Mass Effect: Should You Choose Mass Concrete Underpinning To Strengthen Your Home's Foundations?

Posted on: 14 August 2018

The foundations of an average home are colossal and tremendously durable concrete structures—after all, they need to be to support the weight of an entire house for many decades. However, even the most redoubtable house foundations are still vulnerable to damage caused by subsidence, expansive soils and other forces, and it's very likely that, at some point during its working life, a foundation will need to be reinforced.

Reinforcing a home's foundations involves a process known as house underpinning, which essentially involves expanding the existing foundations to counteract the loss of load-bearing strength caused by foundation damage, and a variety of underpinning methods are used by modern foundation repair services. Mass concrete underpinning may be the oldest and simplest form of foundation underpinning, but it has a number of advantages that still cannot be matched by the most advanced underpinning techniques.

What is mass concrete underpinning?

In simple terms, mass concrete underpinning involves creating a secondary set of foundations beneath the existing set, which reinforces the structure as a whole and allows the reinforced foundations to support the weight of your home. To create these supplementary foundations without collapsing the house above, sections of earth are excavated from beneath the existing foundations in a precisely calculated order; once excavated, the void created is filled with concrete, which is allowed to harden and cure before the next section of earth is excavated.

What are the advantages of choosing mass concrete underpinning methods?

Simplicity is often a virtue, and the straightforward nature of mass concrete underpinning makes it a far less complicated process than more modern underpinning techniques, such as beam-and-base or mini-pile underpinning. It requires no specialised equipment or heavy excavation machinery to be used, making it an excellent choice for reinforcing the foundations of isolated, rural homes. Less specialised equipment also requires fewer specially qualified workers, so mass concrete underpinning can be cheaper than other underpinning methods in terms of labour costs.

Mass concrete underpinning can also save you money in another way. Since the earth beneath the foundations is removed in distinct sections, the house above remains very stable and can often be lived in while work is being carried out underneath, saving you money on alternate accommodation. The sheer quantity of concrete used to perform mass concrete underpinning also gives the newly reinforced foundations immense load-bearing strength, making it the best (and sometimes only option) for larger homes or particularly heavy homes constructed with traditional brick and block methods.

What are the disadvantages of choosing mass concrete underpinning methods?

Unfortunately, mass concrete underpinning is not a suitable reinforcement method for every set of foundations. If your foundations have suffered damage due to loose, shifting soils or rising groundwater levels, excavating large voids beneath your foundations to fill with concrete becomes practically impossible, as they are too likely to collapse before they are completed.

As you can imagine, manually excavating large quantities of soil and funnelling large amounts of liquid concrete beneath your foundations is also very labour intensive, and mass concrete underpinning generally takes significantly longer than beam and base or mini-pile underpinning. The deeper your foundations go, the more soil will have to be excavated to get beneath them, so the process can also be prohibitively time consuming and expensive if the foundations beneath your home are deeper than average.