If you own land in Kittitas County and you've thought about adding an Accessory Dwelling Unit (a small second home for rental income, aging parents, an adult child, or a future guest house) 2026 is a moment worth paying attention to. Washington State has rewritten the rules around ADUs, Kittitas County is in the middle of a Comprehensive Plan update due by the end of 2026, and the gap between what state law requires and what local code currently says has never been wider.
This guide covers what's allowed today, what's changing soon, and the practical questions you'll need to answer before you start designing. None of it is legal advice; every property is different, and the only authoritative source for your specific parcel is Kittitas County Community Development Services. But knowing the right questions to ask is half the battle.

First, the most important distinction: UGA or rural?
Kittitas County's ADU rules split into two very different worlds depending on whether your property sits inside an Urban Growth Area (UGA) or in unincorporated rural land.
Urban Growth Areas in Kittitas County include the city limits and adjacent expansion zones around Cle Elum, South Cle Elum, Roslyn, Ronald, Easton, Ellensburg, and Kittitas. If your address has city water and city sewer, you're almost certainly inside a UGA. If you're on a well and septic with several acres, you're almost certainly outside one.
This matters because Washington's House Bill 1337, the major 2023 ADU reform, only applies inside UGAs. Outside, the older county rules still govern.

What HB 1337 changed (inside UGAs)
HB 1337 took effect statewide in 2023, with cities and counties required to bring their codes into compliance through 2024 and 2025. For lots inside an Urban Growth Area, the law requires local governments to:

• Allow at least two ADUs per lot (in any combination of attached, detached, or conversions of existing structures).
• Allow ADUs of at least 1,000 square feet; local code can permit larger but cannot cap below this.
• Eliminate owner-occupancy requirements. You no longer have to live on the property to build or rent an ADU.
• Cap impact fees on ADUs at no more than 50% of what's charged for the primary unit.
• Limit off-street parking to one space per ADU, with no parking required at all within a half-mile of a major transit stop.
• Allow building heights of at least 24 feet for ADUs (or up to whatever the primary residence is allowed).

In practice, this means a UGA homeowner in Cle Elum or Ellensburg now has significantly more flexibility than they did a few years ago. The City of Cle Elum and the City of Ellensburg are working through their code updates to bring local zoning into HB 1337 compliance. If you're inside city limits, confirm the current city code, not just the county code, since the city is your permitting authority.

What the rules look like outside a UGA
Most of Kittitas County by land area sits outside any UGA, including most of Suncadia, Tumble Creek, Ronald, the Teanaway, and the rural areas surrounding Cle Elum and Ellensburg. Out here, HB 1337 does not apply (at least not yet), and Kittitas County Code Title 17 still governs.

Under the existing county code for rural and resource lands, the typical rules look like this:

• ​One ADU per lot (3 acre minimum) is generally allowed, often as a conditional use rather than an outright permitted use.
• The owner of the property must live in either the primary residence or the ADU.
• The ADU must meet all setback requirements for its zone, and in some zones (Commercial Forest, for example) those setbacks can be 200 feet from every property line.
• The ADU must meet Kittitas County Health Department standards for water and septic. This is often the controlling constraint on rural lots.
• Mobile homes and recreational vehicles are not allowed as ADUs.
• Additional off-street parking is required.
• An ADU is not allowed on a lot that already has a Special Care Dwelling or Accessory Living Quarters.

Rural ADU permits typically also require a land use permit in addition to the building permit, which adds time and cost to the front end of a project.

The Comprehensive Plan Update: What to Watch in 2026
Kittitas County is required to complete its periodic Comprehensive Plan update by December 31, 2026. As part of that update, the county must address ADU regulations alongside middle housing and design review. This is the window in which rural ADU rules could meaningfully change, though exactly how is still being worked out at the planning commission level.
If you're planning a rural ADU project for 2026 or 2027, it's worth keeping an eye on the county's draft regulations as they're released. A project designed to current rules may be designable to better rules within months.

The septic question
For most rural Kittitas County properties, the binding constraint on whether an ADU is even possible isn't zoning. It's the septic system. Adding a second dwelling unit means adding bedrooms, which means proving the existing septic system can handle the additional load, or designing a system upgrade or a separate septic system for the ADU.
Before any ADU design work begins on a rural property, the recommended first step is a conversation with the Kittitas County Environmental Health Department about your existing system's capacity and any required upgrades. A septic feasibility check costs little and can save you from designing an ADU you can't actually permit.

