Do you need movement joints when building a retaining wall?

No, if you use segmental retaining walls, such as Tobermore’s Secura Grand, you do not need movement joints. The modular concrete blocks interlock with each other and do not require the use of mortar. This gives the modular segmental retaining wall the flexibility to cope with movement without the need to incorporate movement joints. 

Where retaining walls are of masonry construction, movement joints must be included. Failure to do so could lead to cracks in the retaining wall that weaken its structural integrity and could eventually lead to its failure.  

Movement within a retaining wall could be caused by several factors: 

• Variations in air temperature causing expansion and contraction of bricks or concrete blocks. 

• Expansion caused as clay bricks age. 

• Shrinkage that occurs as concrete bricks and blocks age. 

• The heat absorbed and the resulting expansion when the surface of the retaining wall is exposed to sunlight. 

• Expansion and contraction of surrounding soils. 

If you do not choose a segmental retaining wall for your project and therefore need to include movement joints, we will have a closer look at the best practice advice available. 

What are the key design considerations for movement joints in retaining walls? 

The key design considerations for movement joints can be found within the NHBC’s Technical Guidance 6.1/28 ‘Movement joints in masonry walls’.

The considerations include: 

• The provision of vertical movement joints every 6m to allow for drying and shrinkage. 

• Designing to ensure that a maximum length to height ratio for brickwork panels of 3:1 is not exceeded. To do so would make retaining walls more vulnerable to cracking. Where this is not possible, movement joints should be moved to closer centres than 6m. 

• Planning the positioning of movement joints in retaining walls prior to their construction so they can be concealed behind hard landscaping features where possible. 

• Ensuring that the mortar specified in a retaining wall is suitable for the construction as specified in table 15 of the PD 6697: 2019 document. 

As well as the recommendations contained within these documents, advice on constructing retaining walls should be sought from the manufacturer or a qualified structural engineer on the system you are considering. 

Whilst the correct design and construction of movement joints in retaining walls can increase their long-term performance, the choice of materials also plays a large part in the robustness and functionality of retaining wall solutions. 

In addition to movement joints what material choices can increase the robustness of retaining walls? 

Making the material choice to remove the need to have movement joints by constructing a segmental retaining wall with interlocking concrete blocks and no mortar is a great way to increase the robustness of retaining walls.  

Once the choice of retaining wall type is made, the physical properties of different retaining wall bricks or blocks should be compared. Variations in their performance characteristics can help increase the robustness of retaining walls.   

Whilst clay bricks may be considered for retaining walls due to their aesthetic properties, there are other options available that can look as good and bring increased strength and resilience to the final construction. 

Secura Grand concrete retaining blocks have a minimum compressive strength of 40N/mm2. Their exceptional structural stability is achieved via a three-way mechanism that can deliver geogrid reinforced walls up to 9m high. 

The hollow core of the blocks is filled with granular aggregate. The three-way locking mechanism is due to the interlock between the aggregate in the voids and the geogrid which resists movement. Additionally, friction is present between the ribbed geogrid and the texture of the concrete plus the retaining nib on the blocks. This effectively resists the forward movement of the blocks and acts as a clamp when under load, maintaining the connection with the geogrid. 

Alex Walther, Retaining Wall Category Manager at Tobermore, comments about the proven resilience of Secura Grand:

“The resilience of Secura Grand is highlighted by the fact that it has met the rigorous requirements of BBA HAPAS certification for use in highways and related areas. Secura Grand retaining walls and bridge abutments have the durability to meet the required HAPAS certification’s design life of 120 years, giving our customers added peace of mind.” 

Secura Grand segmental retaining walls are mortarless, fast to build, and remove the need to have skilled bricklayers or to include any movement joints, reducing build time and costs in the process. The retaining wall blocks come in vibrant long-lasting colours to help meet the aesthetic requirements of your project as well as boost the longevity of your chosen retaining wall solution.  

Where can I get advice on the construction of movement joints in retaining walls? 

Tobermore has extensive advice and guidance documents available to ensure that you construct your retaining walls in line with industry best practice standards and recommendations.  

Our Fastfind service can supply you with typical design drawings when you construct geogrid reinforced walls using Secura Grand.  

To learn more about retaining walls, you can book a CPD or contact our sales team who will be happy to guide you through the retaining wall choices available for your project.