Cracks vs Joints vs Potholes What Must Be Repaired Before Industrial Epoxy Flooring?
A factory floor has cracks.
Another area has a broken joint.
A forklift aisle has developed a pothole.
Can the contractor simply fill everything with epoxy mortar and coat the entire floor?
Not necessarily.
These three defects can look similar from a distance, but they represent very different concrete conditions.
A crack is normally an unplanned break in the concrete.
A joint may have been intentionally created to control or accommodate movement.
A pothole is an area where concrete has physically broken down and material has been lost.
The correct repair therefore starts with classification — not with the repair material.
What Must Be Repaired Before an Industrial Epoxy Floor Is Installed?
Cracks, damaged joints, potholes, spalled concrete, loose concrete and significant level defects should be assessed before the final industrial epoxy system is installed.
But they should not all receive the same repair.
Stable cracks can often be prepared and repaired using a compatible rigid or semi-rigid repair approach.
Moving cracks need the movement and underlying cause investigated. Simply filling an active crack with rigid material can allow the crack to reflect through the new floor.
Concrete joints must be identified by function. Broken joint shoulders can be rebuilt, but movement joints should not simply be buried under continuous rigid epoxy.
Potholes and spalled areas should be cut or prepared back to sound concrete, cleaned and rebuilt with a repair material appropriate to the depth and final flooring system.
If the floor is also uneven, repair depth and final epoxy thickness should be treated as separate questions.
Know What You Are Repairing Before Choosing the Product
What Is the Difference Between a Crack, Joint and Pothole?
An unplanned fracture or separation in the concrete.
Possible causes include drying shrinkage, thermal movement, settlement, restraint, overload or structural movement.
The key question is: is it stable, or is it still moving?
A planned separation or discontinuity within the concrete floor.
Different joint types exist to control cracking, separate placements or accommodate movement.
The key question is: what was this joint designed to do?
A local area where concrete has broken, spalled or disappeared.
Forklift impact can repeatedly enlarge the weak perimeter.
The key question is: where does the unsound concrete end?
A crack may need filling. A joint may need to remain functional. A pothole may need rebuilding.
Calling all three “cracks” can produce the wrong repair.
The First Question Is Not “What Do We Fill It With?”
The first question is: why did the concrete crack?
ACI identifies multiple causes of concrete cracking, including: drying shrinkage, thermal change, settlement, restraint, overload and insufficient or inappropriate jointing.
That means two cracks with almost the same width may have completely different causes.
Shrinkage Crack
May form as concrete changes volume during drying. A mature, dormant crack may behave differently from active movement.
Settlement Crack
May indicate movement of the slab or supporting material. Surface filling does not correct ongoing settlement.
Load-Related Crack
May be associated with traffic, machine loads, foundation behaviour or slab capacity.
Thermal Crack
Temperature-related movement can open or close cracks over time.
Restraint Crack
Concrete movement that is restricted by another building element can create cracking.
Joint-Related Crack
Cracks may form near, beside or between joints when slab movement does not occur exactly as intended.
A crack assessment should therefore consider:
Stable Crack vs Moving Crack: Why the Repair Changes
| Crack Condition | What It May Mean | Typical Repair Direction | Main Caution |
|---|---|---|---|
| Old Dormant Crack | Crack appears stable and no meaningful ongoing movement is identified | Prepare, clean and repair with a compatible rigid or semi-rigid method according to system | Confirm the crack is genuinely stable |
| Moving Crack | Width changes, movement occurs or cause remains active | Movement-tolerant detail or further diagnosis | Rigid repair may crack again |
| Crack Near a Joint | Movement or failed joint detailing may be involved | Assess together with joint | Do not treat the crack while ignoring the joint function |
| Wide / Displaced Crack | Possible structural or foundation movement | Engineering review may be needed | Do not hide under coating |
| Wet Crack | Possible water entry or moisture source | Diagnose water source before final flooring | Ordinary crack filling does not stop every water problem |
ACI’s crack-repair guidance includes several possible methods, including epoxy injection, routing and sealing, grouting, dry packing and other techniques.
The existence of these multiple methods is itself an important point.
There is no single repair method appropriate for every crack.
Do not decide the crack-repair material until you know whether the crack is stable, moving, wet, load-related or structurally significant.
