This is one of the most common questions we see from GTA homeowners planning outdoor projects. Here’s an honest comparison from the perspective of having installed hundreds of both types.
The Core Difference
Interlock: Manufactured concrete paving units in standardized sizes. Consistent colour (within a batch), precise geometry, faster installation on large flat areas.
Flagstone: Natural stone in irregular shapes. Each piece is unique. More labour-intensive to lay. Warmer, more organic aesthetic.
When Interlock Makes More Sense
- Large driveway or parking area (faster to install, more uniform surface)
- Contemporary or modern architecture (clean lines, consistent units)
- Budget-conscious project (interlock is typically 20–40% less than equivalent quality flagstone)
- Heavy vehicle traffic areas (interlock distributes load well)
When Flagstone Makes More Sense
- Heritage or traditional architecture (Victorian, Edwardian, craftsman)
- Backyard patios where aesthetics outweigh cost
- Irregular shapes or curved layouts (flagstone’s natural irregularity suits organic designs)
- Smaller areas where the premium per-sq-ft cost is manageable
The Maintenance Reality
Both require periodic attention. Interlock: resand joints every few years, reset heaved units after severe winters. Flagstone: occasional repointing or stone resetting, seal natural stone for easier cleaning.
What’s your project — interlock or flagstone? Post the details below and the community can weigh in.