Waterproofing Masonry Walls and Masonry Waterproofing Paint
Waterproofing Masonry Walls and Masonry Waterproofing Paint
Masonry walls are strong, durable, and used throughout residential, commercial, and industrial construction. Brick, concrete block, cinder block, stone, mortar, and poured concrete can all provide long-lasting structural performance.
However, masonry is not automatically waterproof.
Most masonry materials contain pores that can absorb water. Walls also contain mortar joints, cracks, penetrations, transitions, and other openings that may allow moisture to enter. Once water gets into a masonry wall, it can contribute to stains, efflorescence, mold-friendly conditions, peeling paint, deteriorating mortar, damaged finishes, and corrosion of embedded metal.
Masonry waterproofing is the process of reducing or stopping water from entering these walls. Depending on the structure and exposure, that may involve a penetrating sealer, masonry waterproofing paint, cementitious coating, exterior membrane, joint repair, drainage system, or a combination of methods.
The correct product depends on whether the wall is inside or outside, above or below grade, exposed to rain or groundwater, and made from brick, concrete block, stone, or another material.
Rebotec USA provides mineral-based waterproofing products for concrete and mortar used in residential, commercial, and industrial construction. For help choosing a product for waterproofing masonry, call Rebotec USA at +1 469-352-3379.
What Is Masonry Waterproofing?
Masonry waterproofing is the process of protecting brick, block, concrete, stone, mortar, or other cementitious materials from water intrusion.
A masonry waterproofing system may include:
- Penetrating water repellent
- Masonry waterproofing sealer
- Masonry waterproofing paint
- Cementitious coating
- Mineral-based coating
- Elastomeric coating
- Liquid-applied membrane
- Sheet membrane
- Mortar-joint repair
- Crack sealant
- Flashing
- Drainage board
- Foundation drain
- Integral waterproofing additive
Some methods reduce the amount of water absorbed by the masonry. Others create a continuous barrier over the wall. Drainage systems redirect water so it does not continue building pressure against the structure.
The best solution depends on the cause and severity of the moisture problem.
Why Masonry Walls Absorb Water
Masonry may look solid, but many masonry products contain microscopic pores and capillary pathways.
Water can move into a wall through:
- Brick faces
- Concrete block
- Cinder block
- Mortar joints
- Concrete pores
- Cracks
- Missing mortar
- Pipe penetrations
- Window openings
- Wall caps
- Parapets
- Construction joints
- Wall-to-footing transitions
Water may reach the wall because of:
- Wind-driven rain
- Groundwater
- Wet soil
- Poor grading
- Short downspouts
- Clogged gutters
- Roof leaks
- Failed flashing
- Damaged coping
- Irrigation
- Plumbing leaks
- Condensation
A masonry coating may help protect the wall, but it should not be used to hide a roof, flashing, drainage, or structural problem.
Signs That Masonry Needs Waterproofing
Common signs of moisture movement include:
- Dark patches on the wall
- Water stains
- White powdery deposits
- Peeling paint
- Bubbling coatings
- Damp basement walls
- Musty odors
- Mold or mildew
- Crumbling mortar
- Spalling brick or concrete
- Water around windows
- Wet corners
- Rust stains
- Recurring cracks
- Water after heavy rain
White powder on masonry is often efflorescence. It forms when water travels through the material, carries dissolved salts to the surface, and evaporates.
Efflorescence is not always a structural defect, but it is a sign that moisture is moving through the wall.
Masonry Waterproofing vs Masonry Sealing
Masonry sealing and masonry waterproofing are related, but they do not always provide the same level of protection.
Masonry Sealing
A masonry sealer may:
- Reduce water absorption
- Protect against rain
- Preserve a natural appearance
- Reduce staining
- Limit efflorescence
- Protect porous surfaces
Sealers are often useful on above-grade walls that face weather but not heavy water pressure.
Masonry Waterproofing
A waterproofing system may:
- Resist liquid water
- Handle more severe exposure
- Protect below-grade walls
- Address joints and cracks
- Work with exterior drainage
- Resist water pressure when specifically designed to do so
A basic masonry waterproofing sealer may not stop active groundwater, running leaks, or water entering through open joints.
