Mat foundation, also known as raft foundation, is the solution when shallow or combined foundations become expensive or can not carry the loads from the structure. There are many reasons why mat foundation is chosen by builders across the globe. One reason is if the soil, on which the building is constructed, does not have sufficient bearing capacity. Since, this soil is not able to support the building on its own, a mat foundation is built under the building. Another reason why builders prefer this kind of foundation is when a building has to be made on a mining area or it has a subsoil water condition. One more reason, why mat foundation finds place under a building is when the landscape is such that individual pillar cannot be constructed or the design results in overlapping of these support pillars.
In all of these situations, the mat foundation gives the required support needed for the building to stand strong.
The construction of Mat foundation
Mat foundation is constructed as a large slab which works as the base for the building. The building then rests on this foundation, leading to lesser contact with the land and hence more strength and stability. The Mat foundation is also reinforced with many bars inside it which run perpendicular to each other. Such reinforcements make it a very strong base, which is ideal for large buildings.
The mat foundation is always larger than the structure itself. The site where the structure has to be constructed is first excavated. When the site has been leveled and dried up, the slab of the mat foundation is laid down. This gives the building a foundation which is strong and durable and the construction starts on the slab.
Advantages of a mat foundation
There are many reasons why a mat foundation is one of the most used foundation in difficult areas. Here are some of the advantages:
- Mat foundation is one of the most dependable solution to uneven and difficult land areas. Sometimes the soil has a low or bearing capacity while other times, making individual footing is not feasible. A mat foundation is the solution to all of these problems.
- The other great advantage of the mat foundation is that it is economical as compared to other foundations. Consisting of the floor slab, the cost of making it are significantly lower than other more elaborate foundations.
- The excavation required for the mat foundation is way less than what is required by other foundation. This saves resources, labor as well as money.
- Mat foundation is perfect for soil that is subjected to subsidence. For e.g. clay is a kind of soil that keeps on contracting and expanding as the temperature changes, this is why, building a structure directly on the soil can make it dangerous. A mat foundation, on the other hand, will provide a stable base on which the building can be constructed. It remains unchangeable with varying degrees of temperature.
Disadvantages of Mat foundation
There are a few drawbacks of this kind of foundation, including:
- Sometimes, mat foundations need heavy reinforcement in certain areas, which can add up to the price of the manufacture.
- The edges of the mat foundation, if not properly take care of, may erode with time. However, when maintained well, these edges can last as long as the building it supports.
- Sometimes, the design can become very complex and thus, requires really skillful and experienced engineers as well as workers. This can be a problem when a builder doesn’t have access to skilled workers.
- Frost can have an adverse effect on the mat formation.
These drawbacks are small in front of the advantages that mat foundation provide in terms of cost of the project and feasibility. This is why, these foundations are used by the worldwide builders to construct buildings on a structure.
This is also the reason why more areas and soil conditions are opening up for construction and building. Earlier shifting soils or mining areas were considered dangerous for building structures. Today, with the advent of mat foundation, the scenario has completely changed. Mat foundation is providing a solid base for many buildings all across the globe.