What causes concrete slabs to sink?

Sinking is mainly caused by the weight of the slab, ground movement and changes over time. Two main factors affect slab stability:

1. Soil contraction
The composition of the soil (mainly clay) can lead to contraction under a given weight. A slab placed on hard ground will remain more stable than one placed on soft ground. Clayey soil can settle as it dries, causing the concrete to sink and crack.

2. Soil leaching
Precipitation and broken pipes can lead to soil leaching, creating empty spaces under the slab. This can cause gradual sinking and fissures. Animal burrows and excavation work near slabs can also cause voids to form.

How to prevent slab sinking

During dry periods, water your yard to make up for the loss of soil moisture. Sufficiently water trees to keep their roots from causing soil compaction under your slabs.

Solution for sidewalks
Injecting high-performance polymer at specific locations under the sidewalk will restore the solidity of its base, thus prolonging its useful life and its safe use.

Repair process

GeoFix uses an advanced technique, which involves injecting a high-resistance polymer under the slab to fill the voids. The result is a straight, level slab that is firmly affixed and supported, without the need for heavy machinery.

A special polymer developed by GeoFix

Working in partnership with Genyk, GeoFix developed a special polymer adapted to Quebec’s climate and different soil types. The result of several years of research and development in Quebec, our high-density polymer withstands the freezing and thawing cycles and retains its strength in water without disintegrating. Made partly from recycled materials, our lightweight polymer is effective enough for industrial use while being safe for the environment.

How does GeoFix’s solution work?

Our process in three steps:

  • Drill
  • Inject
  • Plug
Does GeoFix repair cracks in concrete?

Unfortunately not. Instead, we fix the cause of the cracks. However, be sure to check back as we will be adding this service in the future.

What can cause concrete slabs or floors to sink?

There are several reasons why slabs become uneven and cracks appear:

  • Poorly compacted soil
  • Water erosion (e.g., due to rain gutters)
  • Voids under the slab 
  • Backfill problems
  • Unstable soil under the building
  • Excess weight
Are the products GeoFix uses to lift concrete slabs ecoresponsible?

Yes, polyurethane foam products are ecoresponsible. Since the polymer is insoluble and hydrophobic, no chemicals are released into the surrounding water and soil. Also, its application does not create any construction debris.

Are GeoFix products guaranteed?

Yes, our products come with a 10-year warranty.

Are GeoFix products made in Quebec?

Yes, our products are custom-designed and produced by a Quebec manufacturer.

Are GeoFix products designed to withstand Quebec temperatures?

Our products are made with an exclusive polymer designed to withstand the temperature variations in our province and to give optimal results on the different types of soil found here.

Is GeoFix’s concrete lifting work durable?

Our foam systems will retain their original condition over the years, ensuring the durability of the work. As a general rule, our polymer will last as long as your concrete slabs or floors.

Can your concrete lifting work withstand extremely heavy loads?

Although very lightweight, our polymer can withstand very heavy loads. After being injected, our products increase the slab’s bearing capacity. Case in point: we lift grain silos. See how we solved the slab sinking problem of this silo (500 tons when filled) in this video:

Can GeoFix straighten paver stones or asphalt?

No, our method requires a solid concrete surface.

What types of concrete slab structures can you fix?
  • Attached garages
  • Basements
  • Crooked slabs
  • Detached garages
  • Driveways
  • Exterior entryways
  • Floors
  • Garden sheds
  • Gazebo slabs
  • Heat pump slabs
  • Hot tub slabs
  • In ground pool decking
  • Porches/Patios
  • Pool walkways
  • Sidewalks
  • Slab-on-grade homes
  • Stairs
  • Other
How do you control the lifting of the concrete?

GeoFix uses unique techniques and various tools, such as laser levels, to precisely control the lifting, levelling and stabilization of concrete slabs or floors.

Is the product you use similar to urethane insulation?

Not at all! The polymer formulas we use have been designed to withstand heavy loads due to their unique molecular structure. That is not the case for products used for insulation purposes.

How long do I have to wait to be able to walk or drive on the lifted, levelled or stabilized concrete slab or floor?

In most cases, there is no wait time. You will regain full use of your slab or floor immediately after the work is completed. However, keep in mind that it takes two hours for the polymer to reach its maximum strength.

How long does the concrete lifting work take?

Small and medium-sized residential projects can be completed in just a few hours. Larger industrial and commercial projects can take a few days.

Is concrete lifting expensive?

