ADU guest house construction by MIRAI Constructions
ADU Construction

Accessory Dwelling Units That Add Value & Versatility

Guest houses, garage conversions, in-law suites, and rental units. MIRAI handles every step from design and permits to construction and finishing.

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Why Build an ADU?

Accessory dwelling units are one of the smartest investments a homeowner can make. Whether you need a guest house for visiting family, a private home office, a rental income property, or an in-law suite for aging parents, an ADU adds both functionality and significant value to your property.

Arizona's evolving zoning regulations have made ADU construction more accessible than ever, and MIRAI Constructions is at the forefront of this growing market. We handle everything, from navigating local ordinances and securing permits to designing and building a space that matches the house already on the lot.

ADU Types We Build

  • Detached Guest Houses: Standalone structures with full kitchens, bathrooms, and living areas that provide complete privacy and independence.
  • Garage Conversions: Transform your underutilized garage into a fully functional living space with proper insulation, HVAC, plumbing, and finishes.
  • In-Law Suites: Attached additions designed for multigenerational living with separate entrances and self-contained amenities.
  • Rental Income Units: Purpose-built units designed to maximize rental income with durable materials and tenant-friendly layouts.
  • Home Office Studios: Dedicated detached workspaces for remote professionals, artists, or entrepreneurs.
  • Pool Houses & Casitas: Arizona-style outdoor living spaces with kitchenettes, bathrooms, and covered patios.

Full-Service ADU Construction

Unlike many contractors who only handle the build, MIRAI provides a complete ADU solution. We research zoning requirements for your specific lot, create or coordinate architectural plans, manage all permits and inspections, and deliver a finished space that meets all building codes and your personal vision.

How It Works

Our ADU Process

From zoning research to move-in ready, we handle every detail.

1

Zoning & Feasibility

We research your lot's zoning, setbacks, and ADU regulations to confirm what is possible.

2

Design & Permits

Architectural plans, engineering, and full permit management with the local municipality.

3

Construction

Foundation, framing, MEP, finishes, built to code with regular progress updates.

4

Final Inspection

Certificate of occupancy, walkthrough, and keys to your new ADU.

Why It Matters

The crews on your job work for us

Most general contractors manage subcontractors. We self-perform the trades that decide cost and schedule, which means the people on your site answer to us directly.

  • Framing
  • Drywall
  • Insulation
  • Painting
  • Flooring
  • Roofing
  • Finish carpentry

That is what makes a five in the morning concrete pour something we can commit to rather than request. It is also why our estimates come back in CSI division format instead of a lump sum, and why most bids go out within 72 hours.

Building in Arizona

Timing an ADU build around the heat

An ADU is a small building that still needs a slab, an envelope and an exterior finish, so it runs into every one of Arizona’s temperature constraints in a compressed timeline.

The slab is the one to get right. Concrete placed above 90°F sets too fast, and most specifications cap placement temperature at 90 to 95°F. Summer pours go before six in the morning, with chilled mix water and continuous misting during cure. Stucco and exterior paint then want the October to April window, which is worth knowing before you set a move-in date.

Read how we build around the heat, including the material limits, the seasonal work window, and real Gilbert permit timelines.

FAQ

ADU Construction Questions

Yes. As of 2026 Gilbert allows one attached and one detached ADU by right in every single-family zoning district, with a third detached affordable unit permitted on lots over one acre. These are reviewed administratively, with no public hearing. We confirm the zoning and setbacks for your specific lot before you spend anything on design.
ADU costs vary based on size, type (detached vs. conversion), finishes, and site conditions. Garage conversions typically start lower than ground-up detached units. We provide a detailed, transparent estimate during the consultation phase so there are no surprises.
Garage conversions can be completed in 6 to 10 weeks. Detached ADUs typically take 3 to 5 months from permit issuance, depending on complexity. The permit review in Gilbert typically runs three to six weeks for an ADU, assuming a complete submittal.
In most cases, yes. A well-built ADU adds usable square footage and rental income potential, both of which increase property value. Many homeowners see a strong return on investment, especially in high-demand rental markets like the Phoenix metro area.
As of 2026 Gilbert allows one attached and one detached ADU by right in every single-family zoning district, with a third detached affordable unit permitted on lots over one acre. These are reviewed administratively, with no public hearing. We confirm the specific zoning and setbacks for your lot before you spend anything on design.
In Gilbert, ADUs and larger additions typically take three to six weeks for plan review, assuming a complete submittal. The site plan has to show the primary residence footprint, the ADU footprint, all setback dimensions, parking, and utility connection points.

Thinking About Building an ADU?

Get a free zoning check and project estimate. We will evaluate your property and walk you through the entire process.

Or call us directly: (615) 335-5587