Basement UnderpinningThis is the more expensive of the two options but it is also the one that will leave you with the most space once the work has been completed. Because there will be no bench walls inside your basement once the underpinning has been completed, you will be able to utilise every inch of floor space. In order to underpin a basement, or lower it, in this manner, the building contractor you hire will need to excavate beneath your existing foundations and pour new footings, in small stages. The reason that the work has to be completed in small stages is because your home is being supported by the foundations so great care needs to be taken at all times.
BenchingThis option involves excavating just inside the existing foundations and pouring new ones next to the existing ones, rather than underneath them. Because it does not involve removing earth from under the foundations on which your home is standing, a benching project can normally be completed more quickly than basement underpinning. The fact that it can be completed more quickly and that it involves less work and less risk of compromising the structural integrity of your home means that it is also the cheaper option as well. The size of the bench wall will depend on the height you are trying to gain. If, for example, you would like the ceiling in your basement to be 12 inches higher, you would need a bench wall that was 12 inches wide.
The Pros and Cons Associated with Each OptionTo make it easier for you to choose the most appropriate option for your particular needs, below is a summary of the pros and cons associated with each one.
- Basement Underpinning – More expensive but maximises the amount of extra space you can create by converting your basement. Furthermore, if you have any doubts about the quality of your existing foundations, having them underpinned will give you peace of mind.
- Benching – It costs less money, can be just as effective and completed more quickly than underpinning. However, on the downside, it will reduce the amount of space you gain from your basement conversion and will not give you the same gains in structural integrity that basement underpinning