ADU Construction in Kelso
Professional adu construction services in Kelso and surrounding areas • Licensed & Insured • Free estimates
ADU Construction Services in Kelso
ADU design
Permit processing
Foundation work
Complete construction
Why Choose TopVolk Construction LLC in Kelso?
Licensed & Insured
Fully licensed contractor with comprehensive insurance coverage for your peace of mind.
Local Service
Serving Kelso and surrounding areas with fast response times and local expertise.
Direct Communication
Work directly with Vladislav - no middlemen, clear expectations, honest recommendations.
Quality Guaranteed
100+ projects completed since 2023. We pay $100 for every day past the agreed deadline.
15% OFF All Labor
Book your renovation this week and save on labor costs.
Materials are billed separately and are not included in the discount.
TopVolk Construction designs and builds DADUs, attached ADUs, and basement conversions in Kelso, Washington — WA Licensed Contractor, 100+ projects since 2023.
Last updated August 2026
Kelso ADU Construction — DADUs, Basements, Rental Income
A detached garage off Rose Valley Road with a leaky roof and no plumbing isn't worth much — until WA HB 1337 turns it into a legal rental unit. TopVolk Construction builds DADUs, AADUs (attached ADUs), and basement conversions across Kelso, Washington, working within the City of Kelso's permit process and the Cowlitz County Building Department where lots sit outside city limits. Vladislav Volkov has run 100+ projects since 2023 across Seattle Metro and takes on select builds down the I-5 corridor into Cowlitz County. A lot near West Kelso with a detached shop already has power run to it; a bungalow near Tam O'Shanter Park has a full unfinished basement with 8-foot ceilings, ready for a conversion instead of new construction. Either way, the math is similar: a legal second unit with its own kitchen — GE range, stacked Whirlpool laundry, a Mitsubishi mini-split for heat — rents for real money in a county where median household income sits under $50,000. Call (206) 591-1096 for a free on-site consultation.
Kelso's housing stock skews older and modest — post-war mill-worker bungalows in the 98626 core, 1960s and '70s ranch homes spread through Rose Valley and North Kelso, plus a fair number of single-wide and double-wide manufactured homes on larger county lots out past the 98625 rural routes. That mix matters for ADU work: a 1962 rancher on a slab means a backyard DADU, not a basement conversion, since there's no basement to convert. A pier-and-beam bungalow near downtown might already have crawlspace access for a new sewer lateral, which cuts excavation cost. Cowlitz County sees real freeze-thaw cycles in winter and close to 45 inches of rain a year, so any DADU foundation here needs frost-depth footings and a vapor barrier under the slab, not a slab poured straight on grade. Inside city limits, the City of Kelso Community Development Department handles plan review; outside the limits, it's the Cowlitz County Building Department. Both check against the IRC and the statewide ADU allowances under HB 1337, but lot coverage and setback numbers shift block to block.
Common ADU Construction Concerns in Kelso
Which ADU type actually pencils out on a Kelso lot
HB 1337 lets most Kelso lots carry two ADUs, but not every lot pencils out the same way. A basement conversion under a 1968 rancher near Rose Valley might need an egress window well cut into the foundation, an LVL beam to open a wall for a legal bedroom, and a new heat source — usually a Mitsubishi mini-split — since the existing furnace duct won't cover a second dwelling unit. A backyard DADU skips the foundation-cutting problem but adds a new footing, a PSL post at the porch corner, and a separate utility trench. Basement conversions typically run $55K-$90K; a detached unit with its own kitchen and bath runs $140K-$200K+. We walk the lot and hand you both numbers before you pick one.
Separate water and sewer, or share the existing line
Cowlitz County and the City of Kelso both let a DADU tie into the existing water and sewer lateral instead of paying for a brand-new utility connection — but only if that line has capacity for two units. A lot on Allen Street with 1950s galvanized supply pipe usually needs a full re-pipe before a second unit can share it; we run new PEX and a dedicated shutoff instead of betting on 70-year-old galvanized holding up. Sewer's the same story — a 4-inch cast iron lateral sized for one household often needs a capacity check, sometimes a sister line, before the county signs off. Budget $8K-$15K for utility separation on an older Kelso lot, less if the home already has copper and PVC.
Getting the City of Kelso or Cowlitz County to sign off
A DADU in Kelso tops out at a 24-foot height limit in most zones, with rear and side setbacks usually running 5 feet — but corner lots and parcels backing the Cowlitz River floodplain near West Kelso can carry extra restrictions the standard zoning map won't show. Plan review through the City of Kelso Community Development Department typically runs 4-8 weeks for a straightforward DADU on a pre-approved plan set; a custom design or a lot needing a variance can push past 12 weeks. County parcels outside city limits go through the Cowlitz County Building Department instead, on a similar timeline. TopVolk handles the permit application, the plan set, and rough-in and final inspection scheduling — WA Licensed Contractor, direct communication with Vladislav the whole way, no permit runner passing your file around.
What a Kelso ADU actually costs, and why estimates vary
A basement conversion with an existing envelope and no new foundation starts around $55K-$85K for a studio or one-bedroom layout with a 3-piece bath. A ground-up DADU with its own kitchen, laundry, and full bath runs $140K-$200K+, depending on finish level — semi-custom cabinets versus IKEA, quartz versus laminate, a Kenmore or Frigidaire appliance package versus a Sub-Zero upgrade. Since Kelso's median household income sits under $50,000, most owners size the unit to cover its own mortgage payment through rent rather than maxing out square footage. Every quote from TopVolk is line-item — framing, MEP, insulation, finish — not a vague lump number, and missed deadlines carry a penalty written into the contract.