What a typical Kittitas County ADU project looks like
From first conversation to permit submittal, a Kittitas County ADU typically takes 6--10 weeks of design time, depending on site complexity, septic engineering, and how quickly the structural engineer can turn around calculations. Construction time depends on the builder, but a 600--900 square foot detached ADU usually frames and finishes in 4--6 months once permitted.

A complete permit submittal for an ADU in Kittitas County generally includes:

• Site plan showing setbacks, easements, septic, well, and any critical areas.
• Floor plans for both the primary residence and the proposed ADU.
• Building elevations and section drawings.
• Foundation plan and structural engineering.
• Energy code compliance worksheets per the Washington State Energy Code.
• Septic and well documentation from Environmental Health.
• Plans drawn at quarter-inch scale on minimum 11x17 paper, with two complete sets submitted.

How Henrichsen Design helps
As a Cle Elum based architectural design firm, Henrichsen Design has been producing ADU drawings for Kittitas County properties for years. That includes detached ADUs on rural acreage, garage conversions in Cle Elum and Roslyn, basement ADUs on sloped lots, and attached ADUs on smaller in-town parcels. Each project starts with a conversation about what you're trying to accomplish, what your site allows, and which of the dozens of small decisions in an ADU design will most affect cost, livability, and permittability.
If you're considering an ADU on your Kittitas County property, the best first step is a no-cost initial consultation. Call 509-260-0614 or fill out the Design Questionnaire on the Henrichsen Design website to share basic project details: lot location, what you're hoping to build, and any constraints you already know about. You'll hear back within one business day.

Today's project: Sprawling Farmhouse coming soon to the Upper Peoh Pt. area.

This cabin, nestled in the pines and built in the 1970's, was begging for an update. The interior was gutted, completely redesigned and new additions grace three sides, breathing new life into the old chalet. Gone are the too small and non-functional spaces.  
It's important to enhance the existing structure while ensuring it harmonizes with the natural surroundings and itself. Too often you see additions that are not cohesive with the base structure. The new and the old look as if they're at war with each other. Yuck...
We work closely with homeowners to understand their needs and desires, balancing design decisions with aesthetic appeal, functionality, and your budget in mind. 

A client in Idaho sent me some progress pics this morning. I love seeing these come to life. (Note: These were very low resolution, so I upscaled them. AI decided to wrinkle the house wrap.) This Mountain Modern is looking good. 

Throughout the month of May, I donated much my free time constructing a mobile registration booth for the Cle Elum Downtown Association. It was a fun little project to design and build. Look for it at upcoming events. If you're interested in volunteering you can contact them through the website listed below.
CEDA is a local non-profit that promotes economic vitality in the historic downtown core, supporting local merchants. They also put on numerous events throughout the year, relying almost entirely on volunteer labor, including Pioneer Days, Boo-Elum, Downtown Clean Up, Plaid Friday, Christmas in Cle Elum and more.
https://cleelumdowntown.com/

Most people hiring a building designer for the first time have spent months, maybe years, thinking about their future home. They know what they want. They have a Pinterest board. They've watched enough renovation shows to have opinions about open floor plans and butler's pantries. What they usually haven't thought much about is the working relationship itself: how the design process actually unfolds, what makes it go smoothly, and what causes projects to stall, cost more than expected, or produce a result the client doesn't love.

This post is about that. Not the architecture. The working relationship. And more specifically, what you can do from your side to make the whole thing go well.

Do the hard thinking before you show up
The single most useful thing you can bring to a first meeting with a building designer isn't a mood board. It's a realistic answer to three questions: How do you actually live? What does this building need to do? And what is your real budget?

"How we live" sounds obvious until you try to answer it honestly. Do you actually cook elaborate meals, or does "open kitchen" just sound appealing? Do you work from home and need quiet, or do you just like the idea of a home office? Do you have people over twice a week or twice a year? The design decisions that follow from these answers are very different from each other, and a designer can't make them for you.

The budget conversation is harder, because most people are afraid to commit to a number before they understand what things cost. That's reasonable. But going into a design process with "we don't really have a budget yet" wastes time and money, because your designer might spend weeks developing a scheme that doesn't fit your financial reality. A rough, honest number, even if it shifts later, is more useful than no number at all.

