Commercial Roofing FAQ for Markham Businesses

How often should a commercial flat roof be inspected?

Commercial flat roofs in Markham require inspection at least twice annually—typically in spring and fall. Ontario's harsh freeze-thaw cycles place exceptional stress on roofing membranes, flashing, and drainage systems. Spring inspections identify winter damage from ice damming and snow load, while fall inspections ensure your roof is ready for the upcoming winter season.

Beyond scheduled inspections, examine your roof after severe weather events including heavy snow accumulation, ice storms, or high winds. Early detection of ponding water, membrane punctures, or compromised seams prevents minor issues from escalating into costly interior damage.

What is the typical lifespan of different commercial roofing systems?

Lifespan varies significantly based on material choice and maintenance practices:

• Built-Up Roofing (BUR): 15-30 years with proper maintenance
• Modified Bitumen: 20-25 years when properly installed
• EPDM Rubber: 20-30 years depending on membrane thickness
• TPO Single-Ply: 15-25 years with quality installation
• PVC Membrane: 20-30 years in ideal conditions

Climate conditions in Markham can reduce these estimates if preventative maintenance is neglected. UV exposure, temperature extremes, and moisture infiltration accelerate membrane degradation.

Do I need permits for commercial roof replacement or repairs?

Most commercial roofing projects require building permits from the local municipality. Full roof replacements, structural modifications, and significant repairs typically need permit approval to ensure compliance with Ontario Building Code requirements. Even roof-mounted equipment installations often require permits and engineering stamps.

Your roofing contractor should handle permit applications and coordinate inspections. Working without proper permits can result in fines, insurance complications, and difficulties when selling your property. Always verify your contractor is licensed and familiar with local permit requirements.

What causes ponding water on commercial flat roofs?

Ponding water—standing water that remains 48 hours after rainfall—results from inadequate drainage slope, clogged drains or scuppers, structural deflection, or improper installation. While called "flat," commercial roofs should maintain minimum slope (typically 1/4 inch per foot) directing water toward drainage points.

Chronic ponding accelerates membrane deterioration, increases leak risk, promotes algae growth, and adds unnecessary structural load. Addressing drainage issues often requires tapered insulation systems, additional drains, or cricket installations to redirect water flow.

Should I repair or replace my commercial roof?

This decision depends on roof age, damage extent, and long-term building plans. If your roof has less than 30% damage and hasn't reached its expected lifespan, targeted repairs often make financial sense. However, if you're experiencing multiple leaks, extensive membrane deterioration, or the roof exceeds 75% of its expected life, replacement delivers better value.

Consider roof coating systems as a middle option. Elastomeric or silicone coatings can extend roof life by 10-15 years when applied to structurally sound membranes, providing significant cost savings compared to full replacement.