Ponding water that takes days to drain
Low spots or blocked drains. Tapered insulation or drain work extends the roof's life.
Roofing · Commercial and strata roofing
Commercial and strata roofing
Commercial and strata roofs are mostly flat or low-slope, which means membranes: two-ply torch-on SBS, single-ply TPO or EPDM, sometimes a metal roof on an agricultural or industrial building, and coatings to extend the life of a roof that isn't ready for replacement. These jobs need contractors with the right crews, safety plans and insurance, and strata councils usually need a condition report and more than one quote before they can approve the spending.
- Torch-on SBS about $9 to $16 per sq ft
- TPO about $8 to $14 per sq ft
- EPDM about $7 to $13 per sq ft
- Permits strata and commercial roofs are treated differently from houses in several municipalities
Warning signs
How serious is it?
Blisters, open seams or alligatoring in the membrane
The membrane is aging. Repairs and a coating may buy years; a condition report will say.
Staining or drips at rooftop units and parapets
Flashing failures at penetrations. The most common commercial leak.
Leaks into tenant space
Tarp or temporary repair, document for insurance, then a full assessment.
No maintenance record
Twice-yearly inspections and drain clearing are cheaper than any emergency repair.
Options
Commercial roofing options
| Option | What it is | Good for |
|---|---|---|
| Two-ply torch-on SBS | Two layers of modified bitumen membrane, the cap sheet torched down. | The Lower Mainland standard for flat roofs on strata, retail and small commercial buildings. |
| TPO single-ply | A white reflective membrane, heat-welded at the seams. | Large flat roofs, warehouses, buildings where a cooler roof helps. |
| EPDM single-ply | A black rubber membrane, glued or mechanically fastened, seams taped. | Lower-cost flat roofs, garages and additions. |
| Metal roofing | Standing seam or screw-down steel panels. | Agricultural, industrial and some retail buildings with sloped roofs. |
| Roof coatings | Elastomeric or silicone coating over an existing sound membrane. | Extending the life of a roof that isn't ready for replacement. |
Local conditions
Flat roofs in a wet climate
A flat roof here is really a very shallow slope with drains, and everything depends on the water getting to the drains. Ponding water, clogged drains, failed seams and flashing at parapets and rooftop units are where membranes fail. Membrane roofs have a predictable life, so a maintenance program with twice-yearly inspections and drain clearing is cheaper than emergency repairs in February.
Several Lower Mainland municipalities treat roof and envelope work on multi-family and commercial buildings differently from houses, often requiring a permit and a registered professional. Ask the municipality early, and make sure quotes say who is handling it.
What a good quote includes
- Membrane system and manufacturer, with the warranty they offer
- Insulation and tapered insulation to fix ponding, if needed
- Drains, scuppers, parapets and rooftop unit flashing
- Safety plan, WorkSafeBC coverage and liability insurance for the building type
- Tenant or resident access, noise and smell management (torch-on in particular)
- Permit and professional involvement where the municipality requires it
- Maintenance program after installation
Watch for: A single quote presented to a strata council. Most strata bylaws and good practice call for several, and the reserve fund study should match.
Costs
Typical commercial and strata roofing prices
| Job | Typical range | What moves the price |
|---|---|---|
| Two-ply torch-on SBS | $9 to $16 per sq ft | The local standard for flat roofs |
| TPO single-ply | $8 to $14 per sq ft | Large roofs, reflective white membrane |
| EPDM single-ply | $7 to $13 per sq ft | Budget rubber membrane |
| Flat roof replacement, 1,500 sq ft | $9,000 to $22,000 | EPDM at the low end, torch-on at the high end; insulation and drains extra |
Budget ranges in CAD before GST, from prices published by Lower Mainland roofers in October 2026. Your quotes are based on a site visit.
Questions
Commercial and strata roofing questions
Torch-on, TPO or EPDM?
Two-ply torch-on SBS is the local standard and forgiving of small flaws. TPO is lighter, white and welded, common on larger roofs. EPDM is the budget rubber option. The right one depends on the roof size, the deck, insulation and the contractor's experience.
Do strata roofs need a permit?
Often, and several Lower Mainland municipalities treat multi-family and commercial roof work differently from houses, sometimes requiring a registered professional. Ask the municipality early and make sure quotes say who handles it.
Can a coating extend the life of our flat roof?
If the membrane is sound and dry, an elastomeric or silicone coating can add years at a fraction of replacement cost. It won't fix wet insulation, failed seams or ponding. A condition report should come first.
How many quotes should a strata get?
At least three, with the same scope, and ideally after an independent condition report so every contractor is pricing the same roof. Reserve fund studies and depreciation reports should line up with the timeline.
Often done together
Guides
Commercial and strata roofing by area
Metro Vancouver
- Vancouver →
- Surrey →
- Burnaby →
- North Vancouver →
- Coquitlam →
- Delta →
- Richmond →
- West Vancouver →
- White Rock →
- Port Coquitlam →
- New Westminster →
- Port Moody →
Fraser Valley
- Chilliwack →
- Abbotsford →
- Langley →
- Maple Ridge →
- Mission →
- Pitt Meadows →
- Hope →
- Agassiz →
- Harrison Hot Springs →
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