What Is Underground Moisture?
Underground moisture refers to the natural presence of water vapor or liquid water that exists below ground level. This moisture can come from several sources — groundwater, capillary rise from the soil, leakage from nearby plumbing systems, or even condensation due to temperature changes. While it might not be visible, this hidden moisture can have a serious impact on any type of flooring system, especially in basements, ground floors, or car park decks.
How Underground Moisture Affects Floor Surfaces
When moisture migrates upward through concrete or subfloor layers, it often brings dissolved salts and minerals with it. Over time, this causes several visible and structural problems on the floor surface:

1. Blistering and Peeling of Coatings
   Excess moisture trapped under resin or epoxy coatings causes pressure buildup, leading to bubbles, blisters, and delamination.
2. Cracking and Weakening of Concrete
   Continuous moisture movement softens the cement matrix and promotes microcracks, weakening the floor’s integrity.
3. Efflorescence and Staining
   Moisture carrying salts to the surface results in white crystalline deposits (efflorescence), which make floors look dull and poorly maintained.
4. Mold Growth and Hygiene Concerns
   Damp flooring encourages fungal and bacterial growth, which not only damages the surface but can also create unpleasant odors and health hazards.
5. Adhesion Failure in Flooring Systems
   For areas using vinyl, tiles, or epoxy coatings, moisture prevents proper bonding, causing detachment or hollow-sounding floors over time.

Why Mortar Screed Is the Perfect Solution
A mortar screed acts as a strong, moisture-resistant intermediary layer between the base concrete and the final floor finish. When properly designed and installed, it effectively minimizes the impact of underground moisture and creates a durable, level substrate for coatings or tiles.
Here’s how mortar screed solves the problem:

1. Acts as a Moisture Barrier
   Mortar screed made with polymer-modified or waterproofing additives creates a dense structure that resists moisture penetration from below.
2. Improves Surface Strength and Flatness
   It forms a tough, uniform surface that distributes loads evenly and prevents cracking or delamination of the top coating.
3. Enhances Bonding for Floor Finishes
   A well-prepared mortar screed provides excellent adhesion for subsequent finishes such as epoxy, PU coating, tiles, or vinyl — even in areas with high humidity.
4. Reduces Efflorescence and Damp Patches
   By controlling moisture migration, mortar screed minimizes salt deposits and surface dampness, maintaining a clean, aesthetic look.
5. Extends the Floor’s Lifespan
   With controlled moisture movement, the entire flooring system remains stable, reducing the need for frequent repairs or recoating.

Additional Advantages of Using Mortar Screed
Beyond moisture protection, mortar screed brings several practical benefits:

• High Load Resistance – Ideal for industrial, commercial, and car park floors where heavy traffic and machinery are common.
• Customizable Thickness – Can be applied in varying thicknesses to correct uneven floors and achieve the desired height tolerance.
• Compatibility with Various Coatings – Works perfectly under epoxy, PU, and cementitious coatings, ensuring strong long-term performance.
• Fast Application and Curing Options – Specialized screed formulations allow faster drying and early installation of top coatings.

Conclusion
Underground moisture is one of the most common and underestimated threats to floor performance. Left unaddressed, it leads to coating failures, cracks, and costly repairs. A properly applied mortar screed system not only provides a robust moisture barrier but also improves strength, surface smoothness, and coating durability.
For car parks, industrial floors, or any ground-level installation, using mortar screed is the smart choice to ensure long-term protection, superior performance, and peace of mind.