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ADU Design & Approvals Cost Calculator for Reno
Design is the one stage this site does not publish a price table for — it is quoted after seeing the property. So this calculator is built from independent 2026 figures and says so plainly, then shows you the share of your build it represents.
Why your estimate is what it is
What drives adu design costs in Reno
Design and approvals is not one fee, it is six or seven separate things bought from different people, and the confusion comes from proposals that bundle them differently. Architectural drawings are one line. Structural engineering is another, and in Washoe County it is a bigger line than most people expect because the snow load sizes the roof. Then there is the survey, sometimes a soils report, an energy compliance calculation, and finally the permit and plan-check fees — which are paid to the city or the county, not to the designer, and which belong in a different column of your spreadsheet.
The convention is a percentage, and it is worth knowing why
Design is conventionally quoted at 10 to 15 percent of construction cost, and independent 2026 figures put it there. That is not because drawing a big building takes proportionally longer — it is because a bigger building carries more risk, more coordination and more consultants. On a small, cheap project the percentage rises, because the survey, the energy calculation and the permit fee cost roughly the same whether the unit is 400 square feet or 1,000. Do not be alarmed by a high percentage on a small build; be alarmed by a low percentage on a complicated one.
Elevation decides how much engineering you are buying
Washoe County sets the design ground snow load by elevation, west of US 395 and Risk Category II: about 43 psf below 5,000 feet, 59 psf at 5,100, 92 psf at 5,300, and 203 psf at 6,000. That is a fivefold difference in what the roof has to carry, and it is not something an engineer adjusts at the end — it sizes the members, the connections and the walls under them, and it feeds back into the architecture. A designer who has not asked your elevation has not started thinking about your roof.
Which counter you are standing at changes the fee and the timeline
Reno and Sparks are cities with their own building departments. Spanish Springs, Sun Valley, Lemmon Valley, Golden Valley and much of the outlying area are unincorporated Washoe County, with a different counter and a different fee schedule. Incline Village sits inside the Tahoe Regional Planning Agency area, which is a materially different and longer process. Plenty of addresses that say Reno in the mail are county parcels. Confirm which one you are in before anyone quotes you.
What could push your price higher
- An architect-led process with concept options explored before the permit set begins
- A property above about 5,300 feet, where the structural scope grows with the snow load
- A sloped lot, which turns a survey and a soils report from optional into required and adds a civil and grading plan
- Building over an existing garage, which always needs the structure underneath engineered
- A brief that is still moving after the permit drawings have started
- A property inside the TRPA area at Incline Village, with its own review, coverage rules and season-length timeline
What could bring it down
- Using a stock or pre-approved plan as drawn, which removes the single largest line
- Already owning a current survey — the most useful document to have in hand
- A flat, rectangular lot on the valley floor with utilities close to the house
- As-built drawings of the existing house, if you are converting a garage or building an attached unit
- A settled brief, signed off in writing before the permit set starts
- Buying design in phases — concept, then permit drawings — with a decision point in between
Turn the estimate into a real number
This calculator works from the 2026 cost figures published on this site for Reno. What it cannot see is your soil, your slope, how far your utility connections actually run, or what your lot and your HOA will allow. We will come out, walk the property and give you a written scope with no pressure attached.
Book a free consultationFrequently asked questions
Why does this calculator not use figures published on this site?
Because this site does not publish any for design. Every other calculator here is anchored to the price tables on our own service pages. The ADU design page deliberately sets out scope and cost factors rather than numbers, and says estimates are provided after understanding the project. Rather than invent a table, this calculator is built from independent 2026 sources — design fees at 10 to 15 percent of project cost, architecture at $6,000 to $25,000 and up in Nevada, engineering at $2,000 to $9,000, and permits and plan check at $3,000 to $18,000 and up — and tells you which of those it is using.
Do I need an architect, or will a designer do?
Nevada does not require an architect's stamp on every residential project, and a great deal of competent ADU work is drawn by residential designers. What you cannot skip is a licensed structural engineer where the structure needs one, which in this region is most detached units and every unit built over an existing garage. The practical question is not the title on the business card but whether the person has taken an ADU through your specific building department before. Ask for two recent addresses and check they were in your jurisdiction.
How long does the permit take in Reno?
Independent northern Nevada sources put ADU permit timelines at roughly three to six months, and that is time before anyone breaks ground rather than in addition to construction. The variables are the completeness of the submission, whether plan check comes back with corrections, and how busy the department is. The single largest thing within your control is submitting a complete set the first time, which is what you are paying a designer for. Confirm current timelines with the City of Reno or Washoe County directly.
Are permit fees included in a design fee?
They should never be silently included, and they are shown separately in this calculator for that reason. Permit and plan-check fees are paid to the jurisdiction. When you compare two design proposals, check whether each one includes them, excludes them, or passes them through — otherwise you are comparing different things. Jurisdiction fee schedules also change on their own timetable, so treat any figure here as an order of magnitude and confirm the current one.
What does AB 396 change about design?
Nevada's AB 396 was approved on 6 June 2025 and its ADU provisions take effect on 1 July 2026, covering counties over 100,000 — Washoe included — and cities over 60,000, which covers Reno and Sparks. From that date a local ordinance may not ban a separate kitchen, require more than one parking space, impose side or rear setbacks stricter than the primary residence, or prohibit long-term rental. For design that removes several constraints that used to shape the drawings. Two things it does not touch: properties inside the Tahoe Regional Planning Agency area, which includes Incline Village, and private HOA covenants, which can still block an ADU outright.
Can I reuse a plan from another state?
Partly. The layout usually travels; the structure does not. A plan drawn for a mild climate will not carry Washoe County's snow load, will not account for a 24-inch frost depth, and will not satisfy Seismic Design Category D2 or a 120 mph design wind speed. Expect to buy local structural engineering, a local site plan and an energy compliance calculation on top of whatever the plan cost. That combination is exactly what the modified stock plan option in this calculator prices.
Related calculators
Planning the whole project? Start at the Reno ADU calculator hub, or read more about our ADU design service.