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Add living space, rental income, or a home for family — right on your Bonney Lake property. Cascade Pro, Inc designs and builds accessory dwelling units throughout Bonney Lake and Pierce County, handling everything from initial design and city permits to final inspection.
Whether you’re planning a detached backyard cottage, converting an existing garage, or adding a basement apartment, our team manages the full process so you don’t have to.
Bonney Lake allows several types of accessory dwelling units depending on your property and zoning. Cascade Pro builds all of them:
A standalone structure built on your property, separate from the main house. Detached ADUs are the most popular option, offering maximum privacy for both the homeowner and the occupant. They work best on lots with adequate backyard space and proper setbacks.
An addition built onto your existing home with its own separate entrance. This is a strong option when backyard space is limited or when you want the unit connected to the main house for accessibility or family use.
Convert your existing detached or attached garage into a fully permitted living space. Garage conversions are often the most cost-effective ADU option because the structure is already in place. We handle structural upgrades, insulation, plumbing, electrical, and finishes to bring it up to residential code.
If your home has an unfinished or partially finished basement, converting it into a legal ADU can add significant value with a lower construction footprint. We ensure proper egress windows, ceiling height compliance, moisture control, and separate entry as required by building code.
Every accessory dwelling unit project follows a structured process to keep timelines tight and surprises to a minimum:
Building an ADU in Bonney Lake is one of the smartest investments a homeowner can make — but only when it’s done right. Bonney Lake has the highest median household income ($131K) of any city in our service area, and it’s one of the fastest-growing communities in Pierce County. Homeowners here are investing in their properties for the long term.
ADU costs in Bonney Lake vary based on the type of unit, size, site conditions, finishes, and whether you’re building new construction or converting existing space. Garage and basement conversions typically come in at a lower price point than ground-up detached units because they leverage an existing structure.
Key factors that influence your project budget:
We provide detailed, transparent estimates after our initial site assessment so you know what to expect before any work begins. Every project is different — we’ll walk you through the numbers and help you make informed decisions that fit your budget.
Most residential lots in Bonney Lake are eligible for at least one ADU, though requirements vary by zoning, lot size, and access. During our consultation, we’ll verify your lot’s eligibility and walk you through what’s possible on your specific property.
Timelines vary by project type. A typical detached ADU takes roughly 6 to 10 months from design through completion, including the permitting phase. Garage and basement conversions can often be completed faster since the existing structure reduces construction time. We’ll give you a realistic timeline during our initial assessment.
Owner-occupancy requirements vary by jurisdiction. Many areas have relaxed or removed this requirement in recent years. We’ll clarify the current rules for your specific property during our consultation.
In most cases, yes. A well-built, permitted ADU adds usable square footage and income potential to your property. The actual value increase depends on the unit type, size, finishes, and location within Bonney Lake.
Yes. We manage the entire permitting process, including plan submission, revisions, and coordination with inspectors. You don’t have to navigate the building department on your own.
Short-term rental regulations vary by city and are subject to change. We build every ADU to full residential code, which keeps your options open regardless of how you choose to use the space. We recommend checking current local regulations before planning a short-term rental use.
Whether you’re planning a backyard cottage, converting a garage, finishing a basement, or adding on to your home — Cascade Pro, Inc is ready to make it happen. We’ve helped homeowners throughout Bonney Lake navigate the ADU process from first sketch to final walkthrough, and we’d love to do the same for you.
Call us today: (253) 338-1693 or fill out the form to schedule your free consultation.
Tell us about your accessory dwelling unit project. We offer free consultations for Bonney Lake homeowners.
Bonney Lake has been one of Pierce County's fastest-growing cities over the past two decades, with its population nearly doubling as families are drawn to the area's scenic setting between Mount Rainier and the Puget Sound lowlands. This growth has driven strong home values and made property improvements here a particularly smart investment.
Much of Bonney Lake's housing was built from the 1990s onward, giving the city a relatively newer housing stock compared to Tacoma or Puyallup. However, many of these homes were built with unfinished basements, oversized garages, or large lots that are now perfect for conversions, additions, and ADU construction as homeowner needs evolve.
We understand Bonney Lake's specific building codes and work with the city's Community Development Department on permits and inspections. The terrain here — with its rolling hills, established tree cover, and varied soil conditions near Lake Tapps and the plateau areas — requires contractors with local grading and drainage expertise. Our team has completed projects across Bonney Lake neighborhoods including Emerald Hills, Lake Tapps, Sky Island, and the Fennel Creek corridor, and we bring that ground-level familiarity to every build.
