Brick piers are a common feature in many homes, supporting porches, decks, and structural loads. Without proper waterproofing, these masonry elements can absorb moisture leading to freeze-thaw damage, efflorescence, and structural deterioration. This guide covers the causes of moisture damage in brick piers and the most effective waterproofing strategies.
How Brick Piers Absorb Water
Brick is a porous material that naturally absorbs water through capillary action. A brick pier can absorb water from several sources: rain hitting the exposed surface, groundwater wicking up from the foundation, splashback from rain hitting the ground, and snow accumulation at the base. Water entering the brick expands when it freezes, causing spalling (surface flaking) and cracking.
Water Absorption Rates by Brick Type
| Brick Type | Water Absorption (24 hr) | Porosity | Freeze-Thaw Resistance | Best Application |
|---|---|---|---|---|
| SW (Severe Weathering) grade | Less than 8% | Low | Excellent | Exterior piers, foundations |
| MW (Moderate Weathering) grade | 8-17% | Moderate | Good | Exterior above grade |
| NW (No Weathering) grade | Over 17% | High | Poor | Interior only |
| Engineering brick (Class A) | Less than 4.5% | Very Low | Excellent | Piers, retaining walls, below grade |
Waterproofing Methods for Brick Piers
Method 1: Penetrating Water Repellents
These clear, breathable sealers penetrate the brick surface and line the pores with a water-repellent coating. They allow water vapor to escape while preventing liquid water from entering. Silane/siloxane-based products are the industry standard, lasting 5-10 years before reapplication is needed. Apply at $0.50-1.00 per sq ft.
Method 2: Masonry Waterproofing Paint
Thicker than penetrating sealers, these paints form a protective film on the brick surface. They are effective but can trap moisture within the brick if not properly formulated. Cement-based waterproof paints are preferred over acrylic for breathability. Cost: $0.30-0.80 per sq ft. Lifespan: 3-5 years.
Method 3: Physical Waterproofing (Capillary Break)
For new construction, a physical moisture barrier can be installed between the pier and its foundation:
| Capillary Break Material | Effectiveness | Installation Difficulty | Cost per sq ft |
|---|---|---|---|
| Sheet metal flashing (copper or stainless steel) | Excellent | Moderate | $3-6 |
| Self-adhering membrane (peel-and-stick) | Excellent | Easy | $2-4 |
| Bituminous coating | Good | Easy | $1-2 |
| Polyethylene sheet (6 mil) | Moderate | Easy | $0.30-0.50 |
Step-by-Step Waterproofing Process
Phase 1: Surface Preparation
- Clean the pier thoroughly using a masonry cleaner or pressure washer (low pressure, wide fan tip)
- Remove any existing paint, efflorescence, or loose mortar
- Repoint any cracked or missing mortar joints
- Allow the pier to dry completely (minimum 48-72 hours of dry weather)
Phase 2: Application
- Apply penetrating sealer according to manufacturer instructions (typically 2 coats)
- Use a low-pressure sprayer or roller for even coverage
- Ensure complete saturation of the brick surface
- Pay special attention to the top of the pier (the most vulnerable surface)
- Install a pier cap or flashing at the top to shed water
Phase 3: Pier Cap Installation
A pier cap is one of the most important waterproofing elements. It protects the top of the pier where water would otherwise pool and penetrate through the exposed brick cores:
| Cap Material | Cost | Lifespan | Aesthetic |
|---|---|---|---|
| Precast concrete cap | $20-50 | 20-30 years | Matches most masonry |
| Stone cap (limestone, granite) | $50-150 | 50+ years | Premium appearance |
| Cast stone cap | $30-80 | 25-40 years | Good match to natural stone |
| Metal cap (copper, lead-coated copper) | $40-100 | 50+ years | Distinctive appearance |
Signs of Water Damage in Brick Piers
- Efflorescence: White, powdery deposits on the surface (water-soluble salts brought to the surface by evaporating water)
- Spalling: Surface flaking or chipping of the brick face
- Mortar deterioration: Soft, crumbly, or missing mortar in joints
- Damp patches: Dark areas that remain wet long after rain
- Moss or algae growth: Biological growth on damp surfaces
- Interior moisture: Dampness on interior walls adjacent to the pier
Maintenance Schedule
| Frequency | Task |
|---|---|
| Annually | Inspect for cracks, spalling, or efflorescence |
| Every 2 years | Check and repair mortar joints (tuckpointing as needed) |
| Every 5-7 years | Reapply penetrating water repellent |
| After major storms | Inspect for damage from wind-driven rain |
Conclusion
Waterproofing brick piers is essential for their long-term structural integrity. The most effective approach combines a penetrating water repellent on the brick surface with a properly installed cap at the top of the pier and a capillary break at the base. Regular inspection and maintenance will extend the life of brick piers indefinitely. For more on masonry construction, explore our guide on masonry construction principles.