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The Anatomy of a Concrete Foundation
While it is true to say that a building’s foundation is not always visible once the concrete structure has been fully erected, it is still considered to be one of the most important elements of any construction project. By getting the foundation right from the start, structural issues that could arise in the future can be easily avoided.
So, what is a concrete foundation? The foundation refers to the part of the building that forms the basis of the structure. It helps evenly distribute the structure’s weight while ensuring that it is on a firm footing.
Concrete foundations are mainly either shallow or deep. Shallow foundations are designed for small-scale projects, such as houses and smaller buildings. Meanwhile, deep foundations are suitable for taller commercial and residential buildings. They are also strongly recommended for structures built on fragile ground as they can help transfer the building’s load to the stronger and more stable soil or rock below.
Shallow and deep foundations can be further divided into the following sub-types.
An individual or isolated footing mainly supports a single column. Also referred to as “spread footing” or “pad foundation”, it can be square, circular or rectangular in shape. It has frost depth, insulations, and crane ganging. This type of foundation generally has the same thickness and is built to carry and distribute concentrated loads.
Combined footing foundations support multiple columns. They are usually rectangular in shape.
A strip foundation supports load-bearing walls or a row of closely spaced columns. Its base distributes the weight of the structure over a wider area for improved stability.
Slab on grade
A mat or raft foundation is a large concrete slab designed to support and stabilise multiple columns and walls. It is spread across the entire structure and is generally used when a building is being built on soil with low pressure. It can also support walls and columns that are placed so closely together that individual footings would not be a suitable or cost-effective option.
Pile foundations are ideal for structures built on surfaces unsuitable for heavy loads. Using a special type of equipment, piles are driven into the ground and filled with concrete. Then, a ground beam is installed on the surface where the structure will be built.
Building Concrete Foundations
As mentioned earlier, the structural integrity of your project will mainly depend on the foundation it is built upon. Therefore, it is crucial that you get the foundation right as this will help prevent major problems in the future. If you are unsure as to which type of foundation and/or climbing scaffolding to use, we would recommend that you seek expert advice to avoid making costly mistakes. Moreover, to reduce your project time, labour and overall costs, it is imperative that you source the most appropriate foundation formwork systems, such as the ones we offer here at MEVA.
Once you have made a final decision, it is time to lay your building’s foundation. Here is a step-by-step guide to help you on your way.
Ensure that the construction site is ready
Once you have secured all the necessary permissions, the next thing you need to do is prepare the ground on which you will construct the building. No matter how big or small your project, it is crucial that you always prepare the site carefully to avoid simple mistakes that could lead to serious consequences.
Mark the area
Start by marking the location where the concrete is going to be poured. You can use wooden pegs and string for this task. When marking the area, make sure you leave enough space for the formwork which will hold the concrete in place until it solidifies in its final shape.
Dig your foundations
The next step is to dig the required depth for your foundation. Here, you need to consider the type of foundation you are going to lay. Strip footings are generally built on undisturbed and solid ground. Meanwhile, individual footing and floor slabs require enough depth to accommodate the sub-base, damp-proof membrane (DPM) and the concrete itself.
- Add the sub-base
After making the necessary excavations, the next step is to add the sub-base. For most domestic concrete foundations, 100mm of base aggregates should suffice. Then, lay a DPM, a membrane material (e.g. polyethylene sheeting) used in construction to protect concrete from moisture transmission. Make sure the edges are turned up so they form a tray. Also, check the joints to see that they overlap and are taped to protect the concrete from rising damp or chemicals in the ground.
- Install the formwork
Bear in mind that foundation formwork plays a vital role in the construction of your concrete foundation. Therefore, ensure that it is installed correctly.
Prepare the concrete
Once the site is ready, you can begin your preparations for pouring the concrete. However, similar to the type of foundation you want to lay, it is vital that you are careful when choosing the type of concrete you intend to pour. For instance, soil that contains sulphates can cause concrete to expand and weaken over time. An excellent way of remedying this issue is to use concrete with design chemical classes to ensure long-term stability and durability.
