Tualatin ADU Builder

Every Tualatin ADU begins with what the lot and the rules permit

An accessory dwelling unit can be a rental, a place for family, or a home office, but the first question is always what the site and the rules permit. JDI Construction is a family-owned design-build remodeler, and we anchor every ADU to that question: it's a second, independent home on your lot, and the zoning and utilities decide what's possible before any design does. The Portland metro is generally very ADU-friendly, which usually helps Tualatin homeowners — but rules still vary by city and jurisdiction, and every lot is different, so we confirm what your specific property allows before drawing anything. Tualatin is newer Southwest suburban, close to the Tualatin River, and the particulars of a given lot — how it drains, where the utilities run, how much room the setbacks leave — shape what a second unit can be.

Our designers and trades work as one team, so the unit you approve is grounded in what the site and the code actually permit — we don't hand a hopeful floor plan to a separate crew and find out later it won't pass. Here's the range of ADUs we build, what decides what's possible, and what to expect on cost and timeline.

The parts that matter most

A good ADU comes down to a handful of things handled in the right sequence. These are the parts we lead with:

1. 1
   

   Feasibility firstConfirming what your specific lot allows before any design begins.
2. 2
   

   Site & utilitiesGrading, access, and connecting sewer, water, and power to a new dwelling.
3. 3
   

   Designing for smallMaking a compact footprint live large with light, storage, and ceiling height.
4. 4
   

   PermittingNavigating the local ADU rules and inspections, handled for you.

A few decisions worth making early

The choices that shape an ADU land well before design. First is feasibility. The metro's ADU-friendly climate generally helps, but Tualatin's rules are the city's and the county's, not automatically Portland's, and no two lots are alike once drainage, access, and utility locations come into play — so we confirm what your parcel permits before drawing. Second is type and use: a garage conversion, a basement unit, an attached addition, and a detached cottage differ sharply in cost and in what the site has to support, and building for rental income, family, or a home office steers the layout. Third is budgeting for what's out of sight — the sewer, water, and power connections and the system development charges that a new dwelling brings. Given how much newer Tualatin lots can vary in grade and drainage near the river, we scope that site and utility work early so nothing surprises you after design.

What Tualatin homeowners build ADUs for

The ADUs we're asked about in Tualatin generally serve one of a few needs: a rental unit that draws on the region's steady demand for housing, a private space for aging parents or adult children who want to stay close without sharing a roof, or a home office or studio kept separate from the main house. Each moves the design a different direction — a rental favors durability and a separate entrance, a multigenerational unit favors single-level, step-free living.

Tualatin's newer suburban lots tend to lend themselves to a detached cottage or an attached unit, though an existing garage can open up a conversion route as well. Whatever the use, we design a compact footprint to live larger than its square footage, using light, storage, and ceiling height to keep a small home from feeling small.

What does an ADU cost in Tualatin?

ADU cost is driven first by type: a garage or basement conversion that reuses an existing structure generally costs less than a detached cottage built from the ground up. After that come size, finish level, and — the part homeowners most often underestimate — the site and utility work. Extending sewer, water, and power to a new dwelling, managing grading and access, and covering connection fees can take a meaningful share of the budget, which is why we scope it early. With design and trades both in-house, we give you an itemized estimate once we know what your lot allows and which type fits, so the number reflects your project rather than a generic per-square-foot figure.

How long does an ADU take to build?

An ADU runs on three clocks: feasibility and design, permitting, and construction. Permitting for a second dwelling generally takes longer than a remodel because it involves zoning and utility review, so we build that time into the plan rather than promising a quick turnaround. Once permits are issued, construction depends on the type — a conversion is faster than a ground-up cottage. We give you a realistic schedule after the feasibility check, handle the permitting, and keep you updated through our client portal as the unit takes shape.

Why homeowners in Tualatin choose JDI

An ADU rewards a builder who understands the rules as well as the construction, because the project can stall at the permit counter long before the first wall goes up. As a single accountable design-build team, we handle the feasibility, the design, the utility connections, and the build under one roof, so nothing slips between a zoning question and the crew on site. We manage the permitting, keep you informed through our client portal, and stand behind the work with a five-year workmanship warranty. We're based across the river in Vancouver, a short drive away, close enough to stay responsive through a project this involved.

JDI Construction — "Built by family. Trusted by neighbors." Design-build remodeling and ADU construction based in downtown Vancouver, WA, serving Tualatin and the greater Portland–Vancouver metro since 2007.