The short answer
What to check before landscaping a Seattle backyard
Start a Seattle backyard with the water and the trees. In parts of the city, downspouts feed the combined sewer, the old pipes that carry rain and sewage together. In those RainWise areas, Seattle Public Utilities and King County rebate up to $13.12 per square foot of roof drained to a rain garden and $9.91 for a cistern. Outside environmentally critical areas, SDCI usually requires no permit for patios on grade, open-framed arbors up to 120 square feet or fences under 8 feet. More than 750 square feet of new or replaced hard surface on a permitted project brings stormwater review. Trees 6 inches and wider are protected by the city's tree code.
Before designing anything, enter the address on the RainWise map. In eligible areas the rebate is up to $13.12 per square foot of roof drained to a rain garden, and the program says rebates cover 90 to 100 percent of an installation.
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Refresh the yard: inclusions & limits
Patio slabs on grade and walks less than 18 inches above grade need no SDCI permit, and neither do fences under 8 feet with no concrete or masonry above 6 feet, unless the lot is in an environmentally critical area. On a developed Neighborhood Residential lot, owners may remove only two Tier 4 trees, 6 to 12 inches across, in any three years without SDCI review, and paid pruning of live roots 2 inches or thicker counts as reportable tree work.
Replan the outdoor space: inclusions & limits
On a permitted project, adding or replacing more than 750 square feet of hard surface, or disturbing more than 5,000 square feet of land, triggers SDCI stormwater review. RainWise adds a second track: the property must be in a mapped area and connected to the combined sewer, a RainWise-trained contractor designs the system, installations must manage at least 50 percent of the roof water, and owners maintain them for five years.
Add a covered space: inclusions & limits
Open-framed arbors up to 120 square feet skip the permit, and covered areas count toward the 50 percent lot coverage cap in Neighborhood Residential zones. Decks more than 18 inches above ground need a permit, usually the quicker STFI kind. Inside Seattle, a gas line to a grill or fire feature must be installed by the owner or a holder of a Seattle Gas Piping Mechanic License, and new wiring needs an SDCI electrical permit.
What an outdoor living project costs in Seattle in 2026.
Patios on grade, planting and open arbors up to 120 square feet need no SDCI permit in most of Seattle, so the city's permit records mainly show the heavy end of backyard work: retaining walls. On 104 outdoor permits SDCI took in for single-family homes and duplexes since September 2024, 90 of them for retaining walls, owners declared a median of $24,500, and half landed between $15,000 and $50,000.
$24,500
RainWise changes the math where it applies. In mapped areas where downspouts reach the combined sewer, Seattle Public Utilities and King County rebate up to $13.12 per square foot of roof drained to a rain garden and $9.91 for a cistern, and the program's own example, a 1,245 square foot roof, earns $16,334 for a rain garden that takes all of it. The program says rebates cover 90 to 100 percent of an installation. For scale, the Census Bureau's survey puts the average Seattle-area landscaping or sprinkler project at $4,007, far below a permitted wall.
All the numbers and where they come from
| Figure | Value | What it measures |
|---|---|---|
| Median permit value | $24,500 | Declared project cost on 104 outdoor building permits for single-family homes and duplexes, filed September 2024 to September 2026; 90 of them are retaining walls, with a median of $25,000. Half fall between $15,000 and $50,000. (Seattle SDCI building permits, open data) |
| Top tenth of permits | $100,000+ | One in ten of those permits declared $100,000 or more. (Seattle SDCI building permits, open data) |
| RainWise rain garden rebate | Up to $13.12 a sq ft | Per square foot of roof area drained to a rain garden, in eligible areas on the combined sewer. Cisterns earn up to $9.91. Paid by check 4 to 8 weeks after the paperwork. (RainWise, Rebate Process) |
| RainWise example | $16,334 | The program's worked example: a 1,245 square foot roof drained entirely to a rain garden. Two cisterns capturing the same roof earn $12,093. (RainWise, Rebate Process) |
| Seattle-area landscaping average | $4,007 | Mean spent on landscaping or sprinkler projects in the Seattle-Tacoma-Bellevue metro in 2023, DIY included (margin of error $1,383). The survey does not publish a metro median for this category. (U.S. Census Bureau, American Housing Survey 2023, Table 16) |
| Landscaping worker wage | $23.31 an hour | Median wage for landscaping and groundskeeping workers in the Seattle-Tacoma-Bellevue metro, May 2025. Construction laborers earned a median $28.72. Contractors bill above wages. (U.S. Bureau of Labor Statistics, May 2025 wages, Seattle-Tacoma-Bellevue) |
| Budget line | Define it | Watch for |
|---|---|---|
| RainWise rebate | Up to $13.12 per square foot of roof area for rain gardens and $9.91 for cisterns, paid by check 4 to 8 weeks after the paperwork. The program says rebates cover 90 to 100 percent of an installation. | Gutter repair is not rebated, and extras like rerouted pipe or removing a whole patio may not be covered. Some contractors offer a vendor payment option. |
| Stormwater and grading | Base, drainage and any stormwater review on a permitted project. Work with 5,000 square feet or more of new plus replaced hard surface needs a drainage report from a licensed civil engineer. | Stormwater review starts above 750 square feet of new or replaced hard surface, so ask each bidder to state the total. |
| Trees | Arborist assessment, protection during construction and any replacement planting. SDCI's tree protection area starts as a radius of one foot for every inch of trunk diameter. | SDCI warns that penalties for unlawful tree removal can be expensive. Ask where footings and trenches fall relative to each protection area. |
For inclusions, allowances and exclusions, see how to read a contractor quote line by line. For broader benchmarks, see the Renology Cost Index.