Pour the concrete
Always keep in mind that concrete usually starts to harden within two hours of being mixed and poured. The type of concrete used and the temperature on the worksite can also affect how fast it will set. For example, if you are pouring concrete in cold weather, it can take twice as long for it to harden. By contrast, concrete can set 30 minutes faster when poured in hot weather.
Prepare the necessary tools
Because you only have a short amount of time before the concrete begins to set, you should unload and level it as quickly as you can. Preparing the required tools beforehand will certainly be useful in this regard.
Leave enough room for the delivery truck
You must ensure that there will be enough space on the worksite for the delivery truck to manoeuvre freely. Otherwise, it could impede the pouring of the concrete, which could lead to project delays. Typically, trucks that deliver concrete are 9.5m long, 3m wide and 4m high. Meanwhile, trucks carrying ready-mixed concrete are often equipped with extension ramps that can be 3–4m high. Unless the concrete can be unloaded at any position on-site, you should consider using a concrete pump to expedite the pouring.
Pay attention to the weather
Before pouring the concrete, pay attention to the weather forecast as laying concrete in adverse conditions can have a negative effect on the finished product. However, if this is unavoidable, bear in mind the following advice to ensure you achieve excellent results:
- When pouring concrete, ensure that the air temperature is at least 3°C to prevent ice from forming within the mix. Otherwise, it could weaken the concrete.
- Never lay concrete on top of ice or frost. If the temperature begins to fall, you can use insulating blankets to protect the sub-base. Alternatively, you can heat the concrete.
- If it is raining, you must ensure that the ground drains well. Once the concrete has been poured, you should cover it with a tarp or plastic sheeting while it dries to prevent heavy rain from damaging its surface.
Level the concrete
After it has been poured, the concrete will be reasonably wet so you can use a rake or shovel to roughly level it. Then, make sure to remove any air pockets with a vibrator.
For best results, it is advisable to use high-quality concrete foundation forms, such as the ones we offer at MEVA. With our formwork systems, you will be able to save on time and labour costs while ensuring that the concrete will have a smooth finish.
Let the concrete set
To prevent its surface from being weak or dusty when the concrete hardens, cover the concrete slab with plastic sheeting to keep it damp. You should try to ensure that the edges are appropriately sealed to prevent wind or frost from penetrating the sheeting. In addition, make sure to leave the foundation formwork on for 72 hours before laying bricks or blocks. This will prevent any potential damage to the edges of the foundation.
MEVA’s Dependable Solutions for All Your Foundation Formwork Needs
With MEVA’s products, there is no need to plan how to build a concrete form from scratch. We offer an extensive range of reliable and superior-quality shoring tower and formwork systems to help you lay concrete foundations with maximum convenience and ease. With our formwork solutions, you can significantly reduce your overall project duration and costs while ensuring the safety and efficiency of your team on the ground.
Wall Formwork Systems
Our industry-leading wall formwork systems are not just designed for building concrete walls and columns. They can also be quite useful when forming foundation walls for a wide range of concrete structures. You can choose between steel or aluminium formwork, and no matter what your preference, you can expect outstanding performance and exceptional results.
Explore their unique features and specifications by visiting our wall formwork page.
Trust Only the Industry’s Formwork Experts
Building solid and robust foundations is crucial to the success of any construction project. This is why it is vital that you get them right the first time as this will help you avoid potential structural problems in the future. At MEVA, our goal is to provide our clients with premium formwork systems to make building strong and structurally sound concrete foundations a safer, faster and more cost-effective experience. We can offer you the solutions you need so you can reduce your costs and ensure the success of your project.
If you need any advice on this topic, our team of construction experts and formwork specialists are always on hand to answer your questions. Please use the contact details below or complete the form on this page to send us a message.