A Joint Is Not Automatically a Defect
Many factory floors are supposed to have joints.
ACI distinguishes several types.
Contraction Joint
Created to form a weakened plane so cracking from dimensional change occurs in a more controlled location.
Construction Joint
An intentional interface between separate concrete placements.
Isolation Joint
Separates adjacent concrete sections so relative movement can occur.
Expansion Joint
Provides separation that allows adjacent sections to accommodate dimensional movement.
Cold Joint
A discontinuity that can result when concrete placement is delayed enough to prevent full intermingling and bonding.
Damaged Joint
A previously functional joint whose edges or surrounding concrete have broken under service traffic.
The goal is not to make every joint disappear.
The goal is to restore the damaged concrete while respecting the joint’s intended function.
Why Do Industrial Floor Joint Edges Break?
Joint shoulders are vulnerable to repeated wheel impact.
Imagine a small chip at the edge of a joint.
The next forklift wheel reaches that opening.
Instead of rolling across a supported flat surface, the wheel hits an exposed edge.
The impact can remove more concrete.
The defect gets wider.
Then the next wheel hits an even larger edge.
This creates a progressive damage cycle.
Small Chip
The initial edge loses a small piece of concrete.
Wheel Impact
Forklift wheels strike the unsupported edge.
More Spalling
The shoulder breaks back further.
Vehicle Vibration
The larger gap creates additional wheel shock and operator discomfort.
Repair Gets Larger
Ignoring a small joint defect can increase the amount of concrete that later needs rebuilding.
Overlay Risk
Coating directly over the damaged edge does not restore the missing load-supporting concrete.
A proper joint repair may therefore involve:
Why You Should Not Just Pour Epoxy Into a Pothole
A pothole is normally not just an empty space.
The surrounding concrete may also be: weak, cracked, delaminated, contaminated, or partially detached.
If repair material is placed only into the visible hole, it may bond to concrete that was already about to fail.
Inspect
Identify the visible damage and surrounding weakness.
Remove
Take out loose and unsound concrete.
Define
Create a sound repair boundary.
Clean
Prepare the repair area for reliable bonding.
Rebuild
Install the appropriate repair material to required depth.
Overlay
Install the final wearing floor after the repair is ready.
The repair material rebuilds the damaged substrate. The epoxy overlay creates the final wearing surface.
Those are related, but separate, functions.
A Depression Is Not Just a Thick Pothole
Some floors do not have a sharp pothole.
Instead, they have large sunken areas, hollows, low spots or uneven transitions.
These defects can cause:
Forklift Vibration
Wheels drop and climb through level variation.
Ponding Water
Low areas can retain cleaning water or process liquids.
Trip Hazards
Uneven transitions can affect pedestrian movement.
Trolley Instability
Small wheels can react strongly to abrupt level variation.
Uneven Coating Build
Trying to “fill everything” with a thin finish creates uncontrolled thickness.
Drainage Problems
Incorrect levels can redirect water away from intended drainage.
Floorzy currently positions Screed Plus for this type of correction.
Its current published range is approximately 5–50 mm per layer.
That gives a useful distinction:
Levelling thickness and final epoxy-floor thickness are separate specifications.
A 20 mm depression should not automatically be filled by making the final epoxy coating 20 mm thick.
Why Forklifts Make Small Floor Defects Bigger
A crack, joint chip or pothole that seems minor to a pedestrian can behave differently under repetitive industrial wheels.
Forklifts create several types of loading.
Rolling Load
Repeated passes apply the same wheel load to the same floor routes.
Impact
A wheel dropping into a pothole or damaged joint creates impact at the edge.
Turning
Tight turns produce lateral shear across the floor surface.
Braking
Vehicle deceleration can increase stress in concentrated areas.
Hard Wheels
Smaller, hard contact surfaces can create high local stress.
High Frequency
A defect crossed hundreds of times per shift can deteriorate rapidly.
This is why joint repair and pothole repair should be treated as operational maintenance issues — not only appearance issues.
Which Floor Defects Need Engineering Review Before Epoxy?
An epoxy contractor should not claim that a coating will permanently solve every structural concrete problem.
Engineering review may be appropriate when defects include:
A resin overlay does not increase the structural capacity of an inadequate slab simply because the coating itself has high compressive strength.