What an outdoor living project budget buys in Seattle.
About $4,000
The average Seattle-area landscaping or sprinkler project, $4,007 in the Census survey. New planting, surfaces and lighting on the existing layout usually need no permit, but the tree rules still apply. On a developed Neighborhood Residential lot, owners may remove only two Tier 4 trees, the smallest protected size at 6 to 12 inches across, in any three years without SDCI review.
$15,000 to $25,000
From the bottom quarter of outdoor permits to the median, nearly all of it retaining walls. Walls and rockeries up to 4 feet, measured from the bottom of the footing, usually skip the permit, so the walls in these records tend to be the ones that cross that line. A RainWise rain garden can land in this range too, largely paid back: $16,334 in the program's example.
$50,000
Where the top quarter of permits begins, with descriptions such as site improvements built around a new retaining wall. On a permitted project, adding or replacing more than 750 square feet of hard surface triggers SDCI stormwater review. At 5,000 square feet of new plus replaced hard surface, the drainage report has to come from a licensed civil engineer.
$100,000 and up
The top tenth of permits. Descriptions here read like whole-site projects, such as one filed at $120,000 for retaining walls, patios, walkways and stairs. Covers and outdoor kitchens join the list at this level. Covered areas count toward the 50 percent lot coverage cap, a gas line needs the owner or a Seattle licensed gas piping mechanic, and new wiring needs an SDCI electrical permit.
What a Seattle retaining wall permit says about a backyard budget.
Ninety of the 104 outdoor permits in Seattle's records are retaining walls, so the $24,500 median is mostly the price of a wall. Planting, patios on grade and fences under 8 feet need no permit and are not in it. A landscape bid covers excavation, drainage, materials, labor, overhead and margin, plus a cushion for what the digging finds.
Compare the bids on what they protect and what they pay back. One may include an arborist's assessment and tree protection areas sized at one foot of radius for every inch of trunk. It may measure hard surface against the 750 square foot line, use a RainWise-trained designer and name licensed installers for gas and power. Another may leave out what RainWise does not pay for, such as gutter repair, extra pipe or removing a whole patio. Several trades bill on one job: landscaping workers in the Seattle-Tacoma-Bellevue metro earned a median $23.31 an hour in May 2025, construction laborers $28.72 and electricians $48.93.
Bring the bid checklist to every contractor so the numbers describe the same job.
Make the guide yours
Refresh, replan or add a cover in a Seattle yard?
A Seattle yard refresh can stay clear of permits but not of the tree rules, which cap how many small trees an owner may take out and treat paid root pruning as reportable work. Replanning the yard brings the 750 square foot stormwater line and, in RainWise areas, a rebate. A cover or outdoor kitchen brings lot coverage, gas licenses and electrical permits.
No scope selected. The guide and checklist are available without choosing a project tier or leaving contact details.
A covered space still needs a water plan
A new patio cover is a small roof, and its water has to land somewhere other than the walkway. On a permitted project, adding or replacing more than 750 square feet of hard surface triggers SDCI stormwater review, and a roof counts as hard surface. Draw where the cover's downspout drains before sizing the cover.
A solid cover does not fit SDCI's exemption for open-framed arbors up to 120 square feet, so it needs SDCI review. It also counts toward the 50 percent lot coverage cap in Neighborhood Residential zones.
Official starting point: Seattle SDCI permit resources.
A decision to work through · illustrative scenario
A solid cover over the back patio
The owners want a roofed cover over the patio by the back door. It falls outside the open-arbor exemption, counts toward lot coverage and needs a place for its downspout that is not the walkway.
Before you compare bids: Ask for the cover's size against the 50 percent lot coverage cap, the footing or house attachment detail, and where its downspout drains.
Water, trees, then structures: the order for a Seattle backyard
Seattle backyard projects go wrong in the order of work more often than in the choice of plants. Water and trees come first because RainWise eligibility and tree protection areas shape everything drawn afterward. Then the design is checked against the city's numeric triggers, and only then does paving start. A RainWise job adds inspections before and after construction.
- 1
Map water and trees. Enter the address on the RainWise eligibility map, note where each downspout goes, and measure trees 4.5 feet above ground. Check SDCI's GIS map for environmentally critical areas, which can remove the usual permit exemptions.
