Capital Piling Ltd Announces Sponsorship of Dorking Wanderers Football Club
We at Capital Piling Ltd are thrilled to announce our official sponsorship of Dorking Wanderers Football Club.
Although there are a dozen essential components of a construction project, perhaps the most important of all is the foundation. Foundations support your home and bear its weight; without a solid base underneath it, it’s really only a matter of time before your building experiences some serious structural damage. The foundation is also one of the areas of your home that crucially needs to be done right the first time, as if something goes wrong during the construction process, it’s not always easy to fix. To this end, it’s always worth your time to ensure that the foundation is completed to a high standard, but also that the type of foundation you choose is the most appropriate for the individual specifications of your construction project. To help you determine what foundation is best suited, this guide will cover one of the most popular types - the RC raft foundation - highlighting its benefits, comparing it to other commonly used foundations and detailing the installation process.
Reinforced concrete (RC) foundations, otherwise known as slab foundations or mat foundations, are a type of shallow foundation that is formed by reinforced concrete slabs of a uniform thickness (typically 150mm to 300mm). They are used to cover a wide area, and often act as the entire footprint of a building. This type of foundation spreads the load of the building over a larger area than other foundations do, minimising the pressure on the ground. They take their name from the fact that they ‘float’ on the ground, just as a raft floats on water.
Raft foundations are ideally suited to areas where:
As mentioned above, raft foundations are a type of shallow foundation which work perfectly for buildings where the overall load of the project will be low. However, as a general rule of thumb, the taller the building, the deeper the foundation should be. To this end, there are a number of deep foundations that are better suited to multi-storey buildings, the most popular of which is a pile foundation. Here, we’ll discuss the key differences between the two types of foundations to give you a better idea of which would be best for your project.
As a shallow foundation type, raft foundations consist of a ‘mat’ of concrete that sits either on top of, or just under, the ground. As they are ideally suited to one or two-storey buildings or spaces where a basement is required, they are frequently used during domestic construction. Raft foundations are a popular choice because they tend to be quick and inexpensive to build. Compared to other types of foundations, they don’t require deep excavations to be made, and they use fewer materials as the foundation is combined with the ground slab. However, you won’t find them being implemented in situations where heavy reinforcement might be required in certain areas as they tend to be less effective in this regard. They can also be prone to erosion at their edges over time.
By contrast, rather than sitting on top of the ground, pile foundations are driven deep into the ground to better support very heavy structures. They are particularly effective in areas where the ground is weak and the load of the building needs to be transferred to more supportive soil deeper underground. Piles are driven into the ground or cast in place, which means that soil is removed in order to install them. A pile cap will then link groups of piles and create a larger area for the distribution of the building load onto the piles.
There are several different types of pile foundations, including:
Pile foundations are an incredibly complex foundation type, and it’s essential that they are installed by an experienced piling specialist. While they do tend to be more costly as a result, they are very effective.
Raft foundations are generally constructed on a compacted hardcore base (approximately 100mm thick), after which a layer of binding concrete may be laid to allow the raft (approximately 50mm) to be formed, with a waterproof membrane above. They tend to incorporate steel reinforcement to prevent any cracking, as well as stiffening beams or thickened areas that provide extra support for specific loads - for example, below internal walls or columns. Beams may stand proud either above or below the raft, or ‘hidden’ beams might be used - formed by reinforced areas within the depths of the raft itself. These thickened areas are particularly useful when ground conditions are poor, as the needed thickness of the raft might be uneconomic otherwise. However, a site assessment is generally carried out to help the engineer understand what condition the ground is in. Very poor ground conditions may mean that a different solution is necessary, such as piling.
The raft design generally features an ‘edge beam’, formed by a cage of steel reinforcement, which will need to be carefully assembled on site. Internal stiffening beams are sometimes required too. These beams spread the building loads throughout the slab and then evenly over the ground. A concrete toe often supports the external leaf of the wall.
The raft design will typically need a hardcore sub-base to level out the ground. This stone should be mechanically compacted. It is also crucial that steel reinforcement is lapped at least 450mm (for mesh and mild steel bars) and combined with a 40mm concrete cover. ‘Treading in’ the reinforcement during the concrete pour isn’t an appropriate means of placing reinforcement. The edge of the raft must be meticulously detailed for the damp course and membrane position, which might need a ‘step’ forming in the concrete at the raft edge.
Insulation is usually placed over the top of the raft, with a concrete floor or raised floor above. In some circumstances, drainage and geotextile barriers might be required to prevent free-draining materials from getting clogged up by the surrounding soil.
Finally, it’s also important to note that a structural engineer may not have the full picture when it comes to damp coursing, cold bridging or land contamination issues. Ensure that they are fully aware of these details before construction begins, as once the concrete is poured it can be difficult to overcome.
If you’d like to know more about RC raft foundations, or other foundation types, Capital Piling can help. We are a specialist foundation and piling company which offers a comprehensive range of piling services for both domestic and commercial clients. Our professional teams are highly experienced in the installation of high-quality foundations on a wide variety of projects. We pride ourselves on our commitment to building strong relationships with our clients, and our complete transparency means that you can put your trust in us to deliver a stellar final product. From the outset, we will take the time to understand your needs and determine how we can best be of service to you. We’ll also visit your site to get a better understanding of what you’re working with, before assigning you a personal project manager who will be by your side all the way through to the project’s completion. Plus, with our competitive prices, we’ll always deliver value for money with our thorough service.
Whether you require foundations to expand your growing home, or you’re looking for a strong team to assist with a major commercial project, choose Capital Piling. We operate in London, Essex, Kent, Surrey, Berkshire and Bournemouth. For more information about our services, or to request a free, no-obligation quote or site visit, please get in touch by calling 0333 202 6412.
