Underpinning involves installing deeper footings beneath an existing foundation to stabilise and strengthen the structure. Any large cracks in your property sign that your house may require underpinning.
Homeowners may initially ignore the problem since they assume it is a minor structural defect or cosmetic issue. However, any homeowner would be alarmed if their home starts to show visible cracks, especially if they grow more significant over time. It’s a sign that something is wrong with your house’s foundation, and you will want to act quickly before it worsens. For homeowners who want to fix the issue immediately, there are tips and tricks you can try to make your home safe.
If you own a house, you know the foundation is the only rock-solid thing about it. At some point, however, that foundation can no longer hold up the home above it. This is when a homeowner needs to call in an expert to perform underpinning. But what exactly is underpinning? And what does it have to do with supporting a foundation?
When situations require underpinning a house?
There are several reasons why footings sink into the soil. Water and wind can create gaps between footings, disturbing the centre of gravity. This imbalance causes the structure to sink further into the soil. Underpinning is a technique used in fixing problems associated with the movement of a structure’s footings. There are several reasons why footings sink into the soil.
What is underpinning?
The construction process of strengthening the foundation by constructing extra concrete or steel footings to stabilise, reinforce, or raise the existing footings is known as underpinning a house, residential dwelling, or even a commercial building.
In order to support your home on soil that is more solid than the soil it presently rests on, underpinning is a building process that involves adding additional footings next to and under your home.
When is underpinning a house necessary?
You need underpinning when the structure is being extended: Underpinning is needed to strengthen the existing foundation because the extension’s added weight may cause it to buckle.
The soil beneath the foundation is unstable: If the soil is overly soft or has insufficient drainage, this may occur. The structure may sustain significant damage if the foundation begins to settle and break. The soil will be stabilized and won’t settle anymore thanks to underpinning. Underpinning a house is necessary when;
- Soil erosion: This can occur when there is poor drainage in the area around the home.
- Inadequately compacted soil before construction: Before anything is built on top of soil that has been backfilled after being removed from a construction site, it must be thoroughly compacted.
- Natural disasters: The structural effects of earthquakes, floods, droughts, and sinkholes are all possible.
The surrounding large trees have soaked up all the moisture: This may cause the earth to shrink and dry out, leaving gaps beneath the foundation. If the foundation begins to sag into these spaces, you’ll run into problems.
Underpinning comes in a variety of forms, each with unique benefits and drawbacks
Mass concrete underpinning
Entails digging a hole around the foundation’s edge and filling it with concrete. The concrete will fill any holes in the soil, which will also serve as the building’s sturdy foundation.
Mini-piled underpinning
Piles of modest diameters are driven into the ground. They are attached to central support, which gives the foundation solidity. In locations where the soil is too soft for conventional underpinning techniques, mini-piled underpinning is frequently used.
Beam and base underpinning
This method entail excavating around the foundation’s edge and setting up a concrete beam to cover the opening. While the base stops soil from entering the excavation, the beam supports the foundation.
Helical screw piering
At a little slant, steel piers are screwed into the ground. The piers are attached to central support, which gives the foundation solidity.
Reasons for underpinning
There are numerous justifications for why underpinning is necessary. To better comprehend the special utility of underpinning, consider the following list.
If a building needs to be underpinned, for example:
- The original foundation cannot support the structure since it is not stable or strong enough.
- The structure’s original purpose has changed, necessitating foundational reinforcement.
- The soil is unable to support the structure’s weight.
- The building is getting another story. Thus deeper footings are needed to accommodate more load-bearing capacity.
- Repairing or reinforcing is more affordable than purchasing new.
- The structural security of the building has been endangered by earthquakes, droughts, floods, or other natural disasters.
Which circumstances cannot be resolved by underpinning?
When the soil’s moisture level varies unevenly, footing movements that are likely to reverse typically happen. Clayey soils or slab heave frequently experience this. For slab heave-related problems, underpinning is not advised. The movement produces an impact that can be undone. Underpinning shouldn’t typically be used to resolve problems caused by the reactive movement of clay.
10 things everyone ought to know about the underpinning foundation
- There are several different types of underpinning. The most frequent method of underpinning a pier is to move the support for a wall’s footing to a deeper level.
- While the old foundation is being replaced, a wall or column might be supported by needle beams that bridge between temporary foundations.
- Underpinning can be done using a variety of pile systems. It involves using micro piles, either drilled through existing foundations or fastened to the current building using retrofit pile caps.
- A structure that is underpinned is in danger of destruction due to the approach of underpinning construction.
- To transfer weights to the earth through the new foundation elements, the existing structure had to flex, and the underpinning had to settle.
- Damage will happen if the structure moves sufficiently large or unevenly.
- The contractor is held responsible for any damages if the underpinning did not operate as intended.
- The risks to the owners and occupants of neighboring buildings are increased by improperly planned or improvised underpinning.
- Underpinning systems are safety precautions that shield the public and construction employees from potential dangers.
- To support your home on soil that is more solid than the soil it presently rests on. Underpinning is a building process that involves adding additional footings next to and under your home.
Does your property need underpinning?
A visual evaluation and a movement/subsidence examination should determine whether your property needs underpinning. There are numerous potential causes for why underpinning might be necessary. Uneven soil moisture levels, which cause reactive clay flooring to swell and contract unevenly, are a common reason for underpinning. As a result, there is unequal movement inside the house, which may cause undermining.
Final Thoughts:
When problems with the soil under a foundation are severe enough, underpinning is usually the only option to restore the home’s stability and prevent costly damage. The work that must be done is fairly involved; this is why hiring a company for underpinning services is advisable.
In conclusion, the three most viable solutions for problematic soil include: Moving a house to a different spot in your yard. Crawling under and supporting the foundation with piers. Digging out the existing soil and replacing it with new soil. There are some decisions you can make by yourself, while others require help from a professional. Always consult an engineer when you have any questions concerning your foundation.
