Retaining walls are commonly used to level or retain slopes. They also provide inviting places to sit, while also increasing useable yard space. While retaining walls are made out of many types of building materials; boulder, wood, natural stone, or poured concrete, segmental retaining walls have gained popularity due to the availability of different colors, textures, patterns, and sizes, while still remaining functional. The type of retaining wall you choose will depend on factors such as; personal taste, soil type, function, and budget. The benefits of segmental retaining walls are:
- Design flexibility
- Size allows them to be used in difficult locations
- Easily create curves and unique layouts
- Provides owners with an attractive yet structurally sound system
- Variety of sizes, shapes, textures, and colors
- Ease of Installing
- Drying stacking technique allows erection of wall rapidly
- Manufactured of high compressive strength (4x the strength of conventional concrete)
- Low absorption
- Maintenance Free
- Property value
- Can add as much as 10% to the value of the property
Despite being a simple structure there is a lot of engineering that goes into creating an aesthetically pleasing wall that will serve its purpose indefinitely. To properly construct a retaining wall you must take into consideration the following factors along with having knowledge of:
- What object or material the wall is going to be retaining if any
- Determining the embedment of the wall that will be buried beneath the soil to provide stability
- Each embedment will vary based on wall height, unit size of block, manufacturers specifications, but a general rule of them is to bury the first course
- For every 8” of wall height you should bury the wall 1” into the soil.
- Knowing your final grade will determine your starting height based on block thickness and existing ground level.
- It is often necessary to use a laser to capture elevation differences especially over a long terrain. This will help to determine your starting point to capture the right grade height.
- Type of material used for the base, backfill, and drainage.
- The depth and width of the base depends on the block size and height of the wall. Standard 4”-6” compacted based that is 2x the width of the block
- 4”-5” compacted layer of crushed gravel ( dolomite) followed by a 1’’ layer of stone dust that compacts well but is easier to work with
- The backfill used behind a wall can vary greatly depending on the type of block used, batter (setback), and also the shear height of the wall.
- A good rule of thumb is any wall with zero setback and under 2 feet in height can be backfilled with clean compacted fill sand. It is also important to place landscape fabric behind the wall so that sand does not find its wall through the wall.
- Typically walls over 2 feet in height with zero setback will require special reinforcement and backfill. (Every wall is different and each manufacturer will have technical specifications based on the type of wall used). In such cases, reinforcement such as geo-grid is used to lock the wall in place to help retain the wall. How many times u need to use geo-grid and how deep will depend on the height of the wall and manufacturers specifications. When geo-grid is used backfill is usually comprised of compacted dolomite, along with pea-gravel.
- Depending on the block being used, walls over 2 feet in height generally required proper drainage to divert water away from the base of the wall.
- A perforated sock pipe is placed directly behind the wall the capture any water runoff in the soil and divert it away from the base.
- The drainage is comprised of pea gravel that is typically 12” deep behind the wall and extends all the way up the wall to within 4”-6” of final grade.
Too often walls are installed without considering all these factors and the life span is very short and the investment is lost. Whether you are looking to expand your usable space or retain a hillside Dawson’s Landscaping LLC will evaluate your property and offer their experience and expertise to help shape and accent your landscape with artfully constructed wall that will serve its purpose well into the future.
Dawson’s Landscaping LLC offers a variety of options when creating that perfect look including:
- Segmental block
Dawson’s Landscaping LLC works with only the industry’s most recognized manufacturers that offer extended selections with proven long-lasting strength and durability: