South King County
Paver Patios in Des Moines, WA
Quick answer
On a Des Moines bluff lot, where the patio runoff goes matters more than where the patio goes. Adding impervious surface above a slope that already sheds groundwater at the Lawton Clay contact is how movement starts, so the field gets collected and tightlined inland. We are fifteen minutes west of the Kent shop.
West of Marine View Drive the stratigraphy governs everything. It is the classic Vashon sequence: a dense till cap over advance outwash sand sitting on Lawton Clay. Rain moves down through the sand, meets clay it cannot pass, and comes out sideways at that contact. The elevation where groundwater daylights is the elevation where the bluff face moves, and you can read the record in the leaning alders below Woodmont and Redondo. A patio is impervious surface, and impervious surface concentrates water. On the west side of a lot here the drainage plan is the project. The field gets pitched inland, collected into a catch basin, and carried in solid pipe to a legal discharge point away from the slope, never allowed to sheet toward the crest.
That also means paperwork before shovels. Landslide, erosion and steep-slope hazards are mapped along the shoreline and into the Des Moines Creek and Woodmont ravines, and grading or excavation inside those areas or their buffers typically wants a report from a licensed geotechnical engineer. Property within 200 feet of the ordinary high water mark falls under the city Shoreline Master Program, where a patio can require a shoreline exemption and a longer review.
The design brief inverts what we hear inland. People bought for the water, Maury Island and the Olympics behind it, so the instruction is to keep everything low. Seat walls at eighteen inches rather than screens, planting that tops out below the sightline from the deck, and evergreen structure that still reads in February. Salt narrows the list further. Kinnikinnick, salal, evergreen huckleberry, hebe and carex hold up on a windward bluff-top corner where a hydrangea burns brown. Access is the last variable. Original 25 and 50 foot platted lots, narrow streets and short driveways mean we phase deliveries and stage on the property rather than parking a flatbed at the curb for a week.
What’s different about Des Moines
Des Moines is the one place we work where a patio can be a slope-stability question. Concentrating new roof and surface water above a marine bluff that already sheds groundwater at the till and clay contact is the mechanism that moves it, so the outfall is designed before the paver is chosen.
Paver Patios cost in Des Moines
| Item | Typical range | Unit |
|---|---|---|
| Standard concrete paver patio, running bond or herringbone | $22-$30 | per sq ft |
| Premium or large-format paver patioTecho-Bloc and Belgard slab lines, tighter tolerances and more cutting. | $30-$45 | per sq ft |
| Dry-set natural flagstone patio | $38-$60 | per sq ft |
| Over-excavation and structural fill on a soft subgradeDigging, haul-off, and imported rock combined. | $60-$95 | per cubic yard |
| Paver seat wall integrated into the patio edge | $65-$110 | per linear ft |
| Channel drain with piped outfall to daylight | $45-$85 | per linear ft |
These are typical installed ranges for the Puget Sound market and include labor, base, and materials; the number that ends up on your proposal comes from a site walkthrough where we can see access, grade, and what the subgrade is actually made of.
Permits in Des Moines
Permits go through City of Des Moines Planning, Building and Public Works. The standard Western Washington threshold applies: a retaining wall over 4 feet measured from the bottom of the footing to the top of the wall needs a building permit and stamped structural engineering, and a surcharge from a driveway, a structure above or a stacked tier can pull a shorter wall into review. Des Moines adds two layers that matter more here than almost anywhere else we work. First, geologically hazardous areas. Landslide, erosion and steep-slope hazards are mapped along the marine bluff and the ravines, and grading, walls or significant excavation inside those areas or their buffers typically require a report from a licensed geotechnical engineer on top of the structural work. Second, the Shoreline Management Act. Property within 200 feet of the ordinary high water mark of Puget Sound falls under the city Shoreline Master Program, where a patio, wall or grading project can require a shoreline exemption or a substantial development permit and the review timeline stretches accordingly. Added hard surface can also trigger stormwater review. These thresholds get revised, so we confirm with the city at permit time before committing to a scope.
Paver Patios in Des Moines: questions
Can I build a paver patio on a bluff lot in Des Moines?
Often yes, with the drainage and the geotechnical question answered first. What we will not do is add several hundred square feet of impervious surface uphill of a marine bluff and let it discharge toward the crest. The build we do recommend pitches the field away from the slope, collects it, and carries it in solid pipe to an approved outfall. Inside the mapped landslide and erosion hazard areas the city generally wants a licensed geotechnical engineer involved, and that report shapes the layout rather than rubber-stamping it.
Does the Shoreline Master Program apply to a back yard patio?
It can. Property within 200 feet of the ordinary high water mark of Puget Sound falls inside the city shoreline jurisdiction, and a patio, wall or grading project in that band may need a shoreline exemption or a substantial development permit. That is a timeline issue more than a cost issue, but it is a real one, and it is the single most common surprise for people buying near Redondo or the Marina District. We check the parcel against the shoreline mapping with City of Des Moines Planning, Building and Public Works before committing to a schedule.
My street is narrow and the driveway is short. How do you stage the work?
We plan it on day one instead of hoping. On the old platted streets we phase deliveries so a pallet load is not sitting where a neighbor parks, stage material on the property where there is room for it, and size the machine to the driveway rather than to the job. Some Des Moines back yards genuinely are wheelbarrow access, and when that is the case we say so during the walkthrough and price the labor honestly instead of discovering it in week one.
What does a paver patio cost in Des Moines?
Typical installed ranges for the Puget Sound market in 2026 are roughly $22 to $30 per square foot for a standard concrete paver field and $30 to $45 for large-format or premium units. Those are planning ranges rather than a quote. Des Moines adds two cost drivers other cities do not: restricted access on the older narrow-lot streets, which shifts work from machine to hand, and the piped drainage a bluff-side lot needs, commonly $45 to $85 per linear foot for a channel drain with a piped outfall. Geotechnical review, where required, is a separate consultant cost.