Commercial roofing systems are the materials for flat and low-slope roofs at offices, retail and industrial sites. In Calgary, cold snaps, hail and chinooks demand tough roofs that seal well and drain quickly.
Angel’s Roofing installs and services TPO, EPDM, PVC, and SBS-mod bit with CSA-approved materials and COR safety. Crews deliver over 25 years of experience, transparent bids, and rigorous quality inspections.
To learn more or schedule a complimentary estimate, please contact our Calgary team.
Key Factors for Your Commercial Roof
Calgary’s freeze-thaw cycles, hail, chinooks, and UV swings are complex on flat and low-slope roofs. Informed decisions early and consistent maintenance post-installation help these costly assets thrive.
Identify the unique roofing needs of your commercial building, including the type of roof, slope, and intended use.
Start with use: warehouses require puncture resistance and fast leak detection, offices demand thermal comfort and quiet, and restaurants require strong grease and vent protection.
Map roof type and slope; true flat to low-slope (0:12–3:12) drives membrane choices, drainage layout, and snow load paths. Designate traffic areas surrounding HVAC units, skylights, and solar arrays with walk pads and reinforced sheets.
For steep and/or metal fascias, flash expansion joints and ice-dam control at eaves.
Evaluate commercial roofing materials based on their durability, weather resistance, and energy efficiency in your specific climate.
Typical systems in Calgary include EPDM rubber for its proven flexibility, TPO and PVC single-ply for weldable seams and cool-surface energy gains, BUR for multi-ply redundancy, modified bitumen for high-temperature swing tolerance, and metal for a 40–60 year lifespan with proper details.
Combine with insulation—polyiso remains the preferred platform for R-per thickness and price—using tapered crickets to direct meltwater toward drains.
Consider cool membranes and vegetated assemblies to reduce heat gain, minimize stormwater runoff, and even out HVAC loads. Validate hail ratings, fire class, chemical resistant near stacks, warranty, etc.
Prioritize regular maintenance programs and scheduled roof inspections to extend the lifespan of your commercial roofing system.
Take a twice-a-year approach — spring and fall — plus post-hail inspections. Clear drains, reseal terminations, repair punctures and document moisture scans.
Regular maintenance typically extends the service life of most systems into the 30–50 year range and prevents crisis shutdowns.
Select a qualified commercial roofing contractor with proven expertise in flat roof installations and repairs.
Vet Calgary-based crews with manufacturer certifications for TPO, PVC, EPDM, BUR, modified bitumen and metal. Demand project references, safety metrics and detailed scopes.
Lock in manufacturer system coverage and a written workmanship warranty with transparent term lengths and response times.
Top Flat Roof Systems
Calgary’s commercial flat and low-slope roofs, ranging from ¼:12 to 3:12 pitch, face freeze–thaw cycles, hail, and high UV exposure. Material selection, detailing, and insulation approach dictate long-term expense and hazard.
TPO, EPDM, PVC, and Modified Bitumen: Performance and Cost
TPO provides heat-welded seams, bright white reflectance, and excellent tear and puncture resistance. It suits food, retail, and light industrial roofs seeking energy savings and cleanliness.
EPDM, a thermoset rubber, comes in two membrane types: fully adhered and mechanically fastened. It tolerates movement and cold well, with large sheets that minimize the number of seams.
PVC offers strong heat-welded seams, excellent chemical and grease resistance, and outstanding UV performance — ideal for restaurants, laboratories, and plazas.
Modified bitumen utilizes factory-modified asphalt (SBS for flexibility and APP for UV and heat resistance) in multi-ply configurations, delivering toughness against hail and foot traffic with straight-line, easy repair pathways.
Budget ranges vary by deck, insulation, access, and other factors, but single-ply often has a lower initial cost; multi-ply Mod Bit tends to be higher upfront but rates well in terms of durability.
Single-Ply vs. BUR: Suitability by Project
Single-ply membranes—specifically, thermosets (EPDM) and thermoplastics (TPO, PVC)—have experienced significant growth over the past 40 years, driven by their speed, lighter loads, and proven assemblies. They’re great for large roofs that require fast installations and energy credits.
BUR, built-up roofing, consisting of layered bitumen and fabric, has served North America for over 100 years. It provides redundant waterproofing, mass for hail and fire protection, and tough surfacing options.
Opt for single-ply for tight timelines, load limit-based re-roofs, and reflectivity targets. Select BUR for high-traffic areas, hard-hail corridors or odour-tolerant locations with stringent durability requirements.
Coatings, Reflective Surfaces, and Insulation
Elastomeric coatings (acrylic, silicone, polyurethane) provide UV protection, extend service life and can add a reflectance boost to aged membranes or Mod Bit caps. Reflective surfaces reduce heat gain, potentially lowering cooling loads.