Types of Masonry Waterproofing Products
Masonry waterproofing products work in different ways. Understanding the main categories can help you choose the right one.
Penetrating Masonry Waterproofing Sealer
A penetrating sealer enters the pores of brick, block, concrete, or mortar.
Rather than creating a thick film, it changes the way the treated surface interacts with water.
Potential benefits include:
- Maintains the natural masonry appearance
- Reduces water absorption
- Does not create a heavy painted finish
- May allow water vapor to escape
- Is less likely to peel than some coatings
- Helps protect against wind-driven rain
Penetrating sealers are commonly used on:
- Brick walls
- Above-grade block walls
- Concrete facades
- Stone masonry
- Chimneys
- Retaining walls
- Exposed foundation walls
- Commercial masonry buildings
They may not stop:
- Active leaks
- Open cracks
- Failed mortar joints
- Groundwater pressure
- Water behind the wall
- Severe below-grade moisture
A penetrating product also cannot properly enter masonry covered by paint or another film-forming coating.
Concrete and Masonry Waterproofing Sealer
A concrete & masonry waterproofing sealer may be designed for several cementitious surfaces, including:
- Poured concrete
- Concrete block
- Cinder block
- Brick
- Mortar
- Stucco
- Some types of stone
Before using a multi-surface product, check its compatibility with the exact wall.
Brick, dense concrete, porous block, and natural stone absorb liquids differently. A product that performs well on one surface may require different preparation or coverage on another.
Masonry Waterproofing Paint
Masonry waterproofing paint creates a visible coating over the wall.
Depending on the product, it may:
- Add color
- Reduce surface absorption
- Fill small pores
- Improve appearance
- Make walls easier to clean
- Help resist rain
- Provide protection against light dampness
- Cover stains and discoloration
Masonry paint products may be:
- Acrylic
- Cementitious
- Mineral based
- Elastomeric
- Rubberized
- Epoxy
- Polyurethane
Not every masonry paint is a true waterproofing product. Standard decorative paint may change the wall's appearance without providing dependable moisture protection.
Masonry Sealer Paint
Masonry sealer paint combines the appearance of paint with some of the protective qualities of a sealer.
It may be useful for:
- Basement walls
- Garages
- Utility rooms
- Concrete block walls
- Above-grade foundations
- Exterior commercial masonry
- Interior concrete walls
The product should be chosen based on:
- Interior or exterior use
- Above- or below-grade location
- Positive- or negative-side water pressure
- Surface moisture
- Existing coatings
- Masonry porosity
- Planned finish
Cementitious Masonry Waterproofing
Cementitious coatings contain cement-based ingredients and selected additives. They are designed to bond to compatible concrete and masonry surfaces.
They may be used on:
- Basement walls
- Foundation walls
- Concrete block
- Brick
- Mortar
- Retaining walls
- Water tanks
- Pools
- Elevator pits
- Utility structures
Potential advantages include:
- Compatibility with cement-based materials
- Ability to fill masonry pores
- Application to some damp surfaces
- Strong bond to properly prepared walls
- Interior and exterior options
- Mineral-based composition
Some cementitious coatings are rigid. Others are polymer modified for greater flexibility.
Rigid coatings may crack if the wall moves. Structural cracks and moving joints require separate treatment.
Mineral-Based Masonry Waterproofing
Mineral-based products are designed to work with concrete, mortar, and other cementitious materials.
Rebotec Paint is a surface-applied mineral-based hydrophobic waterproofing product for compatible concrete and masonry applications.
Rebotec Admix Powder can be mixed into new concrete or mortar to help create hydrophobic properties throughout the material.
These products may be considered for:
- New masonry construction
- Mortar
- Concrete block walls
- Basement walls
- Foundation repairs
- Commercial masonry
- Retaining walls
- Other moisture-exposed cementitious surfaces
The correct product and application method depend on the substrate and water exposure.