If you don't know what things cost to build in Kittitas County right now, ask. A designer who works here regularly can give you a realistic range. Current construction costs in this region are not the same as national averages, and they are not the same as they were three or four years ago.

Bring your constraints, not just your wishes
Many clients arrive at a first meeting with a wish list and not much else. That's a reasonable starting point. But the most useful first-meeting information is actually your constraints: the site-specific facts that will shape every design decision downstream.

If you already own your lot, bring what you know about it: the slope, the utility situation, whether you're on well and septic or municipal services, any CC&Rs or design review requirements. Suncadia and Tumble Creek both have design review, and those requirements can meaningfully affect what your home looks like and what it costs to build. If there are any critical area designations, wetlands, or steep-slope buffers on your parcel, those matter early.

If you don't know these things yet, that's fine. But understanding that they need to be figured out early, before the design goes very far, is important. The cost of discovering a 50-foot wetland buffer after schematic design is complete is much higher than the cost of discovering it before you start.

Constraints aren't obstacles. They're the parameters that make a design specific to your site rather than generic. The home that works on a steep north-facing lot above Cle Elum looks nothing like the home that works on a flat sunny parcel outside Ellensburg. That's not a problem. That's the whole point of custom design.

Listen when your designer pushes back
Sometimes your designer will tell you that something you want is a bad idea. Not "we can't do that," but "here's why that's going to cause you problems."

It might be a feature that looks great in photos but adds cost out of proportion to its value. It might be a layout that feels spacious in a drawing but will feel awkward to actually live in. It might be a site placement decision that seems fine until your designer explains what the drainage looks like in March. It might be a roof form that works aesthetically but will hold snow in a way you'll regret.

You're not obligated to take the advice. It's your house. But you're paying for expertise, and the most productive design relationships are the ones where both sides feel free to say what they actually think. A designer who just draws whatever you ask for without any professional input isn't giving you the full value of the engagement.

Understand what "revisions" actually means
Design is an iterative process, and revisions are a normal part of it. Most design agreements include a defined number of revision rounds in the base scope. What those mean in practice varies, but the general principle is consistent: changes made early are cheap, and changes made late are expensive.

Changing the orientation of a house during schematic design costs a few hours of work. Changing it after construction documents are complete means redrawing most of the permit set. This is not a reason to avoid revisions. It's a reason to engage seriously and early, when the design is still fluid and your feedback has the most leverage.

The most common costly revision pattern is the client who says "looks good" at every check-in and then surfaces major concerns when the permit drawings are nearly done. If something doesn't feel right, say so as soon as you notice it. Your designer would rather hear it in week three than week fifteen.

It also helps to distinguish between "I'm not sure about this yet" and "this is definitely wrong." Both are useful, and they call for different responses. The first might mean you need to sit with a design longer before judging it. The second means it needs to change.

Stay involved, but let the designer drive
You'll hear advice to "stay involved" in your design project, and it's good advice. But there's a version of staying involved that actually slows things down: second guessing every decision, requesting updates before there's anything meaningful to show, or bringing in new opinions mid-process after the design direction has already been set.

The most useful involvement is front loaded. It happens at the beginning of each design phase, when you're reviewing concepts and giving feedback while things are still easy to change. It happens when you're asked to make decisions about things that matter to you: which rooms face the view, how the entry works, what the relationship between the kitchen and the outdoor space looks like.

The less useful involvement is the kind that happens in the middle of a work phase, when your designer is in the weeds of developing something based on decisions already made together. Letting that work happen, and then reviewing it seriously when it's ready, produces better results than checking in constantly.

Design projects also tend to go sideways when too many people get a vote. If you're building with a partner, align on priorities before you walk into a meeting, not during it. If you're getting input from family or friends, be clear about whose input actually drives decisions. A designer can't reconcile five competing visions. One or two decision-makers, with clear authority, works much better.

The short version
​The best design projects tend to share a few things: an honest budget conversation that happened early, a client who brought real site constraints to the table, and a working relationship where both sides felt comfortable saying what they actually thought.
​
None of that requires a complete vision or years of planning. It just requires treating the working relationship as part of the project, not an afterthought to it. If you're thinking about starting a design project in Kittitas County and want to talk through what that process looks like, feel free to reach out.

The clean, contemporary lines with rustic materials and accents, make for a beautiful home.

Let's face it, it's 2023, not 1973, so I don't get much call for A-Frames these days. However, I received a request for one recently, and it's been fun project to model.