You want an ADU in Longview. A real second home on your property. Not a shed with plumbing. Not a half-finished “someday” project that drags on for a year.
Here’s the part most people learn the hard way: The build is not the hard part. The hard part is everything that happens before the build. The approvals. The setbacks. The utility plan. The foundation and access. The jurisdiction questions that sound small until they become expensive.
If you are searching for a Longview WA ADU builder, you are probably trying to avoid two outcomes:
You spend money on plans before you know what your lot can legally support.
You pick a builder who is great at construction, but not great at navigating the process in Longview and Cowlitz County.
Wolf Industries has built many ADUs in the Longview area, and we start the same way every time because it prevents the biggest mistakes.
Start with our free property evaluation form. It is the fastest way to find out what your site can support, what your realistic next steps are, and what risks you should address before you commit.
Why Longview homeowners are building ADUs right now
People do not wake up one morning and think, “I would love to spend my weekends meeting inspectors and comparing setback rules.” There are various reasons that homeowners are building more and more ADUs.
- They want a better life on the same property.
- Rental income helps the mortgage feel lighter.
- A place for parents who want independence without being far away.
- A space for adult kids who need a landing pad that is not your living room.
- A private office or studio that can later become a rental.
In the Longview area, it often comes down to one simple question:
What do I need to do to build an ADU on my property?
If you want clarity fast, fill out Wolf’s free property evaluation form and let’s confirm what is possible on your lot.
Longview city limits vs Cowlitz County rules: the detail that changes everything
In the Longview area, the rules can change depending on whether your property is inside City of Longview limits or in unincorporated Cowlitz County.
The City of Longview’s Planning FAQ notes that building a detached apartment behind an existing house may be possible as an accessory dwelling unit, and it also mentions an owner-residency requirement for that scenario.
Cowlitz County’s FAQ takes a different approach. The County says ADUs require planning approval and a residential building permit, can be manufactured or modular, and lists a maximum size of 1,200 square feet. The County also notes that in areas classified as Urban and Suburban in its Comprehensive Plan you may be able to build up to two ADUs (one attached and one detached), and that there is no owner-occupancy restriction for the primary home or ADU.
One more important layer: Washington State has updated ADU requirements through House Bill 1337, with state-level standards around things like allowing two ADUs in certain areas and limiting owner-occupancy requirements in jurisdictions that fully plan under the Growth Management Act.
Rules evolve, and local requirements can change as cities and counties update their codes.
That is why a serious Longview WA ADU builder does not guess.
We verify your jurisdiction and constraints first.
If you want that verification done quickly, start with Wolf’s free property evaluation form.
What makes a “real” Longview WA ADU builder different
Plenty of people can build a structure.
An experienced ADU builder in Longview knows how to deliver a finished, permitted, code-compliant home that makes sense financially and actually gets approved.
Here are the common failure points we see when homeowners try to piece it together:
Plans before feasibility
A homeowner pays for drawings, then learns the ADU footprint cannot meet setbacks or utility requirements. The project restarts, and the budget inflates.
Underestimating sitework
ADU budgets are often blown by access, excavation, trenching, drainage, and utility connections. These are not “extras.” They are the job.
Jurisdiction surprises
City vs county rules, zoning details, and environmental constraints can change the path of the entire project.
Wolf has built many ADUs in the Longview area, and our process is designed to prevent these problems before they start.
The Wolf way: how Longview ADU projects should start
This is the part most builders do not emphasize because it is not glamorous.
It is also the part that makes the rest of the project smoother.
Before you get emotionally attached to a layout, we want answers to the questions that actually control your project:
- Where is your property located, city or county?
- What is your zoning and what does it allow?
- What are the physical constraints: slope, access, utilities, critical areas?
- What is the best placement concept for privacy, function, and cost control?
When you complete Wolf’s free property evaluation form, our team can begin narrowing this down so you can make decisions with real information instead of assumptions.
Build and deliver with a predictable process
Once feasibility and permitting are aligned, the build phase becomes far more straightforward.
That is where Wolf’s factory-built systems and proven delivery approach shine, especially for homeowners who want a cleaner timeline and fewer weather-related delays.
If you want to see what that process looks like end-to-end, start with the free property evaluation and we will map the best path for your site.
Costs in Longview: what actually drives your ADU budget
If you have asked, “What does an ADU cost in Longview?” you are not really asking for a number.
You are asking what makes the number go up or down.
Here are the drivers that matter most:
Sitework and access
Tight access, steep slopes, unusual excavation requirements, retaining, drainage, and soil conditions can move costs quickly.
Utilities
Water, sewer, power, stormwater, and trenching are major cost categories.
If you are on a domestic well or onsite septic in parts of the county, Cowlitz County notes you may need to coordinate with their Environmental Health Unit for requirements, and they provide contact details for that department.
Foundation type
Stem wall, slab, crawl space, site conditions, and frost considerations can change scope.
Permitting review time and completeness of submittals
The City of Longview’s Building Division notes residential plan review time expectations and outlines how inspections are scheduled and performed.
The more complete and accurate your submittal package is, the less friction you face.
This is one of the biggest reasons to choose a builder who has already done many ADUs in the Longview area.
If you want a realistic budget range based on your actual property, the fastest next step is Wolf’s free property evaluation form.
“Do I even qualify?” The most common Longview ADU questions
Can I build an ADU behind my house in Longview WA?
The City of Longview’s Planning FAQ indicates that building a detached apartment on the same lot as an existing residence may be possible as an accessory dwelling unit.
The right answer depends on your zoning, setbacks, and current requirements at the time you apply.
Do I need permits?
Cowlitz County states ADUs require planning approval and a residential building permit.
The City of Longview’s Building Division describes their permitting and inspection services and how to apply for permits.
Can an ADU be modular?
Yes. Cowlitz County explicitly notes ADUs can be manufactured or modular homes.
How big can my ADU be in Cowlitz County?
Cowlitz County lists a maximum ADU size of 1,200 square feet.
Can I build two ADUs?
Cowlitz County notes that in areas classified as Urban and Suburban in the Comprehensive Plan, you may be able to build up to two ADUs (one attached and one detached).
Washington State has also adopted ADU requirements that, in certain jurisdictions and contexts, require allowing two ADUs with specific standards.
The correct answer for your property depends on your jurisdiction, location relative to urban growth areas, and how local code aligns with state law.
That is exactly what the property evaluation helps confirm.
References (official resources)
City of Longview, WA: Planning Division FAQ page
City of Longview, WA: Building Division (permits, inspections, hours, contact details)
Cowlitz County, WA: “Can I build an Accessory Dwelling Unit (ADU) on my property?” FAQ
Cowlitz County, WA: Building & Planning department page (contact and hours)
Washington State Department of Commerce: Accessory Dwelling Units (HB 1337 overview and requirements)