What is Underpinning?
When Do You Need Underpinning?
Foundation issues rarely resolve on their own. If left untreated they can cause severe structural damage and costly repairs. Warning signs that underpinning may be required include:
- Cracks in walls, ceilings, or brickwork.
- Doors and windows that jam or no longer close properly.
- Floors that slope or feel uneven.
- Noticeable sinking of part of the house or extension.
- Gaps opening between skirting boards and floors or between walls and ceilings.
Applications of Underpinning
- Subsidence repair for homes affected by sinking foundations.
- Cracked wall stabilisation where soil movement is the cause.
- House extensions that require deeper or stronger foundations.
- Reactive clay and sandy soils where shrink-swell or erosion has reduced bearing capacity.
- Footing reinforcement for older properties with shallow or degraded foundations.
Underpinning Methods We Use
Different properties and soil conditions call for different solutions. At AGS we use a range of underpinning methods, each engineered for long-term stability:
Cement-based or chemical grout is injected beneath existing footings to fill voids, bind loose soils, and restore bearing strength. This technique is particularly effective where soil has eroded, washed out, or lost capacity through shrink–swell movement. It strengthens the ground while supporting the weight of the structure above.
Lightweight polyurethane resin is injected under the foundation, where it expands to compact the soil and gently lift sunken areas back into position. This method is fast, clean, and precise, making it ideal for occupied homes. It requires minimal excavation and can often be completed in a single day with very little disruption.
Galvanised steel ground screws are driven into stable strata below the existing foundation line. Once installed, they act as permanent supports that transfer the building load onto stronger soils deeper underground. Ground screws are a versatile option for sandy or reactive clay sites, and are particularly useful for underpinning extensions or retrofitting additional support to older homes.
Benefits of Professional Underpinning
- Stops ongoing settlement and prevents future movement.
- Permanent repair for cracked walls and damaged footings.
- Less invasive than full foundation replacement.
- Customised solutions for Perth’s clay and sandy soils.
- Backed by engineered designs and certified installation.
Who We Work With
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Do not let foundation problems compromise the safety and value of your home. Advanced Ground Solutions provides engineered underpinning tailored to Perth’s soils, ensuring lasting stability and peace of mind.
- Perth-Based Underpinning Specialists.
- Permanent Solutions for Sinking Foundations.
- Certified Methods: Grout, Resin, and Screw Piles.
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FAQ
What is the difference between grout injection and polyurethane resin injection underpinning?
Grout injection uses cementitious or chemical materials to fill voids and strengthen soil. Polyurethane resin injection uses expanding polyurethane foam to lift and support foundations with precision.
How do I know if my house needs underpinning?
Common signs include cracked walls, uneven floors, or parts of the house sinking. An inspection will confirm whether underpinning is required.
Can underpinning fix subsidence in clay soils?
Yes. Underpinning is commonly used in Perth’s clay soils where shrink-swell movement causes foundations to drop.
Is underpinning disruptive to my home?
Modern injection and screw pile systems are far less invasive than traditional underpinning, with minimal disturbance to gardens or interiors.
How long does underpinning last?
Underpinning solutions are designed as permanent repairs and should last the lifetime of the building.
What is the difference between grout injection and polyurethane resin injection underpinning?
Grout injection uses cementitious or chemical materials to fill voids and strengthen soil. Polyurethane resin injection uses expanding polyurethane foam to lift and support foundations with precision.