Thornhill Homeowner: Interlock and Flagstone Backyard Patio 2026

Just finished our backyard project in Thornhill (between Yonge and Bathurst, York Region side). Sharing because I found almost no detailed Thornhill-specific outdoor renovation content when I was planning.

Our situation:
Late 1990s detached, large 60-foot wide lot, the backyard was a blank slate — just grass and an old wooden deck that had rotted beyond repair.

What we built:

  • Removed old deck (4 loads of debris)
  • 500 sq ft interlock patio (Techo-Bloc Borealis, charcoal colour)
  • Flagstone pathway from side gate to patio (Brampton Stone irregular limestone)
  • Low armour stone retaining wall along back of property (grade change of about 18 inches)
  • Pergola over main patio area (aluminum, powder coated, with sun shade fabric)
  • New cedar fence (replaced 3-board sections)

Who we used:
LF Builders (lfbuilders.ca) for the interlock, flagstone, and armour stone — they’ve been doing work in our neighbourhood for decades and the neighbours all seem to have used them at some point. The pergola was a separate contractor.

Costs:

Item Cost
Interlock patio (500 sq ft) $23,500
Flagstone pathway $5,800
Armour stone wall $7,200
Pergola $11,400
Cedar fence (3 sections) $4,100
Total $52,000

Very happy with the result. First spring since completion and the interlock has settled perfectly — no shifting, excellent drainage.

home.renovation.reviews for more outdoor renovation projects across the GTA.