Flagstone vs. Interlock: The Honest Truth About Longevity & Price

It is the classic debate in almost every landscape design consultation we host: “I love the look of natural stone, but is it worth the extra money? Or should I just stick with interlock?”

When you are looking at a 1,000-square-foot driveway or a backyard patio, the price difference between these two materials can equal the cost of a small car. It is a major decision.

At Tekton Landscapes, we install both. We don't have a bias, but we do have data. Here is the honest breakdown of Flagstone vs. Interlock pavers regarding price, longevity, and how they handle Toronto winters.

1. The Price: What Are You Actually Paying For?

Let’s rip the band-aid off first. Natural stone is more expensive—not just because the material costs more, but because the labor is significantly more intensive.1

Interlocking Pavers (Concrete)

• The Cost: Approx. $20 – $35 per sq. ft. (installed).

• The Labor: Interlock is modular. The pieces are uniform, meaning we can lay them quickly. Cutting is minimal compared to stone.

• The Value: You get a high-end look for a mid-range price.

Natural Stone (Flagstone/Limestone)

• The Cost: Approx. $35 – $65+ per sq. ft. (installed).2

• The Labor: This is masonry, not just paving. If we are doing a "wet lay" (mortar) installation, we need to pour a concrete pad first. If we are doing a "dry lay," every single piece often needs to be chiseled or saw-cut to fit the specific pattern. It takes 2-3x longer to install than interlock.

• The Value: You are paying for craftsmanship and a "forever" material.

2. The "Aging" Factor: Fading vs. Patina

This is the biggest differentiator that brochures won't tell you.

Interlock Fades.

Concrete pavers are dyed with pigments.3 Over 10-15 years, UV rays from the sun will break down those pigments. That "Midnight Black" driveway you installed will eventually turn charcoal grey. That "Red Clay" patio will soften to a muted pink/brown.

• Note: High-end manufacturers (like Unilock or Techo-Bloc) use better technology to slow this down, but no concrete product is immune to the sun.

Natural Stone Does Not Fade.

A piece of Eramosa Limestone pulled from the earth is the same color all the way through. It has already existed for millions of years; another 20 years in your backyard won't change it.

• Instead of fading, natural stone develops a patina. It might weather slightly, but it retains its richness.

3. Winter Survival: Heaving and Salt

Both materials can survive a Toronto winter, but they survive differently.

The "Flex" of Interlock

Interlock is a flexible system. It floats on a bed of gravel and sand. When the ground freezes and heaves in February, the pavers move with the ground.4 When the thaw comes in April, they settle back down.

• Risk: Over time, they can settle unevenly, requiring you to lift and re-level them (a relatively cheap fix).5

The "Rigidity" of Flagstone

Large slabs of flagstone are rigid. If the ground heaves underneath a large slab, it can crack.

• The Tekton Solution: This is why we often install natural stone on a concrete base with deep footings. We engineer the base so it cannot move.

• Salt Warning: Never use standard rock salt on natural stone. It will cause "spalling" (flaking). We only recommend magnesium chloride for our stone projects.

4. The Verdict: Which has the Better ROI?

The right choice depends on how long you plan to stay in the home.

Choose Interlock If:

• You plan to sell within 5–7 years. It looks clean, boosts curb appeal instantly, and costs less, giving you a better short-term return on investment.

• You want a driveway that can handle heavy abuse (oil drips, hockey pucks) without you crying over a stain.

Choose Natural Stone If:

• This is your "Forever Home." The cost amortized over 20 years is excellent because you will likely never have to replace it.

• You want a unique aesthetic. No two pieces of flagstone are identical. It signals "luxury" to buyers in high-end neighborhoods like Forest Hill or The Beaches.

Summary Comparison

FeatureInterlock PaversNatural Stone (Flagstone)Installed Cost$$($20-$35/sq ft)$$$$ ($35-$65+/sq ft)Labor TimeFast (3-5 days typical)Slow (2-3 weeks typical)UV ResistanceFades over timeNever fadesMaintenanceRe-sanding joints (3-5 yrs)Re-pointing mortar (10-15 yrs)AestheticUniform, StructuredOrganic, UniqueBest ForDriveways, Family PatiosFront Entrances, Luxury Terraces

Still Undecided?

Sometimes you have to see it to believe it. We can bring samples of high-end pavers and natural limestone to your home so you can compare them side-by-side against your brickwork.

Book a Material Consultation with Tekton and let’s find the right fit for your budget.