Seattle Rockeries is a retaining wall contractor who specializes in designing and building retaining walls using stone, boulders, rock and concrete. Retaining walls are used to create level areas within sloped landscapes to retain soil and create usable space for garden and landscape designs. We use quality materials and staff expert retaining wall engineers and retaining wall construction experts to form long lasting retaining walls in your outdoor landscapes.
Retaining walls are used to stabilize soil and help prevent erosion. Retaining Walls create terraces and strengthen your landscape during bad weather and rainy seasons. Retaining walls are installed with drainage systems to prevent soil over saturation and divert water from pooling in any one area of your landscape.
Manufactured concrete block retaining walls are becoming popular as a way to create large permanent retaining walls to hold large volumes of soil, on large slopes. Concrete retaining walls are engineered using blocks of many sizes, shapes and colors. Concrete blocks are stacked and interlocked atop of compacted, crushed gravel.
Upside: Timber is often used to create retaining walls since procuring timber is often easier and cheaper than ordering block or poured concrete used for constructing a concrete retaining wall. Also, the color and the overall texture of a wooden retaining wall is made from aged timber adds a more natural appeal to the yard or the garden space.
Downside: Timber retaining walls do not offer the resilience that is offered by concrete-enforced retaining walls. Pressure-treated timber has to periodically retreated, which is a time-consuming and tedious process. In terms of the wall height, timber-made retaining walls are limited since the wood-based walls have a restriction in terms of height to ensure greater safety.
Use 8-foot-long, 6x6-inch pressure-treated wood designated "For Ground Contact," and have all materials delivered. Follow all rules for landscape fabric, drainage and backfill. All timber walls require deadmen every 4 feet at midwall height or higher. Pin the first tier of timbers to the ground with #4 rebar.
Upside: Segmented retaining walls use interlocking-block systems from Keystone, Risi, Rockwood, Tensar, Versa-Lok, among other brands. These retaining walls are mortar-free and easy to assemble. Units are small and modular, so walls can taper, turn, wrap, and curve. Concrete Block retaining walls are available in many textures, shapes, and colors. These engineered systems, which can be used for walls up to 20 feet high, rely on several techniques including:
•Keyed and battered design (blocks fit into each other and are stacked so they lean into the hillside)
•Backfill trap (block shapes allow backfill to be shoveled into the block webbing, trapping each block individually)
•Geo-grid webs (geo-grid plastic-net tiebacks attach to the blocks and are buried 5 feet in the hillside at specific heights).
Downside: You can't mix and match manufacturer's systems. Most block systems that use metal pins to tie blocks together can be a challenge to line up exactly.
Arrange before delivery from the masonry yard where materials will be stockpiled in your yard and if the forklift used to off-load the truck will fit through backyard gate, etc. Follow all rules for landscape fabric, drainage, and backfill. Use manufacturer's calculators to determine how many blocks, pins and tiebacks you'll need. When stacking blocks, sweep off each layer; small pebbles can disrupt the pattern. Cap walls with flat units or stone held down with silicone caulk.
This happens when: A load is added within 3 feet of the top of the wall. The wall then leans out at the top and eventually tips over.
What to do: Plan your landscape with a Seattle Rockeries architect or engineer if a car or pool will be placed near the wall. Our retaining wall designs will include a strengthened footer and increased number of tiebacks or deadmen to add strength.
What happens: Soil behind the wall gets saturated with rain and storm water, causing hydrostatic water pressure and weight to topple the wall.
What to do: Seattle Rockeries builds our retaining walls with gravel drainage and waterways to route exess rain and storm water to protect from oversaturating the soil behind the retaining wall.