Short answer: a lot inside the City of Woodinville in a single-family zone allows a house up to 35 feet tall, set 10 feet from the street and 5 feet from the side and rear lines. A lot outside the city limits follows King County’s Title 21A instead, so settle which side of the line you are on before anyone draws.

How I work here is on my Woodinville architect page. City figures come from Title 21 of the Woodinville Municipal Code, current through Ordinance 811 (August 4, 2026), and county figures from King County Code Title 21A, updated September 9, 2026. Confirm a number before relying on it. See also my Redmond, Issaquah and Kirkland guides.

City or county: whose rules apply

Do not assume from your mailing address. King County tells owners to confirm that a parcel is in unincorporated King County, outside city limits, before relying on zoning. I make three checks:

• Jurisdiction. Look up the parcel in the county’s parcel viewer or iMap, or in the Assessor’s property detail, where parcel data confirms jurisdiction and land data lists zoning. If the parcel sits outside King County, this guide does not cover it; ask the county that holds it.
• City zone. The official map is the one adopted by Ordinance 738 and its amendments (WMC 21.20.020). A GIS zoning layer is a handy guide, but the adopted map controls.
• County zone. Outside the city and inside King County, the Assessor’s land data and the county’s parcel reports list the zone, such as RA-5 or A-10, and King County Permits issues the permit.

The city’s single-family zones and the zoning map

R-1 is for large-lot neighborhoods in the northeastern forested part of the city, R-4 for suburban-size lots with environmental limits, and R-6 and R-8 for more common urban lot sizes (WMC 21.20.030). A house or a duplex is permitted in all four (WMC 21.21.050).

Source: WMC Tables 21.31.030, 21.32.030(2) and 21.32.040(2). The garage yard is measured along the driveway from the garage door to the street line. The code lists street and interior lines only, so I read the rear as interior.

Roof coverage, yards and height in the city

The city’s residential zone tables set no impervious surface percentage and no floor area ratio (the shoreline overlay does, below). They cap building coverage, which is the area under roofs (WMC 21.11A.030), and require a minimum share of the lot in landscaping, which excludes pervious pavement. The caps fall as lots grow:

Source: WMC Table 21.32.050(1).

Height. Measure from average finished grade, taken 6 feet out from the walls at the midpoints of the sides of the smallest rectangle that encloses the house, to the coping of a flat roof or the average height of the highest triangle of a gable or hip roof. Berms built to raise the average do not count (WMC 21.32.040(5)). A pitched roof may rise up to 10 feet above the 35 foot limit if the space under it is an attic or opens to rooms below, at a pitch no steeper than 1 in 2. Chimneys are exempt (WMC 21.32.040(6)).

Two lots, worked through

An R-4 lot, 80 by 150 feet (12,000 square feet).

• Roof cap: 12,000 x 0.35 = 4,200 square feet.
• Building zone: 80 to 10 = 70 feet wide by 150 to 10, 5 = 135 deep, or 9,450 square feet. The 4,200 cap is 44 percent of that, so the coverage cap sizes the footprint.
• Trees: 12,000 / 43,560 = 0.2755 acre x 50 credits = 13.8 credits.

An R-1 lot of exactly one acre (43,560 square feet).

• Roof cap at 15 percent: 6,534 square feet. A lot one square foot smaller falls in the 20 percent band: 43,559 x 0.20 = 8,712. That is 2,178 square feet less roof.
• Landscaping at 75 percent is 32,670 square feet, so roofs and all hard surface share 25 percent, or 10,890. Roofs at the cap use 6,534, leaving 4,356 for driveway, terraces and pool deck.
• Trees: 1 acre x 70 credits = 70 credits. Twelve retained trees of 24 to 35.9 inches at 6 credits each give 72.

If your parcel is in unincorporated King County

The rural table is K.C.C. 21A.09T.030. Rural zones use bigger lots and an impervious cap instead of roof coverage:

Source: K.C.C. 21A.09T.030, updated September 9, 2026. Lots of 1 to 2.5 acres use R-1 yards and lots under 1 acre use R-4 yards. A lot of one-half acre or more may have at least 10,000 square feet of impervious surface. An RA-zoned residence must sit 100 feet from a line shared with A, M or F zoned land, (lots under 150 feet wide use a share of their width).

On a 5 acre RA-5 lot (217,800 square feet), 20 percent is 43,560 square feet of impervious surface, exactly one acre. The county measures height from average finished grade, found the same way as in the city, to the highest point of the roof (K.C.C. 21A.12.050), so a gable is measured to its peak there but to the average height of its triangle in Woodinville.

Farmland. In the A zones, a house is allowed only as a farm residence accessory to active, ongoing agriculture, sited on the part of the land least suited to farming (K.C.C. 21A.08.030, condition 17).

Clearing and grading. The county requires a clearing permit above 7,000 square feet on RA-zoned land and a grading permit at 100 cubic yards, 2,000 square feet of new impervious surface, or any grading around a critical area.

Streams, wetlands and steep slopes

The city’s critical areas map is a guide; a site investigation decides what is there (WMC 21.51.030). Remodels and repairs need no critical area review if they add no footprint inside a critical area or buffer and no significant risk (WMC 21.51.040(6)).

