Interlocking brick driveways and patios are one of the most popular landscaping choices in Kitchener-Waterloo. But once the installation is done and the compliments from the neighbours roll in, homeowners quickly wonder: do I need to seal this? The answer is yes — but with important caveats about timing and product selection.
Benefits of Sealing Interlocking Brick
Sealing interlocking brick isn't just cosmetic. There are real protective benefits that extend the life of your investment and reduce maintenance over time.
Colour Enhancement and Preservation
Unsealed interlocking brick fades over time from UV exposure. The rich reds, charcoals, and tans that looked so vivid when first installed can look washed out and dull within a few years. A quality sealer with UV inhibitors locks in colour depth and prevents the gradual bleaching that Ontario's sunny summers accelerate. Wet-look sealers take this further, giving the brick a permanently rich, just-rained-on appearance that many homeowners love.
Joint Sand Stabilization (Weed Inhibition)
This is arguably the most practical benefit of sealing interlock. The polymeric sand in the joints between bricks is constantly under attack from wind, rain, foot traffic, and weed seeds. Without sealing, that joint sand slowly erodes, creating gaps where weeds, grass, and moss take hold. A penetrating sealer binds the top layer of joint sand together, creating a hardened surface that resists erosion and makes it far harder for weeds to root.
Homeowners who skip sealing often find themselves pulling weeds from between their bricks every summer — an endless and thankless maintenance task. Sealing dramatically reduces (though doesn't completely eliminate) this problem.
Stain Resistance
Interlocking brick is porous and absorbs liquids readily. Oil drips from vehicles, rust stains from metal furniture, tannin stains from fallen leaves, and general traffic grime all penetrate unsealed brick and become permanent. A sealer creates a hydrophobic barrier that causes liquids to bead and pool rather than absorb, giving you time to wipe spills before they stain.
Pro Tip: Even with sealer, oil stains should be blotted up immediately — sealer slows absorption but doesn't make interlock completely stain-proof. The protective window is typically 5–10 minutes for a heavily saturated sealer, longer as the sealer ages.
Freeze-Thaw Protection
In Ontario's climate, water that saturates the porous surface of unprotected brick can freeze and cause spalling — small chips and flaking on the brick surface. Sealing reduces the amount of water absorbed, thereby reducing freeze-thaw damage over time. This is particularly important for lower-quality concrete pavers that are more susceptible to surface degradation.
When NOT to Seal Your Interlocking Brick
This is where many homeowners make an expensive mistake: sealing too soon after installation. New interlocking brick must not be sealed for approximately 12 months after installation.
Here's why: concrete pavers go through a natural curing and weathering process during their first year. This process includes the release of efflorescence — mineral salts that migrate to the surface as the concrete cures. This white, chalky deposit is temporary and will wash away with rain and traffic if given time. But if you seal over it, you trap those salts beneath the sealer, permanently clouding and discolouring the brick surface in a way that is extremely difficult to correct.
Other situations where sealing may be inadvisable or require extra caution:
- Brick with existing haze or discolouration: Sealing over an unresolved efflorescence problem makes it permanent. The source must be identified and the surface cleaned with an efflorescence cleaner first.
- Brick in poor structural condition: Sealing over interlock that is shifting, sinking, or has unstable joints should wait until the base issues are corrected. Sealer doesn't fix structural problems.
- Very shaded, damp areas: Sealing brick that stays perpetually damp (under tree canopy with poor drainage) can trap moisture and encourage mold and algae growth beneath the sealer.
Types of Sealers for Interlocking Brick
Not all sealers are appropriate for interlocking brick. The two main categories — wet-look and natural/matte — differ significantly in appearance and performance characteristics.
Wet-Look Sealers (Film-Forming)
Wet-look or "enhancing" sealers create a high-gloss surface film that deepens and intensifies brick colour, giving the appearance of permanently wet brick. These are popular for their visual impact but have some practical considerations. Because they sit on the surface rather than penetrating the brick, they can peel as they age — particularly in areas with heavy traffic or exposure to de-icing chemicals. They also tend to make surfaces slippery when wet, which is a concern for pathways.
Natural/Matte Sealers (Penetrating)
Penetrating matte sealers soak into the brick rather than coating the surface. They preserve the natural appearance of the brick without adding sheen, and because they don't form a surface film, there's no peeling risk. For driveways and high-traffic areas, penetrating sealers are generally the more durable and practical choice, even if they're less dramatic-looking. The protection against staining and moisture penetration is comparable to wet-look products.
