What Is the Best Way to Paint Exterior Brick on a Century Home in Ottawa?

Painting exterior brick on a century home in Ottawa is a significant decision — and one that's essentially permanent. Once brick is painted, you're committed to maintaining that paint for the life of the home. Let me walk you through how to do it right, the Ottawa-specific challenges, and the honest costs involved.

Should You Paint the Brick at All?

Before we get into the how, consider the should. Ottawa has many century homes — particularly in Sandy Hill, Lowertown, Centretown, the Glebe, and Old Ottawa South — with original unpainted brick that is part of the neighbourhood's architectural character.

Reasons to paint:

• Severely deteriorated mortar and spalling brick that's been patched with mismatched materials


• Previous lime wash or paint that's failing and needs a uniform finish


• Efflorescence (white salt deposits) that keeps returning despite cleaning


• Personal aesthetic preference for a painted look

Reasons not to paint:

• Your brick is in good condition with sound mortar


• Your home is in a heritage conservation district (check with the City of Ottawa's heritage planning department — painting may require approval or be discouraged)


• You don't want to commit to repainting every 10-15 years


• Original unpainted brick with properly maintained mortar is lower-maintenance than painted brick

If you're in a heritage area, painting original brick can affect your property's heritage status and potentially your neighbours' property values. Check before you commit.

Step 1: Masonry Assessment and Repair ($500-$3,000)

Century-old Ottawa brick has endured 100+ years of freeze-thaw cycles — that's conservatively 15,000 freeze-thaw transitions. The mortar and brick need careful assessment:

Mortar joints:

• Century homes typically have lime mortar, which is softer and more flexible than modern Portland cement mortar. This is intentional — lime mortar absorbs movement and moisture, protecting the brick.


• Repoint failing joints with lime mortar, not Portland cement. Portland cement is too hard for old soft brick and will cause the brick faces to spall (pop off) as moisture is forced through the brick instead of the joints.


• Professional tuckpointing with lime mortar costs $15-$35 per square foot in Ottawa. For a full-house repoint, budget $5,000-$15,000, but most century homes need only partial repointing.

Brick condition:

• Look for spalling (brick faces flaking off), crumbling, or soft spots.


• Individual damaged bricks can be replaced with salvaged period-appropriate brick. Ottawa has suppliers who stock reclaimed century brick for $3-$8 per brick plus installation.


• Do not paint over severely spalled brick — paint won't stop the deterioration, and moisture behind the paint will accelerate it.

Critical point: All masonry repairs must be completed and fully cured (minimum 28 days for new mortar) before painting.

Step 2: Cleaning ($300-$800 professional)

Century brick accumulates a lot of surface contamination that will prevent paint adhesion:

• Efflorescence: White crystalline salt deposits. Brush off dry with a stiff brush. If recurring, the underlying moisture source must be addressed first.
• Dirt and biological growth: Decades of soot, moss, algae, and lichen. Clean with a masonry cleaner and low-pressure wash (800-1,200 PSI maximum). High pressure damages old mortar.
• Old paint or lime wash remnants: Scrape or wire-brush loose material. If the previous coating is well-adhered, you can paint over it after cleaning.

Allow 3-7 days drying time after washing. Use a moisture meter — brick should read below 12% moisture content before painting. Ottawa's humidity can make this a multi-day wait.

Step 3: Choosing the Right Paint System

This is where Ottawa's climate makes the decision for you. Century brick needs a paint system that is breathable — it must allow moisture vapour to pass through from inside the wall to outside. Trapping moisture inside old brick walls causes catastrophic damage in Ottawa's freeze-thaw environment.

The Right Choice: Mineral/Silicate Paint

Mineral silicate paint (like Keim Granital or Romabio Masonry Flat) chemically bonds to the mineral substrate of brick and mortar. It's:

• Fully breathable — vapour-permeable, won't trap moisture
• Extremely durable — 15-25 year lifespan on masonry
• UV and freeze-thaw resistant
• Does not peel or flake — because it bonds chemically, not just mechanically
• $80-$120 per gallon — expensive but the lifespan justifies it

This is what conservation professionals use on heritage masonry across Europe and increasingly in Ottawa.

The Acceptable Choice: Elastomeric Masonry Paint

Elastomeric paint creates a thick, flexible membrane that bridges hairline cracks and resists water penetration:

• Good moisture resistance from the outside
• Stretches with thermal movement — important for Ottawa's -30C to +35C range
• 10-15 year lifespan on masonry
• $50-$70 per gallon
• Must use a breathable formulation specifically rated for masonry

What to Avoid

• Standard acrylic latex house paint: Not designed for masonry porosity. On century brick, it can trap moisture and cause spalling within 2-3 Ottawa winters.
• Non-breathable elastomeric coatings: Some elastomerics are designed for modern concrete, not old brick. Check that the product is vapour-permeable.
• Epoxy or urethane coatings: Completely seal the brick. Will cause severe moisture damage in Ottawa's climate.

Step 4: Priming

On century brick, primer serves two purposes — adhesion and alkali resistance:

• Use a masonry-specific primer rated for alkaline surfaces. Fresh mortar (from repointing) is highly alkaline and will attack standard primers.
• Zinsser Watertite ($35-$45/gallon) or manufacturer-specific masonry primers work well.
• Apply one coat and allow to dry 24 hours.

Step 5: Application

• Apply two coats using a long-nap roller (3/4" to 1-1/4" nap) that gets into brick texture and mortar joints. Back-brush to ensure full coverage of recessed mortar joints.
• Do not spray unless you have excellent masking skills — overspray on windows, trim, and neighbouring surfaces is difficult to remove from masonry.
• Timing: Paint in June through September when Ottawa temperatures are reliably between 10-30C and overnight lows stay above 10C. Masonry holds temperature longer than wood, so surface temperature may differ significantly from air temperature.
• Start on the north side in morning (cooler surface, paint won't dry too fast), then move to south and west as those surfaces cool in afternoon.

Total Cost Estimate

For a typical Ottawa century home (approximately 2,000-2,500 sq ft of brick surface):

| Component | Cost Range |
|-----------|------------|
| Masonry repair (partial repointing) | $1,500-$5,000 |
| Cleaning | $300-$800 |
| Primer | $200-$400 |
| Paint (mineral silicate, 2 coats) | $600-$1,200 |
| Professional labour | $4,000-$8,000 |
| Total | $6,600-$15,400 |

Using standard elastomeric instead of mineral silicate reduces the paint material cost but not the labour, which is the majority of the expense.

Ontario Building Code Considerations

The Ontario Building Code doesn't specifically regulate exterior paint on existing residential masonry, but if your repointing or repairs involve structural elements, a building permit may be required. Heritage conservation districts have additional requirements under the Ontario Heritage Act — unauthorized changes to designated properties can result in orders to restore original condition.

For contractors experienced with Ottawa's century homes and heritage masonry, the Ottawa Construction Network directory is a valuable resource. And Ottawa Paint Contractors has a growing library of Paint IQ answers covering brick painting, heritage home considerations, and more.