Parging Damage Types and Severity
Not all parging damage is the same. Knowing the type and severity helps you decide between a quick patch and a professional repair.
| Damage Type | What It Looks Like | Severity | Action |
|---|---|---|---|
| Hairline Cracks | Fine surface cracks, typically <0.5mm wide | Low | Monitor or seal; no repair needed if narrow |
| Structural Cracks | >2–3mm wide, may run through depth | High | Remove section, assess substrate, and repair |
| Delamination | Parge separating from substrate (hollow sound) | High | Remove all loose parge; re-parge after prep |
| Spalling | Flakes or chunks breaking away | Medium | Seal small spalls; remove and repair if extensive |
| Efflorescence | White salt staining, crusting on surface | Medium | Address moisture source; clean surface; reseal |
| Active Water Leakage | Water flowing or staining through parging | High | Diagnose moisture path; repair substrate; re-parge |
How to Inspect Your Parging
Do a thorough visual and tactile inspection at least once per year:
1. Look for cracks and spalling
Walk around the entire foundation. Note hairline cracks, wider splits (>2mm), flaking, or peeling.
2. Tap test for delamination
Tap the surface gently with a hammer handle. Solid parge sounds dense; delaminated areas sound hollow.
3. Check for efflorescence
White salt staining or crusts indicate moisture migration. Note the location and extent.
4. Look for active water
Wet areas, staining, or water seepage are red flags. Mark them and investigate the source.
5. Check grade and drainage
Soil touching the parge promotes moisture. Clear soil back 6+ inches. Check downspouts direct water away.
Root Causes of Parging Failure
Understanding why parging failed helps you avoid the same problem after repair:
Poor Surface Preparation
If the original substrate wasn't cleaned, dampened, and primed properly, the new parge won't bond. This is the #1 cause of early failure.
Incompatible Materials
Mixing parging types (e.g., applying modern polymer mix over old lime mortar without a bonding agent) causes delamination.
Freeze-Thaw Damage
Water trapped in the parge or behind it expands during freeze, creating cracks and spalling. Common in Ontario winters.
Over-Thick Coats
Single heavy lifts dry unevenly and crack. Multiple thin coats (scratch + finish) are stronger and longer-lasting.
Bad Weather During Cure
Rain, freezing, or rapid drying during cure causes weak parging. Pro application includes weather protection.
Underlying Moisture Issues
If water enters from the inside or groundwater is present, parging will fail repeatedly. The real problem must be fixed first.
Repair vs. Replacement Decision Tree
Use this framework to decide whether spot repair or full re-parging is the right choice:
Choose SPOT REPAIR if:
- Damage is localized (under 100 sq ft total)
- Surrounding parge is sound and well-adhered
- No active moisture problems
- Substrate underneath is not compromised
Choose FULL RE-PARGING if:
- Damage is widespread (>100 sq ft or >20% of wall)
- Large sections are delaminated or hollow-sounding
- Active moisture, efflorescence, or water leakage present
- Parging is 15+ years old and failing across multiple elevations
DIY Parging Repair: Small Patches
For experienced DIYers, small patches (50 sq ft or less) can be tackled. Here's the process:
Use a cold chisel and hammer to carefully remove all loose, delaminated, or cracked parge. Go to sound substrate. Be thorough—any hidden loose parge will fail again.
Brush out dust, salts, and debris. If the substrate is porous concrete block, use a wire brush to roughen the surface for better bonding.
Spray the area with water until damp. Avoid standing water, which weakens bonding. Damping prevents rapid suction of water from the new parge.
Use a primer/bonding agent recommended by your parging product manufacturer. This bridges old and new material and ensures adhesion.
Mix parge per product instructions (thick, peanut-butter consistency). Apply in thin lifts (max 1/4"—check product limit). Use a trowel and feather edges to blend.
Protect from rain (cover if needed) and freezing during cure (typically 7–14 days per product). Keep weather conditions moderate during cure.
Pro tip: If the substrate is concrete, ensure any cracks or voids deeper than 1/4" are filled first. Otherwise, the parging will bridge and crack.
When to Call a Professional
Get professional help if any of these apply:
Widespread damage (>100 sq ft or visible across multiple walls)
Below-grade parging (foundation walls below soil line)
Active moisture or water leakage (diagnosis and remediation needed)
Multi-story buildings (scaffolding and height require experience)
Previously failed repairs (underlying issue not addressed before)
Heritage or special masonry (requires compatible materials and expertise)
Prevention & Ongoing Maintenance
Once repaired, keep your parging in good condition:
Annual Inspection
Check after hard winters and during spring for new cracks, spalling, or efflorescence.
Seal Small Chips Promptly
A small chip sealed early prevents water penetration and larger failure. Use flexible sealant or spot mortar.
Clear Grade and Mulch
Keep soil and mulch at least 6 inches below the parge. Direct contact traps moisture.
Maintain Drainage
Ensure downspouts direct water away (6+ feet minimum). Manage grading to shed water from the foundation.
Spring Rinse-Down
After winter, rinse salt and residue off the parging to reduce efflorescence and extend life.
We'll inspect your parging, identify root causes, and recommend the best repair strategy— spot patch or full re-parge.
Book a free assessmentFrequently Asked Questions
Can I patch parging myself?
Small patches (under 50 square feet) may be DIY if the substrate is sound. Clean to bare masonry, dampen, apply a bonding agent, and use a quality parging mix in thin lifts. For larger areas or active moisture, hire a pro.
Why is my parging cracking so fast?
Rapid failure usually stems from poor prep, incompatible mixes, application in bad weather, lack of cure protection, or underlying moisture pushing from inside. Address the root cause before re-parging.
Do I need to remove all failing parging?
Yes. Any loose, delaminated, or hollow-sounding parge must go—it will continue to fail and trap moisture. Remove to sound substrate before reapplying.
What is "spalling" parging?
Spalling is when small flakes or chunks break away from the surface due to freeze-thaw, salt damage, or impact. Light spalling can be sealed; widespread spalling calls for repair or re-parging.
How do I know if parging has failed underneath?
Tap the surface with a hammer handle. Solid parge sounds dense; hollow areas sound hollow (delaminated). If more than 10–20% is hollow, removal and re-parging is the safer choice.
Get your parging fixed right the first time
Professional assessment with clear repair recommendations.