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ADU

Accessory Dwelling Units

We build backyard cottages, casitas, mother-in-law apartments, and more.

An Accessory Dwelling Unit (ADU) is a small structure built on the property of an existing home. Sometimes called a granny flat, secondary suite, or in-law unit, they’re commonly used to create additional space for multi-generation families, home offices, or rental properties.

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We're a licensed general contractor with local teams across the greater Seattle, Portland, San Francisco, San Jose, San Diego, Denver, and Phoenix areas.

ADU FAQ

Are there different types of ADUs? 

There are lots of different types of attached and detached ADUs; they come in all shapes and sizes. Some look like something you’d see on HGTV’s Tiny Homes, others look more like a full-fledged guest house. The design all depends on your goals, budget, and local building codes. 

For budgeting purposes, we categorize ADUs into two types: prefabricated and custom. 

  • Prefabricated: Structures are manufactured off-site and generally come as a “kit” that includes the structure all the way through to the finishes and appliances. Prefabricated can oftentimes be more cost-effective, but could also limit the owner in regards to design and material selections.
  • Custom: Similar to a custom new construction home, these can be fully customized to fit your needs, designs, and finishes.

How does the ADU process work? 

Feasibility

Every city has its own building codes that apply to ADUs. So our first step is to review the size, type, and placement of an ADU on your property according to codes and regulations required by your municipality. This can be completed by Pro.com working in conjunction with our design partners.

Design

From here, you’ll work with an architect to design a structure that best fits your needs and local codes. Pro.com has a number of architects in the area that specialize in backyard cottages for both custom designs and prefabricated design templates.

Bidding

Our in-house estimation team builds a detailed, comprehensive estimate based on the architect’s design specifications. We also account for your preferred finish selections, goals, timeline, and other project requirements.

Permitting 

We work with you and the architect to get permit-ready plans and engineering assessments required for proper permits. Permitting time varies between cities and the complexity of the project. 

Planning 

Project planning is a critical part of any construction project. We work closely with you and the architect during this phase. Planning includes developing the project schedule, material selections, material sourcing among other tasks.

Construction

We build your ADU from start to finish. This includes everything from initial site work to excavation, foundation, framing, finishing and ultimately handing you the keys!