Concrete Void Filling and Soil Stabilization in Calgary
FOAMExperts provides concrete void filling and soil stabilization in Calgary for suitable residential, commercial, and industrial slabs. We inject polyurethane material beneath concrete to fill accessible spaces, restore support, and reduce slab movement.
Some projects require support without a major change in elevation. Others may need both void filling and controlled concrete lifting.
What Is a Void Beneath Concrete?
A concrete void is an empty or unsupported space beneath a slab. It can form when soil settles, washes away, or moves after the concrete has been installed.
The concrete may remain in place for some time, even though part of the slab no longer has full support.
Voids may develop beneath:
- Driveways
- Sidewalks
- Patios
- Pool decks
- Garage floors
- Entrance slabs
- Warehouse floors
- Parking areas
- Loading zones
- Equipment pads
Leaving an unsupported slab untreated may allow further movement, cracking, or edge damage.
Signs of a Void Beneath a Concrete Slab
A void may be present when you notice:
- Hollow sounds beneath the concrete
- Rocking or moving slabs
- Repeated settlement
- Gaps beneath exposed edges
- Cracks around unsupported areas
- Water flowing beneath the concrete
- Soil washed out beside the slab
- Concrete that moves under vehicles or foot traffic
- Unsupported slab corners
- Low sections near drains or foundations
These signs do not confirm the size or depth of a void. An inspection is required before recommending treatment.
Causes
What Causes Voids Beneath Concrete?
Water Erosion and Washout
Water can carry soil and fine material away from beneath concrete. Common sources include:
- Downspouts
- Snowmelt
- Poor grading
- Irrigation systems
- Plumbing leaks
- Damaged drains
- Concentrated runoff
Poor Soil Compaction
Soil placed during construction may compress over time if it was not compacted correctly. This can leave a gap beneath the slab.
Utility Trenches
Soil placed over water, gas, sewer, or electrical trenches may settle differently from undisturbed ground.
Freeze-Thaw Movement
Moisture beneath exterior concrete can freeze and expand. Repeated seasonal movement may weaken the supporting base.
Disturbed or Backfilled Soil
Concrete installed beside foundations, retaining walls, pools, or previous excavations may sit over disturbed ground.
Animal Burrows
Animal activity may remove or loosen soil beneath concrete, especially near exposed slab edges.
Underground Leaks
A leaking pipe or drainage system can soften soil and cause continued washout. The leak may need to be repaired before foam injection begins.
Void Filling vs Concrete Lifting
Void filling, slab stabilization, and concrete lifting are related services, but they do not have the same purpose.
Void Filling
Void filling places polyurethane material into accessible spaces beneath a concrete slab.
Its main purpose is to restore support.
A significant change in slab elevation may not be required.
Slab Stabilization
Slab stabilization aims to reduce rocking or movement by supporting the concrete from below.
The slab may remain at its current elevation.
Concrete Lifting
Concrete lifting raises a settled slab. Polyurethane foam fills accessible gaps and applies controlled upward pressure.
Soil Stabilization
Soil stabilization may involve injecting material into weak, loose, or disturbed ground beneath or near the slab.
The correct treatment depends on:
- Slab condition
- Void depth
- Soil type
- Settlement cause
- Required elevation
- Access
- Nearby structures
- Expected loads
One project may require both stabilization and lifting.
Work Process
How Polyurethane Void Filling Works
Inspect the Concrete
We assess the slab condition, cracks, movement, drainage, visible gaps, and surrounding ground.
Identify the Likely Void Area
Measurements, visual signs, hollow sounds, and slab movement may help identify unsupported areas.
Additional testing or specialist review may be needed for complex sites.
Plan the Injection Points
Small access holes are positioned to reach the required areas beneath the concrete.
Inject Polyurethane Material
The material enters accessible voids and expands beneath the slab.
Injection is completed in controlled amounts to limit unwanted slab movement.
Monitor the Slab
The technician watches the concrete, joints, walls, drains, and nearby features throughout the process.
Seal the Injection Holes
The access points are sealed after the work. The patch colour may not exactly match the existing concrete.
Complete a Final Inspection
The slab support, movement, elevation, and surrounding work area are reviewed.
Deep Foam Injection
Deep foam injection places polyurethane material below the immediate underside of a slab to reach deeper weak areas or soil zones.
This method may be considered when:
- Voids extend below the slab base
- Soil beneath the concrete has lost strength
- Settlement continues after surface-level support is restored
- A deeper injection plan is required
- Site access limits excavation
Deep foam injection is not suitable for every soil or structural condition.
The assessment may need to consider:
- Injection depth
- Soil type
- Groundwater
- Underground utilities
- Nearby foundations
- Expected loads
- Geotechnical conditions
Publish this section only if FOAMExperts genuinely provides deep foam injection and has suitable equipment, training, and project experience.