Building for Cowlitz County rain, not just Cowlitz County code
Kelso sits where the Cowlitz River meets the Coweeman River, which means close to 45 inches of rain most years and real humidity in the shoulder seasons. A DADU exterior holds up longer with Hardie cement-board siding than plain cedar lap, which needs re-staining every 3-4 years to fight moss and mildew on north-facing walls. Decking on a DADU porch or stair landing lasts longer in Trex or TimberTech composite than pressure-treated lumber, which checks and grays within a few seasons here. Inside, a bathroom needs a Schluter Kerdi waterproofing system under the tile, not just a vapor-permeable membrane, given how much humidity a small unit traps. Budget a re-caulk and gutter check every year; the structure, framed in Douglas-fir with R-49 attic insulation, is built for 40+ years.
Frequently Asked Questions
How fast can you get to Kelso for Adu Construction?▼
Kelso sits about 2.5 hours south of Seattle down I-5, so on-site consultations for Cowlitz County projects get scheduled in blocks rather than same-day drop-ins — usually within a week of your call. Once a project starts, Vladislav is on-site for framing, rough-in, and final walkthrough milestones, with trade coordination running through subs used on other Cowlitz County jobs. A basement conversion typically runs 6-10 weeks once permits clear; a ground-up DADU runs 4-7 months including plan review. Call (206) 591-1096 to get on the schedule.
What does an ADU cost in Kelso?▼
A basement conversion ADU in Kelso typically runs $55K-$90K, depending on egress window work and whether the plumbing rough-in already exists. A detached ADU (DADU) with a full kitchen and bath runs $140K-$200K+, driven mostly by foundation type, utility separation, and finish level — a GE or Kenmore appliance package versus a higher-end upgrade. Every project gets a line-item quote after a free on-site walkthrough, not a range pulled from a rule of thumb. Call (206) 591-1096 and Vladislav will walk the lot with you directly.
Which permit office handles ADU approval in Kelso — city or county?▼
Inside Kelso city limits, ADU permits run through the City of Kelso Community Development Department; parcels outside the city line go through the Cowlitz County Building Department instead. Both offices review against the IRC and the statewide ADU allowances under WA HB 1337, checking lot coverage, setbacks, and the 24-foot DADU height limit before approving the plan set. Straightforward projects using a pre-approved plan set often clear plan review in 4-8 weeks; custom designs or lots needing a setback variance take longer. TopVolk prepares the full plan set and permit application as WA Licensed Contractor and tracks the file start to finish.
Can a Kelso ADU share the water and sewer line with the main house?▼
Washington allows a DADU to share the primary home's water and sewer connection if the existing line has enough capacity, which saves a new tap fee. Older Kelso lots with 1950s-60s galvanized supply or a narrow sewer lateral usually need a capacity check first — sometimes a full re-pipe with PEX, sometimes just a new branch line with its own shutoff. Attached ADUs almost always share utilities with the main house through interior MEP coordination instead of a separate trench. We check pipe material and capacity during the free consultation, before it turns into a surprise change order.
What warranty comes with a Kelso ADU build, and how long should it last?▼
Framing and structural work carries a one-year workmanship warranty, with manufacturer warranties passed through on top — typically 10-15 years on Hardie siding, 25 years on CertainTeed roofing, and standard terms on a Rinnai tankless or Mitsubishi mini-split. Given Kelso's wet winters, the parts that fail first on a poorly built unit are usually flashing details and deck fasteners, not the framing itself, so we detail those connections carefully at rough-in. A well-built DADU here should run 40+ years before major systems need replacement. Missed deadlines carry a financial penalty written into the contract, not just an apology.
Does TopVolk cover other Cowlitz County cities besides Kelso?▼
TopVolk covers Kelso alongside Longview, Castle Rock, and other Cowlitz County communities along the I-5 corridor, scheduled around the primary Seattle Metro service area. Free consultations for Cowlitz County lots typically get booked within a week, with site visits grouped to keep travel efficient. Once a contract's signed, expect a permit-ready plan set within 3-4 weeks and construction start shortly after city or county sign-off. Call (206) 591-1096 to check the current schedule and get a free on-site estimate.
Ready to start your ADU Construction in Kelso?
Free on-site consultation with Vladislav. Line-item pricing — no vague ranges.
What Our Kelso Customers Say
Vlad and his team did an amazing job! They built our deck in just 3 days—no issues at all. Communication was easy, and Vlad helped us choose right deck planks. Installation was quick and flawless. Highly recommend!
Really happy with the service! Vlad was easy to communicate with and helped us to find the best garage door opener. The installation was quick and he did a perfect job. A few months later, I had a question and he came by the same day - even on a weekend. That kind of follow-up is rare these days!
Vlad replaced a bathroom exhaust fan and gave me a reasonable quote up front with no hidden fees. While replacing the fan, he discovered a plumbing vent issue causing mold. He fixed the pipe and treated the mold at a reasonable cost. I really appreciate his honesty!
Outstanding work done by Vlad and team for our home cabinet/living room interior work. Very professional and reasonable charges. Love the service.
We hired TopVolk for a full kitchen remodel and couldn't be happier. From the initial consultation to final walkthrough, Vlad was professional and attentive to every detail. The result exceeded our expectations!
Excellent bathroom renovation! Vlad completed the project on time and on budget. His attention to detail and craftsmanship is outstanding. We'll definitely hire him again for future projects.