Insulation (polyiso above deck, as is typical in Calgary) provides both energy savings and slope; improper detailing can create water traps, so vapour control and quality tapers are crucial.
Top flat roof systems are the ultimate in practicality — green roofs add thermal mass, manage stormwater, and expand green space. Still, they require a structural review, root barriers, and thick, durable waterproofing.
| System | Key Features | Lifespan | Maintenance |
| TPO | Welded seams, reflective, mould-resistant | 20–30 years | Annual seams/flashing checks |
| EPDM | Large sheets, flexible, cold-tolerant | 20–30 years | Seam/tape and penetration checks |
| PVC | Chemical-resistant, welded seams | 20–30 years | Flashings, rooftop grease control |
| Mod Bit | Multi-ply, hail tough, SBS/APP options | 20–30 years | Granule, lap, and flashing care |
| BUR | Redundant plies, heavy-duty surfacing | 20–30+ years | Surfacing renewal, cut-and-patch |
| Coated Roof | UV shield, life extension | 5–15+ years add-on | Recoat cycles, prep critical |
| Green Roof | Stormwater, energy, amenity | Membrane life extended | Vegetation and drainage upkeep |
The Case for Metal Roofing
Steel roofing suits Calgary’s weather and business needs. It delivers strength, consistent performance, and reliably calculated lifecycle costs across warehouses, retail plazas, offices, and light industrial sites.
Durable, Low-Maintenance Protection for Hail and Wind
Metal roofs hold up to hail and chinook-driven gusts on the Prairies. Built with corrugated galvanized steel—steel sheet coated with zinc—steel roofing assemblies resist corrosion and denting. Panel systems have been tested to withstand wind speeds exceeding 240 km/h (150 mph).
When properly fastened and snow-retained, seams stay tight, and water sheds fast on low- to moderate-slope decks. Routine care is simple: seasonal checks of fasteners, sealant points, and gutter runs. Anticipate service lives roughly double those of many standard systems, slashing tear-off cycles and unexpected downtime.
Energy Efficiency and Heat Reflectivity That Cuts Costs
Cool Metal Roofs with Reflective Coatings Bounce Solar Heat & UV. Here in Calgary’s high-elevation sun, this keeps roof surface temperatures lower and helps reduce cooling loads in the summer.
In winter, continuous insulation below the deck and thermally broken clips help minimize heat loss and reduce the risk of ice dams. Owners experience a more stable interior temperature and reduced utility peaks, which is extremely important for large floor plates, such as distribution centers and grocery stores.
Options for Every Roof Slope and Building Type
Options span from standing seam (mechanically seamed or snap-lock) for low-slope commercial roofs, through-fastened steel panels for budget-driven retrofits, to aluminum systems for coastal or high-chemical locations.
Profiles, gauges and coatings can align with brand standards and snow-shed requirements. Metal roofs come in various sizes and price points, with colours and finishes that match corporate façades.
Long-Term Value, Warranties, and Practical Tradeoffs
Longevity, energy savings, and recyclability all combine to make metal a wise investment. Most come with 30–50-year finishes and weather-tight warranties, far outpacing asphalt shingles.
Drawbacks exist, including higher upfront costs, potential noise without acoustic underlayment, and the need for detail-sensitive installations. Even so, the upward trend in adoption highlights benefits that do exist relative to conventional materials.
Beyond the Membrane: Hail & Wind
Commercial roofs in Calgary endure rapid weather swings. Hailstorms are random. High winds, UV and extreme cold and heat add stress. Designs and specs must anticipate impact and uplift from the very first day.
Impact Resistance in Hail-Prone Zones
Tested for heavy impact on select systems. In Alberta, bigger hail can bruise insulation, smash felts and crack coatings. Search for FM Global Severe Hail (SH) or UL 2218 Class 4 assemblies, not just membrane ratings.
For maximum protection, apply high-density cover boards—polyiso HD, gypsum fibre, or cement board—over your insulation to help distribute impact and slash puncture. Seam placement is important; avoid seams near drains and traffic ways.
Windward mountain slopes bear the brunt, while leeward sides sustain less. After storms, inspect for crushed granules, surface spalls and split flashings. Ponding for 48 hours or more indicates drainage problems that are exacerbated by hail and wind.
Wind Ratings, Edge Security, and Field Uplift
Winds in one storm will blow from a single dominant direction, making the corners and edges bear the brunt. Failures begin at the corners, then the edges, and then the field. Designate FM 1-90 or above by exposure and height, with corner and perimeter protection as per FM 1-29.
While high winds can lift/tear single-plies, causing punctures and leaks, use tested mechanical fastener patterns or full-adhered systems with proven pull-off values. Use heavy-duty edge metal and term bars ANSI/SPRI ES-1!