Structural concrete, subgrade and machine foundations remain separate engineering questions.
What Is the Correct Sequence Before Industrial Epoxy?
Survey
Map cracks, joints, potholes and levels.
Classify
Determine what each defect actually is.
Prepare
Remove coatings, weak concrete and contaminants where required.
Repair
Treat cracks, joints and potholes individually.
Level
Correct major depressions or height variation.
Overlay
Install the final system after the substrate is ready.
Floorzy’s current Interior Semi Gloss installation process already follows this general philosophy.
Its published process includes: site assessment, mechanical preparation, crack and defect repair, primer, epoxy build, and controlled curing.
The critical point is that repair comes before the final finish.
When Does Screed Plus Become Relevant?
Floorzy currently positions Screed Plus as a two-component epoxy mortar / self-levelling screed for damaged and uneven concrete.
Current published data includes:
| Parameter | Current Floorzy Published Value |
|---|---|
| System Type | Two-component epoxy mortar / self-levelling screed |
| Application Thickness | 5–50 mm per layer |
| Compressive Strength | >60 N/mm² at 7 days |
| Flexural Strength | >18 N/mm² |
| Adhesion to Concrete | >1.5 N/mm² |
| Walk-On | Approximately 4–6 hours at 25°C |
| Overcoat | Approximately 12–24 hours |
| Full Structural Strength | 7 days |
Potential applications include:
When Should the Final Epoxy Overlay Be Installed?
The final resin flooring system should be installed after the concrete has been brought to an appropriate condition for that system.
That normally means:
Then the final system can be selected according to use.
For example:
General Factory Area
Floorzy Interior Semi Gloss may be appropriate for suitable general industrial interiors.
Heavy Forklift Route
PrimeShield Heavy Load may be more appropriate for demanding mechanical traffic.
Exterior Area
Outdoor loading docks, ramps and yards require an exterior-oriented system.
ESD Area
Electronics facilities may require a tested electrostatic-control floor system.
Car Park
Vehicle, pedestrian and wet-condition requirements change the finish design.
Uneven Substrate
Screed or levelling may be required before any of the final systems are installed.
What Should Happen to Each Defect Before Epoxy?
| Observed Defect | First Question | General Direction | Should You Simply Coat Over It? |
|---|---|---|---|
| Hairline Stable Crack | Is it dormant? | Prepare and repair with a compatible method where required | No, not without assessment |
| Active Moving Crack | Why is it moving? | Movement detail or further engineering diagnosis | No |
| Wide Displaced Crack | Is structural movement involved? | Engineering assessment may be necessary | No |
| Sound Control Joint | Does it still need to move? | Preserve joint function in final detail | Do not blindly bury it |
| Broken Joint Shoulder | How much edge concrete is unsound? | Remove weak material, rebuild shoulder, restore joint detail | No |
| Small Pothole | Where is the sound boundary? | Prepare and rebuild before overlay | No |
| Deep Pothole | How deep is the deterioration? | Deep repair or screed before final flooring | No |
| Large Depression | Is it wear, settlement or level error? | Level correction or engineering review depending on cause | Do not use finish coat as leveller |
| Dusty Weak Surface | How deep is the weak concrete? | Mechanical preparation to sound substrate and appropriate treatment | No |
| Structural Settlement | Why is the slab moving? | Engineering correction | No |
How Should These Common Floor Problems Be Approached?
Thin Crack Through a Dry Warehouse
The crack has been visible for several years and appears unchanged.
Crack Opens Every Few Months
The same line keeps reopening after local repair.
Forklift Joint Has Chipped Edges
Every forklift pass produces a noticeable impact at the joint.
Warehouse Has a Deep Pothole
The centre of the pothole is approximately below the surrounding floor and the edges continue breaking.
Large Area Is 15–20 mm Low
Forklifts bounce through a broad depression.
Crack Has Vertical Displacement
One side of the crack is visibly higher than the other.
10 Things Not to Do Before Installing Epoxy
Some lines may be movement joints or active cracks.
A topcoat does not rebuild missing load-bearing concrete.
Loose concrete may extend beyond the obvious opening.
Repair thickness and wearing-floor thickness are separate design decisions.
Displacement can indicate a more serious underlying condition.