Residential Applications
Polyurethane void filling may be considered beneath suitable residential concrete such as:
- Driveways
- Private sidewalks
- Patios
- Pool decks
- Garage floors
- Garage aprons
- Entrance slabs
- Steps
- Selected basement slabs
Residential assessments should consider drainage, downspouts, landscaping, nearby foundations, utilities, and access.
Commercial Applications
Commercial void filling may be used beneath suitable concrete around:
- Retail properties
- Offices
- Condominium buildings
- Apartment buildings
- Walkways
- Parking areas
- Loading zones
- Warehouse floors
- Service areas
Commercial projects may require traffic control, phased work, operating-hour planning, and written documentation.
Industrial Applications
Industrial void filling may be considered for suitable:
- Warehouse floors
- Manufacturing slabs
- Distribution centres
- Loading bays
- Equipment pads
- Workshops
- Service areas
Industrial work requires additional review of slab thickness, reinforcement, equipment, utilities, loads, and operating requirements.
When Void Filling May Be Suitable
Void filling may be considered when:
- Accessible gaps exist beneath the slab
- The concrete remains structurally sound
- The slab rocks or sounds hollow
- The main goal is to restore support
- Nearby structures allow controlled injection
- The source of water or erosion can be managed
- The proposed material suits the expected load
Final suitability depends on a site-specific assessmen
Limitations
Limitations of Foam Injection
Additional work may be required when the site has:
Active Water Leaks
Plumbing, irrigation, pool, or drainage leaks should be repaired before injection where possible.
Major Drainage Problems
Poor grading, blocked drains, or uncontrolled downspouts may continue to wash soil away.
Severe Concrete Damage
Broken, deteriorated, or weak slabs may need replacement rather than support from below.
Structural Foundation Movement
A structural engineer or qualified foundation specialist may be required.
Deep or Complex Ground Failure
Some soil conditions may require:
- Geotechnical assessment
- Excavation
- Compaction
- Drainage repair
- Underpinning
- Pier systems
- Concrete replacement
Underground Utilities
Known utility lines, drains, heating systems, and pipes must be considered before drilling or injection.
FOAMExperts should explain when polyurethane injection is not the right treatment.
How Long Does Void Filling Last?
There is no single service life that applies to every project.
Long-term performance depends on:
- Cause of the void
- Soil movement
- Drainage
- Water leaks
- Slab condition
- Foam specification
- Expected loads
- Injection depth
- Nearby construction
- Ongoing maintenance
Future movement may occur if erosion, weak soil, or another underlying cause continues.
Void Filling and Soil Stabilization Cost Factors
Project cost depends on:
- Slab size
- Void depth
- Void volume
- Foam specification
- Amount of material required
- Number of injection points
- Injection depth
- Interior or exterior access
- Expected loads
- Utility locations
- Site restrictions
- Commercial or industrial requirements
- Additional testing
- Drainage repairs
- Project documentation
An accurate quote normally requires photographs, measurements, and a site assessment.
FAQ
Void Filling and Soil Stabilization FAQs
Does void filling always lift the concrete?
No. Void filling may restore support without significantly changing the slab elevation.
How do you know whether a void exists?
Visible gaps, hollow sounds, rocking slabs, settlement, and water washout may indicate a void. Further inspection may be required to confirm the condition.
Can polyurethane foam stabilize weak soil?
Some polyurethane systems may be suitable for specific soil-stabilization applications. Suitability depends on the product, soil, depth, loads, and site conditions.
Can foam injection repair a foundation?
Ordinary slab lifting and void filling should not be presented as complete structural foundation repair. Foundation movement may require engineering and specialist assessment.
Will the injection holes remain visible?
The holes are sealed after the work. However, the patch colour and texture may not perfectly match the existing slab.
Can voids return after treatment?
New voids may form if water erosion, leaks, soil movement, or another underlying problem continues.
Is excavation required?
Many polyurethane injection projects require limited drilling rather than full excavation. However, excavation may be required for drainage, utility, structural, or severe ground problems.
How long does void filling take?
Project time depends on the slab area, void depth, access, injection requirements, and site conditions.
Is void filling cheaper than concrete replacement?
It may cost less in suitable cases. The correct option depends on slab condition, void size, access, expected loads, and the cause of settlement.
Request a Void-Filling Assessment
- Property address
- Property type
- Concrete surface
- Approximate dimensions
- Wide photographs
- Close-ups of visible gaps
- Areas that move or sound hollow
- Drainage concerns
- Known plumbing or irrigation leaks
- Utilities or in-floor systems
- Expected vehicle or equipment loads
- Access restrictions
- Previous repair details