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Sta-Built Construction leveled a sloping, moss-covered side lawn on Lake Washington Boulevard in Seattle, WA with a 78-foot curved Belgard block wall in Rio, 56 cubic yards of fill, and 725 square feet of synthetic turf, finishing in July 2026. The wall follows the inside of a tall laurel hedge and holds the raised, level lawn that replaced the old grade.
Project Details
- Location: Seattle, WA (Lake Washington Boulevard)
- Service: Retaining wall installation with synthetic turf
- Wall size: 78 linear feet, 178 sq ft of wall face, height stepping up to about 3 ft with the grade
- Turf area: Approx. 725 sq ft
- Retaining block: Belgard Diamond Pro PS smooth face in Rio, with matching corner units
- Freestanding block and caps: Belgard Melville Wall 4 x 10 x 20 and Melville caps in Rio
- Drainage and base: Perforated drain pipe with sock, 5/8 inch minus compacted gravel, drain rock behind the wall
- Earthwork: 9 cubic yards excavated, 56 cubic yards of fill brought in
- Turf: Sta-Built RealFeel synthetic turf over a 5/8 inch crushed rock base and geotextile fabric, seamed, spiked, and infilled
- Supplier: SiteOne
- Completed: July 2026
- Project investment range: $43,800 to $68,900
- Warranty: 17-Year Craftsmanship Warranty
Before and after
The problem
The house sits above the boulevard, and the side lawn ran downhill from the covered patio to a tall laurel hedge at the property line. Photos from the March 2026 site visit show a lawn that was mostly moss and bare patches, with the low edge disappearing under the hedge. A sloped, shaded, wet lawn like this does not hold grass well, and the pitch made the space hard to use.
The solution
Rather than fight the slope, Sta-Built raised the low side to meet the high side. A curved block wall was set just inside the hedge along 78 feet of the yard, the space behind it was filled with 56 cubic yards of soil, and the new level surface was finished in synthetic turf. The design sheet splits the wall into two conditions: a retaining section where the wall holds back the new fill, built from Belgard Diamond Pro PS, and a freestanding section where both faces show, built from Belgard Melville Wall block. Both are in the same Rio color and share the Melville cap, so the wall reads as one piece.
Turf made sense because the original problem was a lawn that could not grow here. The area is shaded by the house on one side and a tall hedge on the other, and it had already gone to moss once. Synthetic turf gives the homeowners a green, level yard without depending on sun the site does not get.
The materials
All the hardscape came from SiteOne. The retaining portion is Belgard Diamond Pro PS smooth-face block in Rio, a gray blend, with matching corner units. The freestanding portion is Belgard Melville Wall 4 x 10 x 20 block in Rio, capped along the full run with Melville 2 x 13 x 20 caps in the same color. Behind the wall the order included perforated ADS drain pipe with a filter sock, geotextile fabric, and Portland cement.
The turf is Sta-Built’s RealFeel synthetic turf, delivered in five rolls cut to the shape of the yard, with seam tape, turf adhesive, 6-inch turf nails, and 25 bags of Premier Green infill.
How it was built
The crew arrived the last week of June 2026. The first delivery from SiteOne was missing the base course of block, and the supplier was out of stock, so the wall base went in as soon as the block arrived. Photos from July 8 show the first course set along the hedge line in a compacted trench of 5/8 inch minus gravel, with the work order calling for a 4 to 6 inch excavation and roughly 4 inches of compacted gravel under the block.
The perforated pipe was laid behind the base course to carry water out from behind the wall, and drain rock was placed behind the block as the courses rose, with the work order specifying drain rock to within 8 inches of the top. Concrete adhesive bonds the courses and the caps.
Then came the fill. Fifty-six cubic yards of soil were brought in and spread behind the wall to bring the whole yard up to one level. On top of that, the crew built the turf base: 3.5 to 4 inches of 5/8 inch crushed rock, compacted and graded smooth, with geotextile fabric laid over the finished base. The RealFeel turf went down on July 13, seamed with tape and adhesive, fastened with 6-inch nails around the perimeter, and finished with infill. Final photos were taken July 14.
The finished result
The slope is gone. The side yard is now a flat, green lawn that runs from the covered patio to a clean capped wall along the hedge, and the wall’s curve follows the hedge line instead of cutting across the yard in straight segments. The mossy grade that used to slide under the laurel is now several feet of level turf.
What a project like this costs
Project investment range: $43,800 to $68,900. This range reflects the scope of this completed project and is not a current quote.
Two things drive this price. The first is earthwork: 56 cubic yards of imported fill is far more than a typical wall job, because the goal was to raise an entire yard, not just hold a bank. The second is the combination of two systems on one site, a 78-foot block wall with drainage and 725 square feet of turf on its own compacted base. The work order also carried an access fee for this site.
See more on our retaining wall page and our artificial turf page. We build walls and install turf across the city from our Seattle service area. Related Seattle project: a herringbone paver courtyard with a fountain.
Related questions
How much does a retaining wall with artificial turf cost in Seattle, WA?
This 78-foot Belgard block wall with 56 cubic yards of fill and 725 square feet of synthetic turf came in between $43,800 and $68,900. A wall that only holds an existing bank, without raising a whole yard, would cost considerably less; adding turf, more fill, or harder access moves it up.
What block was used for this wall?
Belgard Diamond Pro PS smooth-face block in Rio for the retaining section, Belgard Melville Wall 4 x 10 x 20 block in Rio for the freestanding section, and Melville caps in Rio along the full 78 feet, all from SiteOne. Perforated drain pipe with a sock and drain rock sit behind the wall.
Why build a wall instead of just installing turf on the slope?
Turf laid on the old grade would still have been a sloped yard. The wall let Sta-Built bring in 56 cubic yards of fill and create a flat lawn, which is what makes the space usable. The wall also gives the turf base a firm, contained edge along the hedge.
What is under the artificial turf?
About 3.5 to 4 inches of 5/8 inch crushed rock, compacted and graded smooth, with geotextile fabric between the base and the turf. The RealFeel turf is seamed with tape and adhesive, fastened with 6-inch turf nails, and topped with infill.
Does Sta-Built build retaining walls in Seattle?
Yes. This project is on Lake Washington Boulevard in Seattle, and Sta-Built builds segmental retaining walls, seat walls, and garden walls throughout the city from the Lynnwood showroom. Washington license: STABUL*782LN.
Planning something similar?
If a sloped, shaded lawn has gone to moss and you want level ground you can actually use, Sta-Built can walk the yard and recommend the right wall and surface. Schedule a free design consultation.
This project documentation was prepared by Sta-Built Construction from the project records and photos from our crew, September 2026. Technical review by Ben Metsker, Manager.