Structural Engineering Review – Summary for Owners

To ensure the proposed metal‑over‑shingle roofing system is structurally safe for our 54‑year‑old buildings, the Board engaged Alex Structural, a licensed engineering firm, to complete a full structural assessment of the roof framing.

The engineer reviewed the original 1972 construction drawings, evaluated the existing roof truss system, and calculated the impact of adding a metal roof over the current shingles. As the report states, “The existing townhomes are light‑wood framed and constructed in the early 1970s… The roofs above are conventionally framed with gable roof trusses spanning in the long direction.”

Key Findings

1. Metal‑over‑shingle installation adds only a small amount of weight

The engineer calculated that the new metal roof assembly increases the roof’s dead load by only 0.05 kPa, resulting in a total load increase of just 2.2%.
The report confirms: “The proposed roofing system increases the total dead load… from approximately 0.50 kPa to 0.55 kPa… an increase of approximately 2.2%.”

2. The existing roof structure can safely support the added load

The engineer concluded that this small increase is well within the original design capacity of the roof trusses.
“This increase in loading is considered negligible relative to the original structural design capacity… no structural reinforcement… is required.”

3. No structural modifications are needed

Provided the existing framing and sheathing are in good condition, the metal roof can be installed without any reinforcement.

4. Installation must follow building code and manufacturer standards

The report outlines requirements for proper fastening, ventilation, flashing, and compliance with the Ontario Building Code 2024.

Conclusion

The engineering review confirms that installing a metal roof over the existing shingles is structurally acceptable for all units at 1616 Haig Boulevard. The added weight is minimal, the roof trusses can safely support the load, and no structural upgrades are required.

This independent engineering verification was a critical due‑diligence step and ensures the project meets all structural and safety standards.