Elastomeric Masonry Paint
Elastomeric coatings create a flexible film over exterior masonry.
They may help:
- Resist wind-driven rain
- Bridge very small surface cracks
- Protect rough or textured walls
- Add a uniform color
- Tolerate limited expansion and contraction
Elastomeric coatings are often used on:
- Exterior block walls
- Stucco
- Concrete facades
- Commercial buildings
- Above-grade foundation walls
Not every elastomeric product is suitable for below-grade soil contact or water under pressure.
Masonry Waterproofing Membranes
Membranes create a more continuous water barrier than many basic sealers.
They may be:
- Liquid applied
- Sheet applied
- Self adhered
- Rubberized
- Asphalt based
- Polyurethane based
- Cementitious
- Bentonite based
Membranes are commonly used for:
- Below-grade foundations
- Basement walls
- Retaining walls
- Planters
- Underground structures
- Water-exposed masonry
Seams, corners, penetrations, and transitions must be carefully detailed.
Interior vs Exterior Masonry Waterproofing
The side of the wall being treated affects how the waterproofing product performs.
Exterior Masonry Waterproofing
Exterior waterproofing is installed where rain, soil moisture, or groundwater first reaches the wall.
This positive-side approach may include:
- Penetrating sealer
- Masonry waterproofing paint
- Liquid membrane
- Sheet membrane
- Cementitious coating
- Flashing repair
- Crack and mortar repair
- Drainage board
- Foundation drain
Exterior waterproofing can help prevent water from entering the masonry.
Interior Masonry Waterproofing
Interior waterproofing is applied to the building-facing side of the wall.
It may include:
- Basement and masonry waterproofing paint
- Cementitious coating
- Mineral-based coating
- Crack repair
- Interior drainage
- Sump pump
- Wall drainage panels
- Dehumidification
Interior coatings may help with light dampness, but water may still enter and remain inside the wall.
For basement walls, confirm that the product is designed for negative-side pressure when groundwater may push from behind the coating.
Masonry Waterproofing Paint for Basement Walls
Basement masonry walls face different conditions than above-grade exterior walls.
A basement wall may be exposed to:
- Wet soil
- Groundwater
- Hydrostatic pressure
- Condensation
- Wall-to-floor leaks
- Hollow block cells
- Cracks
- Damaged foundation drains
Basement and masonry waterproofing paint can help protect a properly prepared wall from certain moisture conditions. However, it should not be expected to stop every basement leak.
Paint may be useful for:
- Porous masonry
- Light dampness
- Surface staining
- Efflorescence reduction
- Improved appearance
- Easier cleaning
- Unfinished basement walls
Paint may not be enough for:
- Running water
- Repeated flooding
- Severe water pressure
- Large cracks
- Bowing walls
- Water entering at the floor
- Failed exterior drainage
- Water inside hollow block cells
Best Masonry Waterproofing Paint
The best masonry waterproofing paint is not the same for every project.
Consider:
The Wall Material
Brick, concrete block, cinder block, stone, poured concrete, and stucco have different absorption and surface characteristics.
Interior or Exterior Use
An exterior coating may not be suitable for occupied indoor spaces. An interior paint may not tolerate weather or soil contact.
Above- or Below-Grade Location
Below-grade walls may face groundwater pressure that an ordinary exterior paint cannot handle.
Positive- or Negative-Side Application
Positive-side products are installed where water first reaches the wall. Negative-side products must resist water pushing through the wall from behind.
Existing Paint
Penetrating sealers cannot soak through existing paint. New coatings must also be compatible with old materials.
Surface Condition
Cracks, loose mortar, efflorescence, mold, and peeling coatings should be addressed before painting.
Desired Appearance
Clear sealers preserve the natural masonry look. Paints and coatings add color and create a uniform surface.
Vapor Permeability
Some walls need to release water vapor. A coating that is too impermeable may trap moisture within the wall.
How to Waterproof Masonry Walls
The exact process depends on the product and wall, but most projects involve the following steps.
