Thornhill Complete: A Roof, Insulation, and Chimney Rebuild in Seven Days

Key takeaways

• 4,000 sq ft executive home in Thornhill: full shingle replacement, attic spray-foam upgrade, chimney rebuild.
• Bundled into a single seven-day window with three crews working in sequence.
• Attic R-value increased from roughly R-22 (degraded blown cellulose) to R-50+ with closed-cell spray foam.
• Chimney crown had failed years earlier; rebuilt with new flashing tied into the new roof.
• Doing all three at once saved the owner on access costs, lift rentals, and dumpster days — roughly the cost of the chimney rebuild alone.

Why bundle the roof and the attic

When the roof comes off, the attic is the most accessible it will ever be — from above and from below. Most homeowners don't realize that. They replace the roof, the contractor leaves, and then a year later they realize their heating bill didn't drop and they call an insulation contractor who quotes them a fresh attic access setup.

Bundling the work means:

• One set of access logistics (lift, scaffolding, dumpster)
• One crew transition between trades — coordinated, not scheduled six months apart
• No risk of damaging brand-new shingles to install insulation later
• Chimney work happens in the small window when roof flashing is already open — way easier than retrofitting around new shingles

For this Thornhill home, the chimney rebuild alone would have been roughly $4,500 more if we'd come back for it separately — staging, masonry crew mobilization, and re-flashing a finished roof.

Day-by-day sequencing

Real-world day plan from this project:

1. 01

   Day 1: Tear off shingles, expose deck, inspect for damage. Decking was solid — three sheets needed swapping at a chimney saddle.

2. 02

   Day 2: Underlayment, ice-and-water shield, drip edge, vent boots prepped. Chimney crown demolition begins — old crown was cracked through.

3. 03

   Day 3: Masonry crew rebuilds chimney crown, repoints the top three courses, installs new flashing pan. Insulation crew prepares attic — old cellulose vacuumed out where it had settled.

4. 04

   Day 4: Closed-cell spray foam applied to underside of roof deck (creating a conditioned attic space). Roof crew works opposite slope.

5. 05

   Day 5: Shingles installed over the slopes completed by the foam crew. Step flashing woven into siding at all sidewalls.

6. 06

   Day 6: Roof finishing — ridge vent install, capping, sealant on all penetrations.

7. 07

   Day 7: Final walkthrough, photo documentation, gutter clean, site cleanup.

Closed-cell spray foam: the right call here

The owner had asked about three insulation options. Here's how we walked through them:

This attic had two HVAC trunk lines and three return ducts running through it. With blown cellulose, those ducts lose heat all winter and gain heat all summer. With closed-cell foam applied to the underside of the roof deck, the whole attic becomes part of the conditioned envelope — ducts are inside the building, not outside.

The payback math for this house penciled at roughly 6-8 years based on the owner's prior heating bills.

The chimney rebuild nobody saw coming

The chimney looked fine from the ground. From the roof, the crown — the concrete cap on top of the chimney — had a crack running diagonally across the full width. Water had been entering the chimney for at least a few years, freezing inside the brick in winter, and slowly spalling the top courses.

What we did:

• Demolished and removed the existing crown
• Repointed the top three courses of brick with type N mortar
• Poured a new crown with overhang and drip edge (most builders skip the overhang — it's the detail that keeps water off the brick face)
• Installed new lead counter-flashing woven into the new brickwork, not surface-caulked
• Fitted a new chimney cap to keep rain and animals out

This is the kind of work that gets ignored on roof replacements because it's not 'roofing' — but it's the most common source of top-floor leaks we see in older Toronto homes.

Bundled cost vs. piecemeal

Comparing bundled vs. piecemeal for this specific project (approximations, not a public quote):

The savings on this project came almost entirely from shared access costs and shared mobilization — not from anyone discounting their trade rate. Owner saved roughly the cost of the chimney rebuild itself.

What the owner walked away with

At project close, the owner received:

• Manufacturer warranty on shingles, foam, and chimney materials
• Workmanship warranty from Blue Knight on all three scopes
• Single point of contact for any issue — one number to call, not three
• Full photo documentation of deck condition, foam coverage, chimney rebuild stages, and final shingle install
• Updated insurance paperwork noting the upgraded envelope (worth pursuing — some insurers credit recent roof and chimney work)
• Maintenance schedule (annual gutter clear, biannual roof visual, chimney inspection every 3 years)