• Streams. Fish-bearing streams carry a 200 foot riparian zone, 150 feet if it is mostly native planting. Other streams carry 100 feet (WMC 21.51.120(6)).
• Wetlands. Standard buffers run 50 to 300 feet by category and habitat score, and reduced widths with mitigation measures start at 40 feet (WMC 21.51.100(7)). Buildings stay 10 feet back from a stream zone or wetland buffer (WMC 21.51.050(3)).
• Steep slopes. A slope of 40 percent or more with 10 feet of relief takes a buffer of its height or 50 feet, whichever is greater, reducible to 10 feet with professional support, plus a geotechnical report (WMC 21.51.110).
• New construction. New construction, or a reconstruction costing 50 percent or more of the structure’s market value, puts wetlands, buffers and most habitat areas (Type S streams excepted) into a protected tract (WMC 21.51.050(5)).

In the county, riparian areas run 200 feet from Type S or F (fish-bearing) streams outside the urban growth area, 180 inside it, and 100 feet from Type N streams. Structures stay 10 feet back, and a steep slope buffer is 50 feet if no geologic report sets it (K.C.C. 21A.24.358, .200, .285). An existing house may grow into a buffer only on existing lawn, landscaping or paving, with the least impact, by no more than 1,000 square feet of footprint cumulatively since January 1, 2005 (K.C.C. 21A.24.045).

The Sammamish River and Little Bear Creek

The city’s shoreline jurisdiction covers both waters and 200 feet landward of the ordinary high water mark, plus floodways and the floodplain within 200 feet of them (WMC 21.70.050).

• A detached house is prohibited in the Conservancy environment, which is the first 100 feet landward, and in Urban Conservancy. It is permitted in the Residential and Urban General environments beyond that (WMC 21.71, 21.72.030).
• Both are Type S streams: a 150 foot standard buffer, or 100 feet with enhancement where the buffer is degraded and the lot is in the Residential or Urban General environment (WMC 21.77.120(6)).
• Height is 35 feet above the average natural or existing grade under the building; the finished grade used elsewhere does not apply (WMC 21.74.030, 21.70.210, 21.70.217).
• Impervious surface in the Residential environment is capped at 50 percent along the Sammamish River and 30 percent along Little Bear Creek, counted on lot area inside shoreline jurisdiction (WMC 21.74.020).

A shoreline exemption is a Type 1 decision; see my shoreline exemption guide. A shoreline lot outside any city follows the county’s chapter 21A.25.

Trees

A project that needs a construction permit also needs a tree permit, unless the remodel removes no trees and does not alter or expand the footprint, with tree protection in place (WMC 21.50.030, 21.50.050). The permit needs an arborist report and a tree site plan.

• Density. You must meet 70 tree credits per acre in R-1 and 50 per acre in R-4 to R-8, counted on lot area outside the right-of-way (WMC 21.50.060). A retained tree earns from 0.5 credit at 2 inches across to 8 credits at 36 inches or more.
• Shortfall. If you cannot plant the difference, you pay $500 per credit into the City Tree Fund (WMC 21.50.100). A 10 credit gap is $5,000.

Remodel, rebuild or tear down

A legal nonconforming house in the city may be repaired, remodeled or enlarged if the work does not increase the nonconformance and adds no bulk or area to the parts that cause it (WMC 21.14.050). It loses that protection on substantial destruction: removing more than 50 percent of the exterior wall framing, measured by horizontal length, where partial removal counts as removing the whole segment (WMC 21.11A.200, 21.14.050). On 240 feet of wall, 120 feet is the limit; anything more crosses it. After that the whole structure must meet current rules. If a fire or other casualty you did not cause destroys a house, you may rebuild the original configuration if you file a complete application within 3 years.

On the shoreline the test is more than 60 percent of the exterior walls, framing and foundations included (WMC 21.70.228, 21.73.080). In a mapped flood zone with a base flood elevation, a remodel costing 50 percent or more of the structure’s market value is a substantial improvement, and the lowest floor, basement included, must sit at least 1 foot above the base flood elevation (WMC 21.53.050, 21.53.140).

In the county, a nonconforming structure may be modified if the change does not expand the nonconformance, and an expansion of building area, impervious surface or height can be approved up to 10 percent (K.C.C. 21A.32.055, .065). A damaged or destroyed structure may be rebuilt without expansion on a complete application within 12 months (K.C.C. 21A.32.045). That section does not mention a house you demolish yourself, so plan a teardown to current standards and confirm with the county. Other cities draw this line differently; see my Eastside comparison.

ADUs

The city allows up to 2 ADUs per lot in R-1 through R-18, each 300 to 1,500 square feet of habitable floor area. An ADU counts toward the units per lot, except that the second of two does not (WMC 21.41.020). Each full 43,560 square feet over the R-1 minimum adds one unit, so 78,560 square feet allows 3 (WMC 21.31.030).

The permit: who reviews and how long

In the city, the Building Official decides the building permit, a Type 1 decision. The Director decides critical area, tree and shoreline exemption permits (WMC 21.80.050). Staff must tell you within 28 days whether the application is complete. The code sets a 65 day clock for Type 1 decisions and a 120 day outer limit for construction permits, both counted from that completeness decision, with the clock stopped while you answer the city’s questions (WMC 21.80.100, 21.80.210). I would plan on the longer figure and ask the city which one applies to your permit. A complete building permit application vests you to the rules in effect that day (WMC 21.80.080). In the county, King County Permits reviews, and MyBuildingPermit.com lists the application steps.

Washington law does not require an architect for a house (RCW 18.08.410), but a lot with a stream, slope or stand of firs rewards doing the survey, critical areas work, geotech and arborist first. Piper Cole designs and administers construction on your behalf and does not build. I have been an architect since 1996, an AIA member since 1992 and an NCARB member since 1996.

Questions