- 2
Design around the triggers. Track hard surface against the 750 square foot stormwater line, retaining walls against 4 feet and structures against the 120 square foot arbor limit. If RainWise applies, the trained contractor sizes the rain garden or cistern and calculates the rebate before work starts.
- 3
Build from the ground up. Underground lines and drainage go in before paving, then structures, then planting. A RainWise project runs through a pre-inspection, construction and a post-inspection, and the rebate check follows 4 to 8 weeks after the paperwork is submitted.
Ask for separate dates for design, permit review, ordering and construction.
The site facts a Seattle landscape bid should start from
Landscape bids in Seattle often start from a sketch of plants and pavers. Ask instead for the facts the city and the utilities will look at. That means RainWise eligibility, trees 6 inches and wider, hard surface against the 750 square foot line, structure heights and sizes, and who holds the gas and power licenses. Two bids built on the same facts can be compared.
- The RainWise eligibility result for the address, and whether the downspouts reach the combined sewer.
- A site plan showing trees 6 inches and wider at 4.5 feet, with their protection areas.
- Total new and replaced hard surface, measured against SDCI's 750 square foot trigger.
- Heights and sizes of every wall, deck and structure, since 4 feet, 18 inches and 120 square feet decide permits.
- Gas and electrical scope, with the licensed installer named for each.
If you ask for help, a Renology advisor talks through your scope and checks local contractor availability. You decide whether to go ahead.
Already have a proposal? Check its scope and exclusions with the quote-review tool before your next contractor conversation.
RainWise, rain barrels and patio covers in Seattle
RainWise is the Seattle backyard program people search for by name. The questions below start with the cover over the patio, then turn to cost, who qualifies for RainWise, cisterns and when a patio cover needs a permit.
Does a patio cover change the drainage plan?
Yes. A cover collects rain that used to spread across the patio and sends it to one gutter and one downspout. Plan where that water lands before sizing the cover, and count the cover in the hard surface total SDCI measures against its 750 square foot stormwater line.
How much does it cost to landscape a backyard in Seattle?
SDCI took in 104 outdoor permits for Seattle single-family homes and duplexes since September 2024, 90 of them for retaining walls. Owners declared a median project cost of $24,500, with half between $15,000 and $50,000. Planting and patios on grade mostly need no permit, and the average Seattle-area landscaping or sprinkler project in the Census survey was $4,007. In eligible areas a RainWise rain garden can earn back $16,334, as in the program's own example.
Who is eligible for RainWise rebates in Seattle?
There are three tests. The property sits in a RainWise-eligible area on the program's map, its roof water reaches the combined sewer, which staff confirm from an eligibility form, and a contractor finds a rain garden or cistern feasible. Lots with poorly draining soil, steep slopes or landslide risk may qualify only for a cistern. Properties that miss out may qualify for a GSI (green stormwater infrastructure) Mini-Grant through Stewardship Partners.
How can I collect rainwater in Seattle?
The city's own route is a RainWise cistern, a large above-ground tank that collects roof water and slowly releases it to the storm sewer, which helps cut combined sewer overflows. In eligible areas the rebate is up to $9.91 per square foot of roof captured. A rain garden handles the water in the ground instead, soaking it into spongy soil, and earns the higher rebate of up to $13.12.
Do I need a permit to build a patio cover in Seattle?
Usually, if it has a solid roof. SDCI exempts patios on grade and arbors or other open-framed landscape structures up to 120 square feet, outside environmentally critical areas. A solid cover is not open-framed, and covered areas count toward lot coverage in Neighborhood Residential zones. Describe the size, roof and attachment to SDCI before ordering a kit.
Check contractor credentials with Washington Labor & Industries. Match the business identity and scope to the proposal.
Sources
- RainWise, Rebates for Rain Gardens and Cisterns
- RainWise, Eligibility
- RainWise, Rebate Process
- SDCI, Do You Need a Permit?
- SDCI, Stormwater Code
- SDCI, Trees & Codes
- SDCI Tip 242B, Tree Removal on Private Property
- SDCI, Decks
- SDCI, Garages
- SDCI, Neighborhood Residential zoning summary
- Public Health, Seattle & King County, Hire a registered contractor
- SDCI, Electrical Permit
- Seattle SDCI building permits, open data
- U.S. Census Bureau, American Housing Survey 2023, Table 16
- U.S. Bureau of Labor Statistics, May 2025 wages, Seattle-Tacoma-Bellevue
Keep planning.
Explore the general outdoor living guide for project-wide ideas.
- Kitchen remodeling in Seattle →
- Bathroom remodeling in Seattle →
- ADU & garage conversion in Seattle →
- Roof replacement in Seattle →
- Basement remodeling in Seattle →
- Decks & pergolas in Seattle →
- Flooring installation in Seattle →
Outdoor living in other regions
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Planning guidance, not a quote. Confirm current requirements for your address with the official sources linked above.