Step 1: Identify the Moisture Source
Determine whether water comes from:
- Rain
- Groundwater
- Plumbing
- Condensation
- Roof drainage
- Failed flashing
- Poor grading
- Cracks
- Mortar joints
- Window openings
- Pipe penetrations
Applying paint without finding the cause can lead to recurring failure.
Step 2: Inspect the Wall
Look for:
- Cracks
- Loose mortar
- Spalling
- Efflorescence
- Mold
- Peeling paint
- Bowing
- Open joints
- Failed flashing
- Active water
- Structural movement
Serious cracks or movement should be evaluated before waterproofing.
Step 3: Correct Exterior Water Problems
When applicable:
- Clean gutters
- Extend downspouts
- Repair flashing
- Seal window openings
- Correct grading
- Redirect irrigation
- Repair wall caps
- Inspect foundation drainage
Reducing water exposure improves the waterproofing system's performance.
Step 4: Remove Failed Coatings
Remove:
- Peeling paint
- Loose sealer
- Flaking coatings
- Weak mortar
- Unstable repairs
- Loose masonry
A new coating cannot perform properly when installed over a failing layer.
Step 5: Clean the Masonry
Remove:
- Dirt
- Dust
- Oil
- Mold
- Algae
- Efflorescence
- Construction residue
- Soap or cleaning residue
The cleaning method should be appropriate for the masonry. Aggressive pressure washing or harsh chemicals may damage soft brick, mortar, or stone.
Step 6: Repair Cracks and Mortar Joints
Possible repair materials include:
- Repointing mortar
- Cementitious repair mortar
- Hydraulic cement
- Flexible sealant
- Epoxy
- Polyurethane
- Compatible patching materials
The repair should match the type of movement and masonry.
Step 7: Allow the Wall to Meet Moisture Requirements
Some cementitious products are installed on damp masonry. Other paints and sealers require a dry wall.
Follow the selected product's instructions.
Step 8: Apply Primer When Required
Some masonry coatings require a block filler, masonry primer, or specialty bonding primer.
Primer can help:
- Improve adhesion
- Reduce uneven absorption
- Fill porous surfaces
- Create more uniform coverage
Use only a primer compatible with the complete waterproofing system.
Step 9: Apply the Sealer or Paint
Apply at the required:
- Thickness
- Coverage rate
- Number of coats
- Temperature
- Recoat time
- Application method
Rough masonry, mortar lines, and low areas need complete coverage.
Step 10: Allow Proper Curing
Protect the coating from:
- Rain
- Freezing
- Dust
- Contact
- Soil
- Backfilling
- New finishes
- Water pressure
Dry-to-touch time is not always the same as full cure time.
Waterproofing Different Types of Masonry
Brick Walls
Brick walls often leak because of:
- Cracked mortar
- Failed flashing
- Open joints
- Damaged wall caps
- Porous brick
- Wind-driven rain
Brick may be treated with a breathable penetrating sealer, but mortar and flashing defects should be repaired first.
Painting historic or highly porous brick may change how the wall manages moisture. Product selection should be made carefully.
Concrete Block Walls
Concrete block contains pores, mortar joints, and hollow cells.
Below-grade block walls may require:
- Mortar repair
- Parging
- Exterior membrane
- Drainage board
- Foundation drainage
- Interior drainage when needed
A surface paint may not stop water already stored inside the block cells.
Stone Masonry Walls
Stone walls contain many joints and may use softer historic mortars.
Waterproofing stone may require:
- Repointing
- Drainage corrections
- Appropriate breathable sealer
- Cap or flashing repair
- Compatible interior coating
Dense stone and soft mortar may react differently to sealers.
Poured Concrete Walls
Concrete may absorb water through pores, cracks, construction joints, tie holes, and penetrations.
Concrete waterproofing may include:
- Penetrating sealer
- Cementitious coating
- Mineral-based coating
- Exterior membrane
- Integral admixture
- Crack injection
Exterior Masonry Waterproofing
Above-grade exterior masonry is commonly exposed to wind-driven rain and weather.
