Retaining Wall Prices & Selection Guide
We provide blocks to build several types of retaining walls. This guide helps to select the most cost-effective retaining wall type for their project using BlockWalls.
Each project has its own unique set of conditions and constraints. The type of construction will depend on the location, site conditions, design constraints, ground bearing capacity and the material being retained.
In this guide, a number of retaining wall types and their construction costs have been analysed. Each design utilises distinct construction methods and materials.
The common factor in all the wall constructions is they all use interlocking concrete blocks. This allows for fast construction leading to increased efficiency and reduced preliminary site costs.
In this guide, BlockWallshas analysed the design criteria and construction costs to build a retaining wall 100m long and 3m high with a total area 300m2.
The following four types of builds were considered:
- Gravity Retaining Wall
- Reinforced Block Retaining Wall
- Inclined Block Retaining Wall
- Reinforced Earth Retaining Wall
Design Criteria
All designs are “indicative” based upon a base material with allowable bearing pressure greater than 200 kPa.
The retained material is assumed to be well graded, granular backfill with back of wall drainage or weep holes to relieve hydrostatic pressure.
All costs are based on average civil engineering costs in UK with a base date of 2016.
Gravity Block Retaining Wall
The gravity wall that has been designed is constructed using 1800 x 600 x 600mm concrete interlocking blocks in the configuration as shown in the sketch in Figure 1.
The dimensions of the base are 2600 x 100mm built with a C25 grade concrete with no reinforcement.
The design surcharge load is 2.5 kN/m2.
The cost analysis of this wall are in tables below. The earth works assume that a square section of earth 3 x 3m is to be taken away and replaced behind the wall on completion.
Reinforced Block Retaining Wall
The reinforced block wall has been designed to be constructed using 1800 x 600 x 600mm concrete interlocking blocks as configured in the sketch in Figure 2. This construction forms a cantilever retaining wall using a reinforced concrete base.
Patent Pending- We have filed for a patent and registered a design for this product.
The base has dimensions of 2200 x 300mm with rebars of grades A393 in toe and B785 in heel. The vertical rebar that has been used is H25.
The design surcharge load is 10 kN/m2.
The cost analysis of this wall is in the tables shown below. The earth works assume that a section of earth 3 x 3m is to be taken away and replaced behind the wall on completion.
Inclined Block Retaining Wall
The inclined block wall has been designed to be constructed using 1600 x 800 x 800mm concrete interlocking blocks as configured in the sketch in Figure 3.
The base is 2000 x 100-300mm with a single layer of A393 steel mesh as reinforcement. The surcharge load is 5 kN/m2.
The cost analysis of this wall is shown in tables below.
The earth works assume that a section of earth 1 x 3m is to be taken away and replaced behind the wall on completion.
Reinforced Earth Retaining Wall
The reinforced earth wall that had been designed is constructed using 1800 x 300 x 600mm concrete interlocking blocks as configured in the sketch in Figure 4.
It is built by back filling the earth in layers with a “Geomat” between each layer. The thickness of the layers depends on the soil type and design.
The base dimensions are 900 x 200mm and is reinforced with one line of A393 rebar. The surcharge load is 5kn/m2. The “Geomat” for this cost exercise is E Grid reference – 95R.
The cost analysis of this wall is in tables below. The earthworks assume that a section of earth 4 x 3m is to be taken away and replaced behind the wall upon completion.
The cost of this construction depends on the material on site. The reinforced earth wall requires a geo-technical design. The costs below are only an indicative guide.
Conclusion
The tables below show the ranking of each retaining wall type in terms of approximate cost. The reinforced earth wall is the most competitive to build.
The reinforced block wall is a more reliable option. It is a strong build and the wall can be constructed within a limited timescale on-site. It is ideal for fast track projects.
The gravity and inclined walls are simple and quick to construct. They require more blocks as they rely on the mass of the wall to hold back the retained material.
The rates per square metre can be used for an approximate guide to produce project budgets. They are only suggestive as each project will have different challenges.
Detailed Cost Analysis
Blockwalls has more tables with a cost index for various heights of walls from 1.2m to 6.4m using all four retaining wall types described in this guide.
Click on the image below to download a full retaining wall design and build guide including costs for all variants.