A resin coating should not be expected to solve every leakage problem.
Weak, dusty or contaminated boundaries can reduce repair reliability.
The same defect can receive very different mechanical stress inside a high-traffic aisle.
Movement can simply reappear through the new floor.
Resin flooring does not replace structural engineering repair.
18 Questions to Ask Before Approving Concrete Repairs
Do not ask only: “What product will you use to fill this?”
Ask: “What is this defect, why did it happen, and how will your repair deal with that cause?”
Why Cracks and Joints Should Not Be Treated as the Same Thing
ACI distinguishes contraction, isolation, expansion, construction and cold joints. A contraction joint creates a weakened plane to regulate the location of cracking. An isolation joint permits relative movement. A construction joint is an intentional interface between concrete placements. View ACI guidance
ACI guidance covers crack causes, evaluation and multiple repair techniques, including epoxy injection, routing and sealing, grouting, dry packing and overlays. This supports the central principle that crack treatment depends on the actual crack condition. View ACI reference
Floorzy’s current industrial-floor repair process begins by checking the crack type, joint condition, surrounding concrete and traffic before recommending a repair method. View Floorzy repair page
Related Floorzy Technical Guides
Floorzy’s dedicated repair service page for cracked and damaged industrial concrete.
For potholes, damaged concrete, depressions and level correction before final flooring.
Floorzy’s general industrial epoxy overlay for suitable prepared concrete.
For demanding forklift and machinery traffic after the substrate has been repaired.
For peeling, wear, blistering and previously failed resin flooring.
Send your factory location, floor photos, traffic and damaged-floor area.
Do Not Choose the Repair Material Until You Know What the Defect Is.
Send Floorzy wide photographs, close-up photographs, a short video, factory location, approximate damaged area, forklift traffic and information about whether the crack or damaged joint has been repaired before.
The objective is to determine whether the floor needs crack repair, joint rebuilding, pothole rebuilding, levelling, a movement detail, or further structural investigation before the final overlay is installed.
Frequently Asked Questions
Should cracks be repaired before epoxy flooring?
Cracks should be assessed before epoxy flooring. Stable cracks can often be repaired using a compatible repair method. Moving or structurally significant cracks may require a different detail or engineering assessment.
Can epoxy flooring simply cover a crack?
A coating can cover the visible line, but if the underlying crack continues moving, the movement may reflect through the new floor. Diagnosis should come first.
What is a stable concrete crack?
A stable or dormant crack is one that is not showing meaningful ongoing movement under the conditions being assessed. Its cause and history should still be reviewed.
What is an active concrete crack?
An active crack is one that continues to experience movement or change. Rigidly repairing an active crack without addressing the movement can lead to recurrence.
How can I tell whether a crack is moving?
Look at its history, whether previous repairs have reopened, changes in width, vertical displacement, location and surrounding slab behaviour. Important cracks may require monitoring or engineering review.
Can epoxy injection repair concrete cracks?
Epoxy injection is one recognised concrete crack-repair method. Its suitability depends on the crack type, access, movement and structural objective. It is not the correct method for every crack.
Should movement cracks be filled with rigid epoxy?
Not automatically. Where movement continues, the detail needs to account for that movement. A rigid repair can crack again if the underlying movement continues.
What if the crack has vertical displacement?
A noticeable height difference between the two sides can indicate settlement, movement or another more serious slab condition. Further investigation may be required before resurfacing.
Can structural cracks be hidden under epoxy flooring?
No. A resin floor should not be used as a substitute for structural diagnosis or structural repair.
What is the difference between a crack and a joint?
A crack is normally an unplanned fracture. A joint is typically an intentional separation or discontinuity created during design or construction.
What is a control or contraction joint?
ACI describes a contraction joint as a formed, sawed or tooled groove that creates a weakened plane to regulate where cracking from dimensional change occurs.
What is a construction joint?
A construction joint is an intentional interface between separate concrete placements.
What is an isolation joint?
An isolation joint separates adjacent sections so relative movement can occur between them.
What is an expansion joint?
An expansion joint provides a separation that allows adjacent concrete sections to accommodate dimensional movement.
Should concrete joints be filled before epoxy?
Not every joint should simply be filled and buried. The joint type and intended movement should first be understood.
Can an epoxy coating go continuously across a movement joint?
