Understanding Brick Wall Types
1. Brick Veneer Construction
Brick veneer walls serve as decorative cladding attached to the building frame with metal ties, leaving a 1-inch air gap behind the brick.
Key Features:
- Steel lintels support bricks over openings.
- Weep holes at the base allow moisture drainage.
- No header bricks are visible, since veneer is non-structural.
- Bearing ledges or steel angles at the foundation provide support.
2. Solid Masonry Construction
Solid brick walls (also called double-wythe systems) are structural and self-supporting.
Characteristics:
- Built from two layers of brick connected with header bricks or metal ties.
- Arched openings instead of steel lintels often indicate true solid masonry.
- Inspectors should check for bulging or displacement, which may signal tie or mortar failure.
3. Causes and Patterns of Cracking
Cracks appear when stresses exceed the material’s capacity. Properly interpreting their shape and location reveals the underlying cause.
3.1 Differential Soil Movement
Foundation shifts can result from:
- Heaving: Expansion of wet or frozen soil.
- Expansive clay soils: Swelling and shrinking with moisture changes.
- Settlement: Poorly compacted fill or loss of soil moisture.
- Collapsible soils: Loss of strength when wet.
- Soil creep: Gradual downhill movement.
3.2 Craze Cracking
Random hairline cracks on glazed bricks typically result from manufacturing flaws or freeze–thaw cycles.
Crack closures indicate movement direction:
- Wider at top → Settlement near corners.
- Wider at bottom → Heave or mid-wall settlement.
4. Spalling: Surface Break-Off in Brick
Spalling occurs when rigid, high-cement mortar prevents bricks from expanding as absorbed water freezes.
- Soft, lime-based mortar flexes and relieves stress.
- Hard Portland cement mortar does not, causing the brick face to pop off.
- Proper repointing with compatible mortar prevents further surface loss.
5. Moisture and Staining Issues
5.1 Efflorescence
White crystalline deposits indicate moisture migration through masonry. Although usually cosmetic, they warn of possible water infiltration.
5.2 Subflorescence
Salt crystals forming beneath the surface generate hydrostatic pressures (up to 5,000 psi), exceeding brick compressive strength and causing spalling.
Identify and control the moisture source to prevent recurrence.
5.3 Other Stains and Erosion
- Rust, smoke, or mortar residues are usually cosmetic.
- Sandblasting should never be used, as it erodes the brick surface.
6. Mortar Joint and Sill Inspection
- Mortar deterioration: Caused by weathering and freeze–thaw cycles; repointing restores integrity.
- Brick sills: Must slope at least 15° to shed water. Flat or concave sills trap moisture and deteriorate prematurely.
7. Summary for Inspectors
When inspecting brick exteriors, always check for:
✓ Type of wall (veneer vs. solid masonry)
✓ Cracking pattern and closure direction
✓ Signs of spalling or efflorescence
✓ Mortar condition and weep holes
✓ Proper sill slope and drainage
Conclusion
A clear understanding of how bricks behave under stress, moisture, and temperature changes allows inspectors to distinguish between cosmetic wear and structural failure — ensuring more accurate and professional inspections.
