Frequently Asked Questions
We design backyard cottages two ways: pre-approved plans that move quickly through Seattle's permit process, and custom designs for lots and ideas a standard plan doesn't fit. If you're not sure which is right for you, send us your address and we'll tell you.
Which path is right for me?
Pre-approved plan
Best for typical Seattle backyards, and for owners or builders who want to move fast.
Design fee: a $1,000 plan license, plus site-specific permit work billed hourly.
City permit review: usually 2–6 weeks for qualifying lots.
Changes: small site-fit adjustments only.
Lot requirements: a Neighborhood Residential zone, no environmentally critical areas, and less than 750 square feet of ground disturbance.
Custom design
Best for unusual lots, specific needs, or a cottage that's entirely your own.
Design fee: capped at 10% of the total project budget, with a not-to-exceed amount for each phase.
City permit review: standard review, usually several months.
Changes: designed around you from the start.
Lot requirements: any lot where a cottage is allowed.
Many custom projects start from one of our pre-approved designs and grow from there.
Questions for everyone
I'm interested. What's the next step?
Get in touch and send us your address or site information. We'll check whether a cottage fits your lot and meets the City's current rules, and recommend a path. We can also provide preliminary drawings and images free of charge, so your builder can give you a rough cost estimate. If you don't have a builder yet, we can connect you with builders we've worked with.
What if a design doesn't fit my site?
Our pre-approved designs are sized for small and medium backyard lots, and small adjustments often make them fit. If yours needs more than that, a custom design is the better path. Either way, we'll tell you before you commit to anything.
How much does it cost to build?
For budgeting, plan on roughly $500 to $600 per square foot for construction, not counting design and permit fees. One of our recent projects came in around $450 per square foot. Your number depends on your site, finishes, and builder, so get a contractor's price early.
What will I pay other people?
Some costs go directly to the City, utilities, and consultants. Depending on your lot, these can include:
City permit fees, based on project size and value. The City publishes a fee estimator and fee schedule.
A King County sewer capacity charge for new dwelling units. You sign an acknowledgment form when you apply.
Utility connections, including any new or upgraded electrical service from Seattle City Light.
A survey, if the cottage sits close to a setback or property line.
Structural, geotechnical, or civil engineering, if your site needs it.
An arborist report, if there are large trees near the building.
Do you build the cottage?
No. We design and permit, and you hire the builder. Any licensed contractor can build from our drawings, and bringing one in early helps keep the project on budget.
I'm a builder or developer. Can I use your designs on more than one lot?
Yes. Each lot needs its own plan license; ask us about pricing for several lots.
How do people pay for a backyard cottage?
Most owners use savings, a home equity loan or line of credit, or a construction loan.
Can I rent the cottage out?
Yes. Long-term rentals in Seattle must be registered under the City's rental registration program, and short-term rentals have their own rules.
How long is a permit good for?
A Seattle building permit typically expires 18 months after it's issued, and it can be renewed or reestablished for an added fee. Seattle also updates its building codes on a regular cycle; the current 2021 Seattle codes took effect November 15, 2024. If the code changes before you apply, your drawings may need updating, and we can tell you whether yours do.
Where can I read the City's rules?
Start with the City's accessory dwelling unit page, which links to the code and the City's guides. The ADUniverse site has a tool for checking whether a cottage could fit on your property. For questions about your specific lot, the City has an online question form.
Can I get a refund?
All sales of our copyrighted plans are final, and we can't offer refunds or exchanges once you've received them. Before you buy, we strongly recommend getting a preliminary bid from your builder, and we're happy to help with that.
Pre-approved plans
The City of Seattle has selected our designs as pre-approved standard plans. Because the City has already reviewed them, permits for qualifying lots move much faster.
What is a pre-approved plan?
It's a backyard cottage design the City has already reviewed for structural code. Only the parts specific to your site still need review, so the City says most permits are issued in 2–6 weeks. You can browse every pre-approved design in the City's ADUniverse gallery.
Which ahouse designs are pre-approved?
Currently, the family is pre-approved in two cities, in slightly different versions:
Seattle: a two-story cottage with 1.5 baths, 808 square feet with one bedroom or 964 square feet with two. Its 30 foot by 17 foot 8 inch footprint fits lots as narrow as 30 feet. The City selected it when it launched its pre-approved program in 2020.
Kirkland: a larger, 1,132 square foot version with [X bedrooms and X baths], pre-approved for streamlined permitting in Kirkland.
