Segmental vs. Boulder Retaining Walls in Western Washington
Retaining walls play an important role in landscaping across King and Snohomish Counties. From stabilizing slopes in Shoreline and Edmonds to creating terraced gardens in Bothell or Bellevue, they solve functional challenges while adding beauty to outdoor spaces. Two of the most common wall styles are segmental block retaining walls and natural stone or boulder walls. Each has its strengths, and the best choice depends on your property, goals, and budget.
Segmental retaining walls: modern and versatile
What they are
Segmental retaining walls are built with precision concrete blocks designed to interlock without mortar. These modular systems are engineered for strength and allow for detailed design flexibility.
Advantages
- Structural reliability – Engineered to handle soil pressure and weather in our wet Northwest climate.
- Design options – Available in a range of colors, shapes, and textures that can match nearly any home style.
- Efficient installation – Smaller blocks are easier to move, making them ideal for properties with limited access.
- Permitting ease – Because they’re pre-engineered, it’s simpler to demonstrate compliance with local building codes.
Considerations
- May not provide the organic, rustic feel of natural stone.
- If repairs are ever needed, lower sections of the wall can be more complex to access.
Best uses
Segmental retaining walls work well for backyard terraces, patios, garden beds, and tiered landscapes where precision and clean lines are a priority. They’re especially practical in neighborhoods with limited yard space.
Boulder retaining walls: natural and timeless
What they are
Boulder or natural stone retaining walls are constructed from large stones sourced locally or from quarries. They rely on weight and careful placement to hold soil in place, creating a natural, rugged appearance.
Advantages
- Natural aesthetics – Boulder walls blend into the Pacific Northwest landscape, aging gracefully over time.
- Durability – Stone withstands rain, wind, and freeze-thaw cycles with minimal wear.
- Eco-friendly – Using locally sourced boulders reduces transport impact and feels authentic to the region.
Considerations
- Require heavy equipment for placement, which adds cost and may limit use in tight spaces.
- Performance is less predictable without engineering specs, so additional planning may be needed for permits.
Best uses
Boulder walls are ideal for large properties, rural lots, or naturalized settings where blending into the landscape is more important than tight geometry. They’re especially effective for framing driveways, anchoring steep slopes, or building along wooded areas.
Factors to consider in Washington
When choosing between segmental and boulder retaining walls, think about:
- Property access – Segmental blocks can often be carried by hand, while boulders need machinery.
- Slope steepness – Segmental systems allow for precise terraces; boulders complement more gradual slopes.
- Permits and regulations – Many cities in King and Snohomish Counties require permits for walls over 4 feet. Segmental walls have clear engineering specs, which can simplify the process.
- Design goals – Do you want a modern, structured look or a natural, organic feel?
Retaining wall services in King and Snohomish Counties
At Greenleaf Landscaping & Construction, we design and build retaining walls that are tailored to the property and climate of Western Washington. Whether you want the clean lines of a segmental wall or the rustic appeal of natural stone, we’ll create a solution that stabilizes your yard and enhances its beauty.
We serve homeowners in Shoreline, Seattle, Bellevue, Kirkland, Bothell, Woodinville, Edmonds, Lynnwood, Mill Creek, and surrounding communities.
Schedule a consultation
A retaining wall should do more than hold back soil — it should add character and value to your landscape. If you’re ready to explore your options, contact Greenleaf Landscaping & Construction today to schedule a consultation. Our team will walk you through the design, permitting, and installation process so your wall is built to last in the Seattle area climate.
