As a rule of thumb, it's generally recommended that retaining walls be positioned at least 3 meters (approximately 10 feet) away from a house. This spacing ensures adequate protection for your home's foundation, allows for proper drainage, and provides necessary maintenance access.
Maintain a Safe Distance from Structures
Keeping your retaining wall safe from your house and other structures is vital. A minimum distance of 3 meters from your house is recommended to protect your foundation. Apply similar spacing to garages, sheds, and other buildings to ensure safety and stability.
The basic principle for the design of the Retaining Wall is that the reinforced concrete stem and footing flexure and shear design strength must e at least equal to the factored moment and shears determined from the analysis. The wall stem is designed as a cantilever, fixed at the footing.
Absolutely! Even a 2-foot retaining wall needs an effective drainage system. Without it, water can build up behind the wall, leading to pressure that might cause the wall to lean or even collapse. All walls need systems to manage water effectively, preventing damage over time.
Hydrostatic Pressure and Wall Failure
When water isn't properly drained, it can accumulate behind the wall, exerting pressure on the structure. This pressure can prompt the wall to shift, crack, or even collapse. To avert such failures, it's crucial to have adequate drainage behind the retaining wall.
Base thickness = 1/8 of the height of the wall but not less than 12 inches. Stem thickness = 6 inches + ¼ inch for each foot of wall height.
The footing, or first row of your retaining wall, should be about 4 to 6 inches deep and about 12 inches wide, or twice the width of the block you are using. The blocks should sit about halfway into the soil.
A retaining wall can fail without tiebacks and anchors, leading to soil erosion, property damage, and even safety hazards. Tiebacks and anchors are particularly crucial for retaining walls that support large loads or are situated on slopes where the pressure from the soil is most intense.
Foundation Stability
Building a retaining wall too close to your house can put excessive pressure on the foundation, leading to cracks or even more severe damage. Maintaining at least a 3-meter distance allows the soil to support both structures properly without causing undue stress.
A retaining wall without a footing may experience settlement, leaning, or failure over time. Footings help distribute the weight of the wall and its load, preventing excessive pressure on the soil and ensuring long-term stability.
Soil saturation is the most common external factor that causes retaining wall failure, but there are many ways to prevent it.
Do you need drainage behind a retaining wall? Yes, which means you need backfill too. This backfill is the soil that's located in the first 12 inches of space right behind the retaining wall in order to have proper drainage, and it can be either gravel or crushed stone.
A Building Permit and engineering calculations are REQUIRED when: The wall is greater than 4'-0” measured from bottom of footing to top of wall.
Retaining walls are typically built between 3 to 4 feet tall. The typical height for most retaining walls is 3 to 4 feet.
The amount your retaining wall leans into the hill is called: Setback. Allan Block retaining wall blocks come in a variety of setbacks. Note: retaining walls designed with a 12° setback need more space than a 6° retaining wall but will be stronger and more stable.
Don't Forget To Backfill Behind Your Retaining Wall
Neglecting to backfill properly can lead to reduced support, increased pressure on the wall, and the possible collapse of the wall.
Deadman anchors are a retaining wall tieback system that consists of a poured concrete block 10' to 15' landward of the wall and tie rods that connect the block to the wall. Many existing seawalls in Florida are constructed with deadman anchors in place to keep the wall in a vertical position.
Anchored retaining walls (aka tie-back systems) have thin walls supported by anchors and cables. They typically cost $10 – $30 per square foot and can be made of any material. They also use gravity, but this method can be used to build taller walls than traditional gravity retaining walls.
Proper drainage is critical to prevent water buildup behind the wall, which can lead to pressure and eventually cause the wall to fail. For effective drainage, the choice of gravel is paramount. Fractured rock is often the preferred choice for the drainage layer of retaining walls.
What is the cheapest type of retaining wall? Poured concrete is the cheapest type of retaining wall, in terms of materials. Pressure-treated pine is next, and wood retaining walls are becoming more popular now. If you prefer stone, granite is generally the least expensive option.
The average cost to build a retaining wall is $20 to $50 per square foot or $40 to $300 per linear foot. Installing a 50' long retaining wall costs $4,000 to $10,000 on average. Retaining wall labor costs $10 to $30 per square foot, and material prices are $5 to $20 per square foot on average.
As a rule of thumb, the counterfort length at the bottom should be about 0.4 H = 10-ft long, therefore let's specify the heel length = 12-ft. The toe length will be determined by the pile loads. The At-a-Glance tab shows a summary of the design for a quick overview of your work as you go.