How to Build a Basement in Your Landed Home
Ever wondered how a basement was built? Basements are like rooms that are built under the ground rather than above it. In some ways the basement is almost an extension of a building’s foundation. It’s difficult enough to build a basement along with the foundation; so how on earth are you supposed to build a basement under a house that is already there? The most common method for building a basement under a landed house is called underpinning which redistributes the weight of the foundation in order to hollow out a space for the basement without causing the foundation to collapse. There are several different forms of underpinning depending on the size of your house. It is highly recommended that you get professional advice before using any of these methods on your home!
Mass Concrete Underpinning
This method of underpinning involves digging out box-shaped holes, one-by-one, and filling each one with concrete. You must always wait for the concrete to solidify in each hole before digging out the next, or you will risk the integrity of your foundation. This method is one of the easiest because it can be done without the use of heavy machinery. You should use this method if you are planning to build a reasonably small basement.
Beam and Base Underpinning
This method is a bit more difficult. A reinforced concrete beam will be placed from the ceiling of your basement to the floor. The flooring of the basement will then be filled with concrete fused to the reinforced beam. This way the concrete ‘base’ of your basement will balance the foundation with the reinforced beam holding it all up. As soon as this is done, you should build concrete walls throughout your basement to seal off any potential cracks in the foundation. This method can be used if your basement is going to be slightly larger than average; however, if you wish to have a large basement, around the size of a lounge area, this method is not advisable. The reinforced concrete beam can only hold up so much weight. The wider your basement is, the more pressure is resting on that beam!
Expanding Resin Injection Underpinning
If you really need a large basement, then this is the method you want to use. Creating a basement through expanded resin injection involves using a machine to inject structural resins and hardener directly into the foundational area of your basement. You can literally build your base and walls with this resin injection without even needing to excavate first! Once you have injected a sufficient quantity of resin and hardener, you will be able to remove the remaining soil from your basement. As you dig you will eventually hit the hardened portion of your foundation; when you have successfully dug to each section of foundation you will already have your completed basement. This method is great for larger basements and is quite easy, provided you have the correct equipment; however, it is far more expensive than the other methods.