A complete exterior approach may involve:
- Mortar repair
- Crack sealing
- Flashing repair
- Coping or wall-cap repair
- Penetrating sealer
- Elastomeric coating
- Mineral-based paint
- Drainage corrections
For below-grade walls, exterior masonry waterproofing may require:
- Excavation
- Wall cleaning
- Crack and mortar repair
- Parging where needed
- Waterproofing membrane
- Protection board
- Drainage board
- Foundation drain
- Proper backfill
- Final grading
Below-grade systems should be designed for soil contact and the expected water pressure.
When Masonry Waterproofing Paint Is Not Enough
A wall coating may not solve the problem when there is:
- Active flowing water
- High groundwater
- Severe hydrostatic pressure
- Bowing walls
- Structural cracks
- Failed flashing
- Roof leaks
- Water entering from the top of the wall
- Damaged foundation drainage
- Water beneath the floor slab
- Repeated basement flooding
- Sewer or plumbing problems
Additional solutions may include:
- Exterior membrane
- Interior perimeter drain
- Sump pump
- Crack injection
- Repointing
- Structural repair
- Foundation-drain replacement
- Flashing replacement
- Roof or coping repair
The water source should guide the repair.
Masonry Waterproofing Contractors
Masonry waterproofing contractors may specialize in different areas.
Some focus on:
- Foundation waterproofing
- Basement drainage
- Brick restoration
- Repointing
- Exterior coatings
- Concrete repair
- Commercial building envelopes
- Structural foundation repair
Before hiring a contractor, ask:
- What is causing the moisture?
- Is the proposed solution interior or exterior?
- Is the product a sealer, dampproofing layer, or waterproof membrane?
- Will cracks and mortar joints be repaired first?
- Is drainage included?
- Is the product rated for the wall and exposure?
- How will penetrations and transitions be treated?
- What preparation is included?
- How will the system be protected?
- Is there a written scope and warranty?
A contractor should explain why the recommended method matches the actual water problem.
Common Masonry Waterproofing Mistakes
Avoid these common mistakes:
- Painting over active leaks
- Ignoring mortar deterioration
- Coating over efflorescence
- Applying sealer to dirty masonry
- Using an interior product outdoors
- Using an above-grade product below ground
- Applying penetrating sealer over paint
- Failing to repair flashing
- Ignoring roof and wall-cap leaks
- Applying liquid coatings too thin
- Missing mortar joints and low spots
- Covering structural cracks
- Ignoring foundation drainage
- Backfilling without membrane protection
- Assuming every masonry paint is waterproof
A waterproofing system is only as strong as its weakest joint, seam, crack, or opening.
How Long Does Masonry Waterproofing Last?
Service life depends on:
- Product type
- Surface preparation
- Masonry condition
- Installation quality
- Weather exposure
- Groundwater
- Structural movement
- Drainage
- Coating thickness
- Maintenance
Exterior walls should be periodically inspected for cracks, open joints, peeling coatings, and failed sealant.
Maintenance of gutters, downspouts, flashing, drainage, and grading can also extend the performance of the waterproofing system.
Get Help Choosing a Masonry Waterproofing Product
Choosing among penetrating sealers, masonry waterproofing paint, cementitious coatings, mineral-based products, elastomeric coatings, and exterior membranes can be difficult.
Rebotec USA helps contractors, builders, distributors, engineers, and property owners evaluate mineral-based waterproofing products for concrete and mortar.
Call Rebotec USA at +1 469-352-3379 for product information, application guidance, and help choosing a waterproofing approach for concrete, concrete block, mortar, basement walls, foundations, or other masonry surfaces.
Conclusion
Masonry waterproofing helps protect brick, concrete block, cinder block, concrete, mortar, stone, and other masonry materials from water intrusion and moisture-related damage.
Penetrating sealers reduce water absorption while preserving the natural appearance of the wall. Masonry waterproofing paint creates a visible protective coating and can improve the wall's appearance. Cementitious and mineral-based products bond with compatible masonry, while elastomeric coatings provide flexible surface protection for appropriate applications.