A rigid continuous coating across an active movement joint can be vulnerable to cracking as the joint moves. The final detail should accommodate the intended movement.
Why do concrete joint edges break under forklifts?
Once a joint edge chips, forklift wheels repeatedly strike the unsupported edge. This impact can enlarge the damaged area over time.
How are broken joint shoulders repaired?
A typical repair approach involves removing loose and unsound concrete, preparing a sound boundary, rebuilding the joint edges and preserving the joint’s required function.
What is a pothole in a concrete factory floor?
A pothole is a local area where concrete has broken down and material has been lost. The damaged area can become larger under repeated wheel impact.
Should potholes be repaired before epoxy flooring?
Yes. Loose and unsound concrete should be removed, the area rebuilt and the substrate made suitable before the final epoxy system is installed.
Can I pour epoxy coating directly into a pothole?
A normal final epoxy coating should not be treated as a substitute for a proper deep concrete repair. The damaged substrate needs to be rebuilt first.
How deep can Floorzy Screed Plus be applied?
Floorzy currently publishes Screed Plus at approximately 5–50 mm per layer. Final repair design depends on the actual substrate condition.
Can Screed Plus repair potholes?
Floorzy positions Screed Plus for holes, spalled areas, damaged concrete, depressions and floor levelling in suitable applications. The damaged material still needs proper preparation first.
Can Screed Plus repair moving joints?
Do not assume so. A moving joint needs a detail that respects its intended function. A repair mortar should not automatically be used to lock a functional movement joint.
Can a thin epoxy overlay fix an uneven factory floor?
A thin resin finish should not be expected to correct major level differences. Dedicated repair or levelling should happen first.
What if my floor has a 20 mm depression?
A dedicated levelling or screed system may be required. The repair build should be treated separately from the final wearing-floor thickness.
Can Floorzy repair the concrete and then install epoxy?
Floorzy’s current industrial-flooring approach combines assessment, mechanical preparation, repair, levelling where required and installation of the selected final flooring system.
Why must weak concrete be removed before repair?
A repair can only perform as well as the material it is bonded to. Bonding to loose or friable concrete can leave a weak interface.
Can epoxy make weak concrete strong?
A resin system can protect a suitable prepared surface. It should not be expected to restore the structural capacity of seriously unsound concrete simply by coating it.
Why do potholes come back after repair?
Possible reasons include leaving weak concrete around the repair, incorrect preparation, wrong repair material, continued movement, water, traffic or insufficient cure. The actual cause should be investigated.
Why do crack repairs reopen?
The crack may still be moving, the underlying cause may remain active, the repair may not suit the movement, or the substrate may not have been prepared correctly.
Can forklift traffic make cracks worse?
Forklift traffic can increase mechanical stress at weak floor areas, especially potholes, broken joint edges and previously damaged concrete. The underlying cause of a crack still needs to be identified separately.
Should joint repairs be flush with the floor?
For wheeled industrial traffic, the repaired area should normally create a practical wheel transition consistent with the project detail. Abrupt height differences can create repeated impact.
Should cracks be repaired before surface grinding or after?
The exact sequence depends on the floor and repair method. Mechanical preparation often exposes the true condition of cracks, old patches and weak concrete before final repairs are completed.
Should potholes be repaired before the epoxy primer?
The substrate should normally be brought to the required sound, repaired condition before the final flooring system is built. Follow the approved system sequence.
Can a repaired floor receive heavy forklifts immediately?
No. Repair materials and final flooring have defined cure requirements. Heavy traffic should return only according to the approved project schedule.
What floor damage should an engineer inspect?
Possible warning signs include significant vertical displacement, ongoing settlement, wide structural cracks, cracking around columns or machine foundations, widespread unsound concrete and recurring movement after previous repairs.
What should I send Floorzy for a damaged floor assessment?
Share the project location, approximate area, wide photographs, close-up crack and joint photographs, pothole depth where known, a short video, forklift traffic, machine locations and details of previous repairs.
Don’t Put a New Floor Over an Unresolved Old Problem.
A crack, a joint and a pothole can all look like damaged concrete.
But they are not the same defect.
Classify the damage. Find the cause. Repair the substrate. Preserve movement where movement belongs.
Then install the industrial flooring system.