Seattle chooses pre-approved plans through design competitions. In 2026, we won its latest competition, which expands the program beyond backyard cottages to single-family homes and duplexes. Our winning design is a single-family home that can also be mirrored to form a duplex. We'll add it here once it's available to use.
What does it cost?
Plan license: $1,000. This covers use of the pre-approved design on one lot.
Permit documents: billed hourly. This covers site evaluation, the site plan, any site-specific engineering, and permit paperwork.
Changes and extra services: billed hourly. This covers changes you request, site visits during construction, and responses to City corrections.
We'll give you an estimate for the hourly work before we start.
Does every lot qualify for the fast track?
No. Under the City's current rules, the project must:
Sit in a Neighborhood Residential zone (NR)
Have no environmentally critical areas on the property, such as steep slopes or wetlands.
Disturb less than 750 square feet of ground in total, including the cottage and any driveway.
A lot that doesn't qualify can still use our design through the City's standard review, which takes longer. At that point, a custom design is often worth considering.
How does the process work?
Check your lot with us, or with the City's ADUniverse tool.
Choose a design and license it.
We evaluate your site and prepare the site plan and permit documents.
You or we apply through the Seattle Services Portal, following the City's step-by-step guide.
The City reviews the site-specific parts and issues the permit.
Your builder constructs the cottage, with City inspections along the way.
Can I change the plan?
Small adjustments to fit your lot, like mirroring the plan or shifting a door or window, are included at no added cost. We can also adjust window area for your lot's orientation or your budget. Larger changes to the structure or layout mean the plan is no longer the pre-approved version, so the project moves to custom design and standard City review.
Who handles corrections from the City?
Corrections to our architectural drawings are included. Responses to City corrections are billed hourly. Depending on your site, you may also need a structural or civil engineer for site-specific items such as foundations or drainage. We can guide you through the permit process, or you and your builder can take it on yourselves.
Can I build one of your designs outside Seattle?
Yes. Outside Seattle the plan isn't pre-approved, so it goes through that city's or county's normal review. We can adapt the drawings to local requirements.
Custom design
For steep or narrow lots, sites with large trees, a specific program, or simply a cottage of your own, we offer full design services from first sketch to permit.
When does custom design make sense?
Your lot doesn't qualify for the fast track, such as a steep slope or other critical area.
A pre-approved design almost works, but you need more than small adjustments.
You want a different size, layout, or use, like a studio, office, or accessible home for a family member.
You're planning more than one unit, or a cottage with a garage or workshop.
What does the process look like?
Site and feasibility: we study your lot, the zoning, and what the City allows, and confirm what you want to build.
Schematic design: we develop design options and settle on a direction with you.
Design development: we refine the plan, materials, and details, and coordinate with your builder on cost.
Permit set: we prepare the drawings for the City and coordinate with engineers.
Permit and construction support: we respond to City corrections and answer your builder's questions during construction.
How do you charge for custom design?
Our custom design fee is capped at 10% of your total project budget. We divide that amount across the design phases as not-to-exceed fees, so you know the most each phase will cost before it starts. Most projects come in under the cap. We’ll send you a proposal with the phase amounts once we’ve seen your site and talked through your goals.
How long does it take?
Design usually takes 8 to 12 weeks, depending on how quickly decisions are made. City review for a custom cottage is longer than the fast track; see the City's permit timeline information for current review times.
Can I start from one of your pre-approved designs?
Yes, and it's often the most economical way to go custom. Starting from a design we know well saves design time, even when the result needs full City review.
What do you need from me?
Your address, a sense of how you'll use the cottage, your budget, and any survey or site information you already have.
The a-frame
Is the a-frame a backyard cottage?
No. The a-frame is a separate, 120 square foot design for an off-grid cabin or a backyard play structure. It isn't a pre-approved Seattle DADU. Permit rules for small structures depend on size, use, utilities, and foundation, so check the City's Do You Need a Permit? page or your local building department before you build. Meeting local requirements is the owner's responsibility.
Still have a question?
Send us your address and what you're hoping to build, and we'll help you find the right path. Contact us.
City of Seattle information on this page was checked in October 2026. Rules and fees change, so confirm current requirements with the City before you build.
Last updated October 2026. This page is general information and is subject to change without notice. Our fees, billing, and services may change, and the terms of your project are set by your proposal or contract with us, not by this page. City rules, fees, and building codes also change, including the City’s upcoming code update. Before you build, confirm current requirements with the City of Seattle or your local building department.