The best masonry waterproofing paint depends on the wall material, location, water pressure, existing coatings, and desired finish.
Before applying any product, determine where the water comes from. Repair cracks, damaged mortar, flashing, penetrations, drainage, and structural problems first. Clean and prepare the wall according to the product's requirements.
For basement or below-grade walls, paint alone may not be enough. Groundwater, hydrostatic pressure, water-filled block cells, or wall-to-floor leaks may require an exterior membrane, drainage system, sump pump, or more complete waterproofing plan.
For help selecting a mineral-based waterproofing product for concrete or mortar, call Rebotec USA at +1 469-352-3379.
FAQs About Masonry Waterproofing
What is masonry waterproofing?
Masonry waterproofing is the process of protecting brick, block, concrete, stone, mortar, and related materials from water intrusion using sealers, coatings, membranes, repairs, and drainage.
What is the best way to waterproof masonry walls?
The best method depends on the wall material, water source, location, and pressure. Options include penetrating sealers, cementitious coatings, waterproof paint, exterior membranes, mortar repair, and drainage.
What is a masonry waterproofing sealer?
It is a product that penetrates or coats masonry to reduce water absorption and protect the surface.
Does masonry sealer make a wall completely waterproof?
Not always. A sealer may reduce absorption but may not stop active leaks, open cracks, failed joints, or hydrostatic pressure.
What is masonry waterproofing paint?
It is a colored coating designed to protect compatible masonry surfaces from moisture while creating a finished appearance.
What is masonry sealer paint?
Masonry sealer paint combines decorative coverage with some water-resistant or waterproofing properties, depending on the product.
What is the best masonry waterproofing paint?
The best product is one designed for the specific masonry, interior or exterior location, water pressure, surface condition, and desired appearance.
Can masonry waterproofing paint be used in a basement?
Yes, when it is approved for below-grade interior masonry and the expected direction of water pressure.
Can waterproof paint stop a basement leak?
It may help with light dampness, but active leaks, groundwater pressure, cracks, and wall-to-floor water may require repair or drainage.
Can masonry paint be applied over old paint?
Only if the old coating is sound, clean, and compatible. Peeling or failing paint should be removed.
Can penetrating masonry sealer be applied over paint?
Usually not. Existing paint blocks the sealer from entering the masonry pores.
Is concrete and masonry waterproofing sealer suitable for brick?
Some products are, but compatibility should be confirmed. Different brick and stone materials can respond differently to sealers.
Does masonry waterproofing prevent efflorescence?
It may reduce moisture movement that causes efflorescence, but existing deposits and the underlying water source must also be addressed.
Can concrete block walls be waterproofed?
Yes. Block walls may be protected with sealers, coatings, exterior membranes, mortar repairs, drainage board, and foundation drainage.
Can exterior masonry be waterproofed without painting it?
Yes. A clear penetrating water repellent may reduce absorption while preserving the wall's natural appearance.
Are elastomeric coatings good for masonry?
They can be useful on compatible above-grade walls because they tolerate limited movement and help resist rain. Not all are approved below grade.
Do masonry walls need to breathe?
Many masonry assemblies benefit from some vapor movement. Product selection should consider whether trapping moisture could damage the wall.
Should cracks be repaired before masonry waterproofing?
Yes. Cracks, failed mortar joints, and penetrations should be evaluated and repaired with compatible materials before the coating is installed.
When should I hire masonry waterproofing contractors?
Professional help is recommended for structural cracks, repeated leaks, high groundwater, deep excavation, commercial walls, failed flashing, or widespread masonry deterioration.
How do I compare masonry waterproofing contractors?
Compare the diagnosis, preparation process, product ratings, drainage plan, crack and joint details, scope of work, and warranty-not only the price.
Can integral waterproofing be used in masonry construction?
Yes. Compatible integral additives may be mixed into new mortar, grout, concrete, or repair materials to improve water resistance throughout the material.
Who can help me choose masonry waterproofing products?
Rebotec USA can help you evaluate mineral-based waterproofing products for concrete and mortar. Call +1 469-352-3379 for product and application guidance.
