When constructing a building in the London area, we sometimes run into problems where the ground is too soft to support it and doing extra excavation to provide a good foundation would take a massive amount of extra digging at a great cost to the project. There are alternatives, however, and a raft foundation can be built to serve the purpose. This particular foundation is suitable for a number of countries, including the UK and other countries where the climate varies and so it is becoming increasingly popular.
What Is It.
So, what is a raft foundation? Well, it’s constructed of strengthened concrete slab and it’s constructed for the whole building on the ground level. Its purpose is to support the overall load over the specified area and ensures that the building is not damaged or affected due to ground movement. The thickness of the slab differs depending on the job, but it generally varies between eight to twelve inches. Before putting down the slab, the soil must be prepared and a sand cushion needs to be made and for quite a lot of groundwork in London, this is essential.
There are also two types of this particular foundation. They are known as classic and floating. The classic type is constructed below the general level of the soil freezing and the floating type is put down at a depth of about twenty five to thirty five inches. This however doesn’t allow you to construct the ground floor or a basement for that matter. You can also have an ordinary foundation which is done by digging a pit which is then filled and levelled which should provide a cushion of at least six inches. There is also solid or insulated, which is very useful for colder countries and a whole lattice slab which is used for massive construction projects.
The raft foundation is thought of as the best option for homes as it can be used on most soil types from sandy to clay and it aligns perfectly whether the ground displaces vertically or horizontally. When constructing a building any type of construction material can be built on it. It is crucial that when laying the foundation that waterproofing the area and adding the correct drainage system is completed and if required, make reinforcements around the outside. When you begin to pour your concrete, put it in layers of six inches each and be sure that the vibrating is done to provide extra strength. If you intend to use ready-made rafts, then you just need to screed over the top.
The advantages to a raft foundation are that it is relatively easy to install and it provides a safe, strong and long lasting solution for your home. When looking for a suitable company to complete the work, look for one that has many years experience and have done this work before. Look at projects that they have done and if possible talk to the owners of the building and inquire about issues experienced if any. Don’t be afraid to ask questions so you understand what’s happening from start to finish.