Solvent-Based vs. Water-Based
Both wet-look and penetrating sealers come in solvent-based and water-based formulas. Solvent-based products generally penetrate more deeply and provide better early performance, but they have strong odours and require careful handling. Water-based formulas are more environmentally friendly, easier to apply, and have improved significantly in quality over the past decade. For most residential applications, high-quality water-based sealers are now the preferred choice.
| Sealer Type | Appearance | Durability | Best For |
|---|---|---|---|
| Wet-Look (Film-Forming) | High gloss, deepened colour | Moderate (can peel) | Patios, lower-traffic areas |
| Natural/Matte (Penetrating) | Original brick appearance | High (no peeling) | Driveways, high traffic |
| Solvent-Based (either type) | Same as above | High | Maximum penetration |
| Water-Based (either type) | Same as above | Good–High | Eco-friendly preference |
The Application Process
Proper application of interlock sealer follows a specific sequence. Skipping steps — particularly around cleaning and joint sand — is the most common cause of a disappointing result.
Step 1: Clean Thoroughly
The brick must be completely clean before sealing. This means pressure washing to remove dirt, algae, and organic debris, followed by treatment of any stains with appropriate stain removers. Oil stains need a commercial degreaser. Efflorescence (white mineral deposits) needs an acid-based cleaner specific to concrete. Rust stains require oxalic acid treatment. Each stain type has a different chemistry, and using the wrong product can make stains worse.
Step 2: Ensure Joint Sand Is in Place
Before sealing, inspect all the joints between bricks. Any areas where joint sand has eroded need to be topped up with fresh polymeric sand, compacted, and allowed to cure according to the manufacturer's instructions. Sealing over empty or partially empty joints will lock in a gap that water can still exploit.
Step 3: Dry Completely
The brick must be completely dry — typically 48 hours after cleaning or rain. Sealer applied over damp brick will appear milky and won't bond properly.
Step 4: Apply Sealer in Thin, Even Coats
Apply sealer with a pump sprayer, then work it in with a squeegee or roller. Two thin coats are always better than one thick coat. Allow the first coat to flash off (typically 30–60 minutes in warm conditions) before applying the second. Avoid puddling or pooling — excess sealer forms a thick film that will peel.
"The biggest mistake homeowners make with interlock sealing is applying too much at once. They think more is better, but a thick application creates a surface film that peels within a season. Thin coats, properly applied, will outlast heavy applications every time."
— David, D&D Home Services Co-Founder
Reapplication Frequency
Interlocking brick sealer typically needs reapplication every 3–5 years, depending on traffic, sun exposure, and the quality of the original application. High-traffic driveways in full sun will need more frequent resealing than a shaded patio with foot traffic only.
The sign that resealing is needed is the same as with asphalt: perform the water bead test. Pour a small amount of water on the brick surface. If it beads and rolls off, the sealer is still functional. If it soaks in immediately, it's time to reseal. You'll also notice that sealed brick that is aging starts to look less vibrant and more like unsealed brick.
DIY vs. Professional Interlock Sealing
Interlocking brick sealing is more DIY-accessible than asphalt sealing in some ways, but also has specific pitfalls that make professional results superior.
For small patios (under 30 square metres) that are in good condition with intact joint sand and no significant staining, a motivated DIYer with the right materials can get good results. Products are readily available at landscape supply stores and are less hazardous than asphalt sealers.
For driveways, large patios, or any surface with staining, efflorescence, or depleted joint sand, professional service makes more sense. Professional rates for interlock sealing in Kitchener-Waterloo typically run $1–$3 per square foot, which includes the cleaning, sand assessment, and sealer application.
Key Takeaways
- ✓ Sealing provides real benefits: colour preservation, weed inhibition, stain resistance, and freeze-thaw protection.
- ✓ Wait 12 months after new installation before sealing — efflorescence must escape first.
- ✓ Penetrating/matte sealers are more durable for driveways; wet-look sealers work well for patios.
- ✓ Joint sand must be in good condition before sealing — top up any depleted joints first.
- ✓ Clean thoroughly before application — stains and efflorescence must be addressed before sealing.
- ✓ Reseal every 3–5 years; use the water bead test to determine timing.
D&D Home Services provides professional interlocking brick and driveway sealing services across Kitchener, Waterloo, Cambridge, and Guelph. Contact us for a free assessment and quote.
