city or county planning and building office before ordering; MCO strongly recommends contacting them.

Explore Irontown’s ADU Plans

Choose from 11 plans spanning 497 to 1,220 sq ft, with one and two story layouts and one to three bedrooms. Four finish series are available: Designer, Modern, Balance and Rustic. Starting prices include delivery and standard crane set within 250 miles of the Spanish Fork factory.

Mysa 500

497 sq ft · 1 bed, 1 bath · from $137,800

See the Mysa 500 plan

Cabana 500

497 sq ft · 1 bed, 1 bath · from $179,700

See the Cabana 500 plan

Sledhaus 500

580 sq ft · 1 bed, 1 bath · from $174,200

See the Sledhaus 500 plan

Cabana 700

718 sq ft · 2 bed, 1 to 2 bath · from $170,900

See the Cabana 700 plan

Torrey Flats

696 sq ft · 1 bed, 1 bath · from $188,200

See the Torrey Flats plan

Morada 800

793 sq ft · 1 to 2 bed, 1 to 2 bath · from $236,100

See the Morada 800 plan

Morada 1000

989 sq ft · 1 to 2 bed, 1 to 2 bath · from $240,700

See the Morada 1000 plan

Eagle Landing 1000

1,000 sq ft · 2 bed, 2 bath · from $221,100

See the Eagle Landing 1000 plan

Rabbit 1000

1,002 sq ft · 2 bed, 2 bath · from $232,300

See the Rabbit 1000 plan

Walker

1,165 sq ft · 2 bed, 2 bath · from $268,200

See the Walker plan

Eagle Landing 1220

1,220 sq ft · 3 bed, 2 bath · from $260,500

See the Eagle Landing 1220 plan

What Your ADU Price Includes and Costs on Top of the Home Price

The Utah Designer Series starting price includes modules, delivery and standard crane set on your foundation within 250 miles of the Spanish Fork factory. Beyond that, transportation is $12.75 per mile per truckload, plus a pilot car if required. Single-module plans use one load; bigger plans use two modules on two trucks, stitched together on your foundation. Your written custom quote confirms loads and final pricing, including finish series, options and transportation, before anything is built.

These are costs on top of your home price, charged by your general contractor, city and state and quoted by your contractor and city, not MCO. They include foundation, site work and grading, utility trenches and connections, the stitch that closes and finishes seams between modules, permits, plan review and impact fees, site and foundation engineering, sales tax, steps, porches, decks, landscaping and a transport touch-up allowance.

How Long Does a Modular ADU Take?

Irontown outlines three phases, from feasibility through construction and delivery. These are its target durations. Local permit review adds time beyond these phases, and the city or county sets that schedule. Permit, building or site delays can affect your timeline.

1. Feasibility Review (1 to 2 weeks). Irontown reviews the site virtually, crane placement, delivery route, budget, schedule and building requirements. This phase includes financing assistance and contractor support. The $2,000 fee is applied to your final contract price.
2. Pre-construction Agreement (2 to 3 months). Irontown visits the site, completes detailed planning and limited design customization, and addresses code requirements for the location. You make selections with its interior designer and receive engineered, stamped plan sets for the building permit.
3. Construction and Delivery (12 to 16 weeks). Irontown builds, ships and sets the modules. Its goal is to meet these timelines and communicate about any permit, building or site delay.

The Six On-Site Steps

Your general contractor handles the on-site work and coordinates with Irontown for delivery and set day. Here is how the work moves from preparing your lot to handing over your home and supporting it after move-in.

1. Plan and Prepare. Your contractor evaluates and prepares the site, handles permitting, and coordinates the work schedule and delivery logistics with Irontown.
2. Build the Foundation and Utilities. Your contractor builds the foundation to the structural engineer’s specifications and installs water, sewer, electrical and gas connections.
3. Receive and Set the Modules. Your contractor prepares access and staging areas, receives and inspects the modules for transit damage, and coordinates the crane placement on your foundation.
4. Join and Finish. Your contractor connects and weatherproofs the modules, finishes the interior and exterior seams, completes exterior work, and connects and tests plumbing, electrical, heating and cooling systems.
5. Inspect and Hand Over. Your contractor coordinates final inspections, tests building systems, completes remaining fixes, and walks through the home with you before handing over documents and keys.
6. Support After Move-In. Ongoing support includes warranty service for covered issues after occupancy and help setting up maintenance schedules if you want it.

You’ll Need a General Contractor

A licensed general contractor is required for your on-site work, including the foundation, utilities, set-day coordination, stitch and finish. Your contractor prices that work separately from the modular home. Irontown has connections to some general contractors, so contact MCO to see whether we can recommend one for your area. Irontown’s feasibility review includes contractor support.

If you’re a general contractor building ADUs for your clients, email support@mycozyoutdoors.com to join the MCO contractor network.

Visit the Factory in Spanish Fork, Utah

See where your home takes shape. Irontown has more than 40 years of experience building homes and commercial buildings. Schedule a factory visit through MCO to walk through finished modules on the line and see the finish series in person. The factory is in Spanish Fork, Utah, about 52 road miles south of Salt Lake City and about 9 miles from Provo.

Common Questions

Rules were read in September 2026. This summary is not legal advice or approval; rules change and local offices decide their application. MCO takes no responsibility for zoning, permits, impact fees, septic approval or code compliance. You are responsible for confirming these matters with city or county planning and building offices and the health department for septic, and obtaining required permits before ordering. MCO strongly recommends contacting those offices and can share code sections and suggested questions.

Get Your ADU Quote and Free Zoning Guidance

Tell us your location and preferred plan. Your quote includes free zoning guidance: MCO can share code sections it found and suggest questions. You must confirm requirements with your city or county planning and building office before ordering; MCO strongly recommends contacting them.