How do you prepare stucco for painting on an older Ottawa home?

Proper preparation is 80% of a successful stucco paint job — and on older Ottawa homes, there's usually more prep work than painting. Rushing this stage is the single biggest reason stucco paint jobs fail within a few years. Here's the full process that professional painters follow in Ottawa.

Step-by-Step Stucco Prep for Older Ottawa Homes

1. Inspection (30 minutes–1 hour): Walk the entire perimeter and document every issue. On older Ottawa homes, look for hollow-sounding stucco (tap with a knuckle — a hollow sound means the stucco has delaminated from the substrate), cracks wider than a hairline, crumbling or soft spots, efflorescence (white salt deposits), mildew or algae growth (especially on north-facing walls), and any areas where previous paint is peeling or bubbling.

2. Cleaning: Pressure wash the entire surface at 1,500–2,000 PSI maximum — higher pressure damages older stucco. Keep the nozzle at least 12 inches from the surface and use a 25-degree or 40-degree tip. For mildew and algae (common on Ottawa homes shaded by mature trees), pre-treat with a solution of 1 part bleach to 3 parts water, let it sit 15 minutes, then rinse. Professional washing runs $0.25–$0.50 per square foot in Ottawa.

3. Repairs — this is the big one: Hairline cracks get filled with elastomeric caulk ($8–$12 per tube). Cracks wider than 1/8 inch need to be chiselled out to a V-shape, cleaned, and filled with stucco patching compound ($15–$25 per tub). Delaminated sections must be removed entirely and re-stuccoed — if more than 20–25% of the surface is delaminated, a full re-stucco may be more cost-effective than extensive patching.

On pre-1970s Ottawa homes, check for multiple layers of old paint. If there are 4+ layers or extensive peeling, you may need to remove loose paint with a wire brush or scraper. Chemical strippers ($25–$40 per gallon) work on stubborn areas. Homes built before 1960 may have lead paint — test with a $15 kit before disturbing any old coatings. If lead is present, you need a certified lead-safe contractor for removal.

4. Drying time: After washing, allow 48–72 hours of dry weather before priming. Ottawa's humidity in spring and fall means this can stretch to 4–5 days. Don't prime damp stucco — use the plastic sheeting test to confirm dryness.

5. Priming: Apply a masonry primer or alkali-resistant primer to the entire surface. On older stucco with extensive repairs, a block filler primer ($40–$60/gallon) evens out the texture differences between original and patched areas. One coat minimum; two coats on heavily repaired sections. Budget $0.50–$1.00 per square foot for primer.

6. Caulking transitions: Seal all joints where stucco meets windows, doors, trim, and other materials. Use a high-quality polyurethane or hybrid sealant rated for -30°C — cheap caulk hardens and cracks in Ottawa winters.

Total prep cost on an older Ottawa home typically runs $2,000–$5,000 depending on condition, before a drop of finish paint goes on. It's the unsexy part of the job, but it's what separates a 3-year paint job from a 12-year one.

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Looking for experienced contractors? The Ottawa Construction Network connects Ottawa homeowners with qualified professionals:

• 613Bins
• RenoMotion Inc.
• ALTIOR CONSTRUCTION
• Eastern Residential Solution
• Rrenovatios