Published: December 08, 2025

Brick foundations are strong and long-lasting, but they are also highly porous. Over time, moisture can easily penetrate brick and mortar joints, leading to damp basements, structural deterioration, and expensive long-term damage. If you’ve noticed wet bricks, crumbling mortar, or moisture inside your basement, it’s important to act quickly.

At Direct Waterproofing, we help homeowners diagnose and repair moisture issues in brick foundations before they turn into structural problems. Here’s what you should do if your brick foundation is absorbing water.

Why Brick Foundations Absorb Water

Brick and mortar are made of natural materials that contain countless tiny pores. When exposed to constant moisture, the foundation begins to absorb water through:

• Capillary action
• Surface saturation
• Damaged or missing mortar
• Cracks in the brick face
• Poor drainage around the home
  

Because brick is more absorbent than poured concrete, moisture problems tend to appear faster and spread more widely.

Signs Your Brick Foundation Is Absorbing Water

Watch for these warning indicators:

• Dark, damp patches on the exterior brick
• Efflorescence (white, powdery residue)
• Crumbling mortar (known as mortar deterioration or “spalling”)
• Peeling paint on interior basement walls
• Higher humidity or musty odors
• Mold or mildew growth
• Water stains on basement floors
• Cracked or bulging bricks
  

If you spot any of these issues, moisture has already begun penetrating the brick—and immediate action is recommended.

Step 1: Identify the Source of Moisture

Before any repairs can be made, you need to know where the water is coming from. Common sources include:

1. Poor Grading

If the soil slopes toward the house instead of away, water collects at the foundation.

2. Faulty or Missing Downspout Extensions

Downspouts that release water near the wall cause excessive saturation.

3. Cracked or Damaged Brick

Even small cracks allow water into the wall system.

4. Deteriorated Mortar

Mortar breaks down over time, creating gaps where water enters and travels.

5. Hydrostatic Pressure

High groundwater levels push water through the foundation walls.

A professional foundation inspection will determine the cause and identify the proper repair method.

Step 2: Repair and Repoint Deteriorated Mortar

One of the most important steps is repointing—a process where old, crumbling mortar is removed and replaced with new, properly mixed mortar.

Why repointing matters

• Restores structural strength
• Seals moisture pathways
• Prevents further deterioration of the brick
  

Using the right mortar mixture is essential, especially for older homes, as overly strong modern mortar can crack the brick.

Step 3: Fix Cracks and Exterior Damage

Any damaged bricks should be repaired or replaced. Cracks in the brick face allow water to penetrate deep into the wall.

Repairs typically include:

• Filling small cracks with masonry sealants
• Replacing spalled or severely damaged bricks
• Sealing larger cracks with appropriate masonry techniques
  

This prevents future water entry and keeps the foundation stable.

Step 4: Improve Drainage Around the Home

Brick foundations are far more vulnerable to constant moisture exposure than concrete ones, making drainage improvements especially important.

Recommended drainage upgrades:

• Regrading soil to slope away from the house
• Extending downspouts 6–10 feet from the foundation
• Cleaning gutters regularly
• Installing or repairing French drains or weeping tile systems
• Adding a sump pump if groundwater levels are high
  

Directing water away from the foundation is the most effective long-term solution.

Step 5: Apply a Breathable Masonry Sealer (Not Paint)

Here’s what most homeowners get wrong:

You should NOT use standard paint or non-breathable sealers on brick foundations.

These products trap moisture inside the wall, which leads to:

• Accelerated brick decay
• Mold growth
• Freeze–thaw damage
• Spalling and structural weakening
  

Instead, use a vapor-permeable masonry sealer specifically designed for brick. These sealers stop water from entering while still allowing trapped moisture to escape.

Step 6: Waterproof the Interior or Exterior (If Needed)

If water continues to infiltrate your basement, a professional waterproofing system may be necessary.

Exterior Waterproofing

• Excavation around the foundation
• Application of a waterproof membrane
• Drainage board installation
• New weeping tile system

Best for severe moisture or structural issues.

Interior Waterproofing

• Interior drainage system
• Waterproof membrane on interior walls
• Sump pump installation
  

Ideal when exterior excavation is not possible.

Direct Waterproofing can help determine which method suits your foundation condition and property layout.

Step 7: Address Humidity and Ventilation Inside the Basement

Even after fixing external issues, interior humidity must be controlled.

Simple steps:

• Install a dehumidifier
• Improve airflow
• Remove wet drywall or insulation
• Use vapor-permeable finishing materials
  

This helps keep the basement dry long-term.

When to Call a Professional

If your brick foundation is showing:

• Severe mortar deterioration
• Constant dampness
• Cracked or bulging brick
• Repeated efflorescence
• Water entering after heavy rain
  

You should contact a waterproofing professional immediately. Brick foundation issues worsen quickly, especially in Toronto’s freeze–thaw climate.

Final Thoughts

Brick foundations are durable, but they are also highly vulnerable to water absorption. Early intervention is the key to preventing structural damage, mold growth, and expensive repairs. By addressing drainage, repairing mortar, sealing the brick properly, and installing waterproofing systems where needed, you can restore and protect your foundation.

At Direct Waterproofing, we specialize in diagnosing brick foundation problems and providing long-lasting, effective solutions.