Our solution is very cost-effective. It is often less than half the cost of traditional rebuilding, not counting indirect costs such as earthwork, permits, etc.

Will your work damage my property?

Our method does not require any heavy equipment and leaves virtually no trace. We work within the perimeter of your concrete slab or floor and our approach does not cause any damage.

How does your approach impact the environment?

It has no impact on the environment. Since our polymer formulas are completely hydrophobic, they do not mix with the surrounding elements in any way. Also, since the material is inert, it does not pose any risk to the environment.

Why do concrete slabs sink?

Inadequate water management, poorly compacted soil (which tends to settle over time), erosion (a common factor) and animal burrows all create empty spaces under the slab. These voids cause the concrete to eventually crack and/or sink.

How do I prevent my concrete slabs from sinking?

If you have concrete slabs in your yard (e.g., a walkway around a pool), be sure to sufficiently water your yard during dry periods. You will limit the risk of the soil compacting when it loses moisture. The same goes for trees: water them generously so they do not need to extend their roots under the slabs to “drink,” which dries out the soil there.


Also, make sure that your land is sloping so that water runs off toward the street rather than toward your house. Adding rain gutters is another way to keep water from accumulating near your foundation.

What regions does GeoFix serve?

GeoFix’s services are available all across Quebec. Its experts are located in the following regions and cities:

  • Abitibi-Témiscamingue (Val-d’Or, Rouyn-Noranda, Amos, etc.)
  • Bas-St-Laurent (Kamouraska, Rimouski, Rivière-du-Loup, Témiscouata, etc.)
  • Centre-du-Québec (Bécancour, Drummondville, Nicolet, Victoriaville, etc.)
  • Côte-Nord (Baie-Comeau, Manicouagan, Sept-Îles, etc.)
  • Estrie (Granby, Cowansville, Lac-Mégantic, Magog, Sherbrooke, etc.)
  • Gaspésie
  • Gatineau 
  • Lanaudière (Joliette, Mascouche, Repentigny, etc.)
  • Laurentides (Mont-Tremblant, Saint-Sauveur, Val-Morin, etc.)
  • Laval
  • Montréal
  • North Shore of Montréal (Blainville, Sainte-Eustache, Mirabel, Saint-Jérôme, Terrebonne, etc.)
  • South Shore of Montréal (Boucherville, Brossard, Longueuil, Saint-Bruno, etc.)
  • Montérégie (Acton Vale, Beauharnois, Beloeil, Saint-Constant, Saint-Hyacinthe, Saint-Jean-sur-Richelieu, Salaberry-de-Valleyfield, etc.)
  • Mauricie (La Tuque, Louiseville, Shawinigan, Trois-Rivières, etc.)
  • Outaouais (Gatineau, Papineau, Chelsea, etc.)
  • Québec City
  • South Shore of Québec City (Beauce, Lévis, Montmagny, Saint-Georges, Sainte-Marie, etc.)
  • Saguenay–Lac-Saint-Jean (Jonquière, Chicoutimi, Alma, etc.)
What is concrete lifting and levelling?

An alternative to traditional methods, concrete lifting and levelling corrects sunken slabs in a way that avoids costly, complex and property-damaging demolition and reconstruction.

The procedure we use to bring a horizontal concrete component to the desired level preserves its useful life, reduces friction-related wear, fills voids underneath and maintains a safe environment. This method only minimally affects day-to-day activities, causing little inconvenience to users.

Why should you get your concrete slab lifted without delay?

To preserve its useful life, reduce friction-related wear and fill voids that have formed underneath.

GeoFix’s solution has many advantages:

  • Provides adequate support under the slab
  • Restores efficient drainage, preventing erosion
  • Complies with the building codes in force
  • Has only minimal impact on day-to-day activities
  • State-of-the-art equipment
  • Dust control
  • Environmentally responsible
  • Professional work covered by warranty
  • Available throughout Quebec
What can cause a concrete slab to sink?

One of the most common causes is a base with reworked soil around its periphery.

Spring floods and torrential rains can degrade the substrates under the slab. Freezing and thawing can also increase the risk of the slab sinking.

Inadequate water management causes damage and erosion.

Presence of machinery and significant vehicular traffic

The vibrations caused by stationary machinery or moving vehicles such as trucks or forklifts can cause the substrates under the slab to move, creating voids and causing the slab to shift.

Why fill voids under a concrete slab?

Concrete can withstand compression but not tension caused by a lack of support. GeoFix’s solution gives the slab support, preventing stress and weakening.


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