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Basement construction using Stepoc hollow blocks

When it comes to constructing basements, Stepoc hollow blocks are an excellent choice for retaining wall construction. In this blog article, we will discuss the general principles of basement wall construction using Stepoc blocks, as well as explore the two primary construction methods: foundation and raft construction. Additionally, we will delve into the importance of waterproofing in basement construction and discuss various options available.

Foundation basement construction:

For the construction of a retaining wall foundation, a reinforced foundation is crucial to ensure structural stability. The width of the Stepoc wall comes in three options: 200mm, 256mm, and 325mm. The structural engineer will determine the appropriate width and the steel required within the wall to withstand the load case for the wall.

Raft basement construction:

In cases where the soil-bearing capacity is poor, constructing a raft foundation can be a more cost-effective solution. A raft foundation spreads the building load over a larger area, mitigating potential stability issues.

Waterproofing:

Waterproofing is a critical consideration in basement construction to prevent water seepage and damage. There are several options available for waterproofing, including external waterproofing, internal waterproofing, or a combination of both.

Internal waterproofing is typically used to address moisture issues in existing basements that are damp, leaky, or prone to flooding. It is also suitable when construction limitations impede access to the outside face of the wall, such as sheet, contiguous, or secant piling projects.

External waterproofing, on the other hand, is often implemented during new construction to effectively prevent water from entering the structure. It can be achieved by priming the wall surface, applying a self-adhesive bitumastic membrane, and protecting it with a geodrain sheet. The geodrain further directs any water that comes in contact with the wall towards a perforated drain while safeguarding the waterproof membrane.

In both external and internal waterproofing systems, a perforated drain is installed at the base of the wall and covered with clean stone of up to 20mm. If backfilling the wall with soil is required, a geotextile membrane should be placed over the stone to prevent drain clogging caused by fine soil particles.

In terms of internal waterproofing, a geodrain membrane is applied to the outside skin of Stepoc blocks, accompanied by a cavity gutter at the bottom. Any water that enters the cavity is then efficiently drained away using a pump fitted to the gutter. Additionally, a damp-proof membrane is applied underneath the floor slab to prevent dampness from rising into the floor.

Reinforced concrete walls

The other most common type of retaining wall construction is the design and construction of a reinforced concrete wall. The design is similar to the Stepoc hollow blocks, but formwork is used to support the concrete while it cures rather than using the stepoc blocks. The cost is normally more expensive, and the process takes longer to build. Engineers tend to design reinforced concrete walls, but Stepoc is preferred by contractors.

In conclusion, Stepoc hollow blocks provide an optimal solution for basement construction, particularly when it comes to retaining wall solutions. Whether employing foundation or raft construction, and implementing external or internal waterproofing measures as necessary, Stepoc blocks offer durability, stability, and efficient functionality for a successful basement build.

Other types of basement walls construction

When the basement cannot be excavated safely to build the basement wall, other techniques may be required. These include:

• King post retaining wall 

King post retaining wall consists of steel universal column sections, spaced from 1.5m to 2.5m centres and the channels filled with concrete panels.

• Sheet piles

Sheet piles and shaped steel sheets that are driven into the ground. They work for small wall heights but require ground anchors over 3m

• Contiguous piles

Contiguous piles are constructed by drilling holes in the ground using a large auger. The holes are filled with reinforcement steel and concrete. The pipes are spaced, so they just touch each other.

• Secant piles

Secant piles are similar to contiguous piles, but they are closer together and cut into each other.

One of the above techniques is used to retain the sides of the excavation. They can be temporary structures or permanent structures.  A temporary structure allows for the excavation and the new basement wall to be constructed, then either left in and buried or removed. A permanent structure becomes part of the new basement wall.

King post retaining walls and sheet piles are typically temporary, whereas contiguous and secant piles are generally permanent. All the methods above are far more expensive than a simple excavation and a Stepoc hollow wall construction but must be considered for projects with poor soils and extensive and deep excavations.

All the above techniques are a cantilever design. The depth that the piles or posts penetrate into the ground will be deeper than the height of the wall. The actual depth will depend on the soil types and load case for the wall.

For more information or assistance with your retaining wall project, feel free to contact our team by heading over to the contact us page now or complete the form below:

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