Toronto (Clanton Park): a nearly-bare attic with black mold overhead — a mid-winter full rebuild

1The Problem

This was one of the barest attics we’ve worked on — joists and dust where two feet of insulation should be. All that escaping heat carried moisture with it, and the roof sheathing above was blanketed in black mold.

2What the Inspection Found

The inspection mapped where all that moisture was coming from: unsealed penetrations letting house air pour into the attic, bathroom exhaust ducting that wasn’t insulated (so it dripped condensation), and a washroom vent that needed properly reconnecting. About 250 sq ft of sheathing needed full mold remediation.

3How We Fixed It

Cold weather doesn’t pause mold — so we didn’t wait for spring:

• Cleared and prepped the full 1,500 sq ft deck
• Completed the 3-stage mold remediation on 250 sq ft of sheathing — cleaning and spore removal, wood restoration, protective sealant
• Air-sealed the ceiling penetrations, including the plumbing stack
• Insulated both bathroom vent pipes and reconnected the washroom vent so steam exits through the roof
• Installed baffle vents with soffit cover-up
• Blew in fresh fiberglass from zero to R-60

4The Result

From heating the sky to holding heat: a bare attic went to a full R-60 blanket in the middle of February, with the mold remediated at its source. The furnace finally got to take a break.

5The Short Version

In the middle of February, a Clanton Park homeowner in North York was effectively heating the sky: 1,500 sq ft of attic with almost no insulation at all, an unsealed plumbing stack feeding warm humid house air upward, and heavy black mold across the roof sheathing to show for it. Confirmed Attics & Insulation cleared and prepped the full deck, completed a 3-stage mold remediation on 250 sq ft of affected sheathing — cleaning and spore removal, wood restoration, and a protective sealant — air-sealed the ceiling penetrations including the stack, insulated both bathroom vent pipes and reconnected the washroom vent so steam exits through the roof, installed baffle vents with soffit cover-up, and blew fresh fiberglass from zero to R-60. A mid-winter full rebuild that took the house from bare joists to a sealed R-60 blanket. Completed February 2026; 10-year workmanship warranty.