Void Filling
Underground voids can form beneath buildings and infrastructure due to washout, dissolved materials, collapsed drains, or old mine workings. These voids pose a significant risk of sudden ground collapse. Our void filling service uses controlled injection techniques to safely fill these spaces and prevent further settlement.
Key Benefits
Sub-surface void detection
Controlled injection process
Prevents sudden collapse
Suitable for all void types
Non-destructive method
Rapid completion times
Is Void Filling Right for You?
Ideal for
Known or suspected underground voids beneath a property
Collapsed or damaged drainage causing ground washout
Properties built over old mine workings or chalk solution features
Sudden or localised ground depression
Preventative treatment where voids have been detected by survey
Not suitable for
General subsidence not caused by voids (resin injection may be better)
Structural cracking without evidence of sub-surface voids
Surface water drainage problems (drainage solutions needed)
How It Works
Detection
Ground penetrating radar and other methods to locate and map voids.
Planning
Injection plan designed based on void size, location, and cause.
Filling
Controlled injection of grout or resin to fill the void safely.
Verification
Post-treatment scanning confirms complete void filling.
Void Filling Across Hertfordshire
Click a location for local details.
Frequently Asked Questions
How do you find voids under a building?
We use ground penetrating radar (GPR) to map sub-surface conditions non-destructively. This is supplemented with dynamic cone penetrometer testing and trial pits where needed to confirm void size, depth, and extent.
Is void filling disruptive?
No. Injection is carried out through small surface-drilled holes with no excavation. Most residential jobs are completed in 1–2 days with minimal noise and no heavy plant.
What happens if a void isn't filled?
The ground above can collapse suddenly and without warning, causing severe structural damage. Voids rarely stabilise on their own — they tend to grow as water continues to wash out surrounding material.
Can void filling be done under an occupied building?
Yes. The injection process is controlled and monitored in real time, making it safe to carry out beneath occupied residential and commercial properties.
How much does void filling cost?
Costs depend on the void size and depth. Small localised voids from drain collapse typically cost £2,000–£5,000. Larger voids from washout or mine workings cost more. We provide a fixed quote after survey.
What material is used to fill voids?
We use geopolymer resin for smaller voids and cementitious grout or foamed concrete for larger cavities. The material is chosen based on void size, ground conditions, and structural requirements.
Free Void Filling Survey
No obligation quote