Strap down rooftop units and curb flashings — loose equipment is debris.
Surface Protection and Coatings
Protective layers increase resistance to hail and wind-borne debris. Mineral cap sheets, granule-surfaced SBS and fleece-backed single-plies over HD boards take hits better than bare thin films.
Elastomeric roof coatings (silicone or high-solids acrylic) provide a sacrificial layer, enhance UV resistance and seal micro-cracks. Ensure the substrate is dry, primed, and reinforced at seams. Maintain drains to prevent ponding.
- SBS-modified bitumen with HD cover board
- TPO or PVC, fleece-backed, fully adhered w/HD board
- BUR mineral cap, strong edge metal
- Fluid-applied reinforced membrane systems
- Standing seam metal with interlocking panels and tested clips
Why Insulation Matters More Here
Calgary’s extreme fluctuations from deep-freeze winters to hot, dry summers mean that flat and low-slope commercial roofs are put under severe strain. Insulation is the first layer of control. It slashes heat loss in January, throttles heat gain in July, and regulates indoor temperatures in between, so the HVAC runs less, and bills drop.
On big roof plates, even minor R-value increases add up to substantial energy savings and reduced greenhouse gas emissions. Sound insulation prevents warm interior air from making contact with cold roof decks, so you don’t get condensation, wet decks and trapped vapour.
Dry assemblies also result in fewer membrane blisters, reduced freeze-thaw damage, and improved fastener hold over time, which minimizes leaks and increases membrane longevity — whether the roof is made of SBS, EPDM, TPO, or PVC.
In high-humidity areas inside the building, such as pools, kitchens, and labs, insulation with the appropriate vapour control reduces mould risk and maintains air quality. It also aids in noise reduction, muffling rooftop mechanical noise and rain impact.
Types of Insulation
- Polyisocyanurate (Polyiso): High R-value per millimetre, good compressive strength for traffic and pavers, available with foil or coated facers. Performs well above deck in Calgary’s cold climate. Hinges on proper facer selection for single-ply bonding.
- Extruded Polystyrene (XPS): Strong, moisture-resistant, steady R-value when exposed to wet cycles. Found in PMR assemblies under ballast. Combine with similar membranes and verify long-term retention.
- Expanded Polystyrene (EPS): Cost-effective, stable, light. Suitable for tapered systems to direct drainage to scuppers and internal drains. Choose higher densities for compressive requirements.
- Mineral Wool: Non-combustible, sound-absorbing, and vapour-open. Handy beneath fire-rated assemblies or where noise control counts. It is typically sandwiched with Polyiso to balance R-value and fire performance.
Specification for Property Managers
Property managers should specify insulation performance with the same weight as membrane choice, targeting code-plus R-values. They should verify compressive strength for traffic, confirm facer compatibility with the chosen adhesive or fasteners, detail continuous air and vapour control, and use tapered layouts to prevent ponding.
Request published LTTR, FM approvals, and a complete assembly warranty from the membrane and insulation manufacturers.
Navigating Warranties and Bylaws
Commercial roofs endure long winters, hail and wide temperature swings in Calgary. Robust warranty coverage and clean bylaw compliance reduce risk, manage lifecycle costs and safeguard operations.
Manufacturer vs. Workmanship: What Each Covers and Why It Matters
The manufacturer’s Warranty protects against premature membrane blistering, cracking, or failed coatings under regular use. Not poor installs, not abuse, not ignored maintenance.
The Workmanship Warranty covers the contractor’s errors in installation, including seam fishmouths, loose terminations, poor flashing tie-ins, and improper fastener patterns. On low-slope systems such as TPO, EPDM, and SBS-mod bit, both are required.
A good warranty protects owners from sudden roofing issues—provided inspections, cleanings, and minor repairs are performed on schedule. To maintain valid claims and short timeframes, file issues quickly with the warranty or your insurer.
Calgary Bylaws and Codes: What to Know Before You Build
The City of Calgary utilizes the Alberta Building Code and supplements it with municipal regulations tailored to our local climate and specific roof types. Key items for commercial projects include:
- Permits: Required for new roofs, structural changes, and many replacements. No permit can mean stop-work orders, fines, and retroactive fees.
- Drainage: Roof drainage systems sized for local snowmelt and storms; scuppers and overflows often needed on parapet roofs.
- Ice Dams: Protect eaves and transitions from ice dams with heat tracing or enhanced insulation/air sealing in problem zones.
- Fire/Structure: Roof coverings and assemblies must meet fire ratings and structural loads for snow and wind.
- Energy: Thermal performance and vapour control to reduce condensation and heat loss.
Build Complete Coverage: Materials and Labour Working Together
Obtain a system warranty that combines materials and installation under one document when feasible (i.e., manufacturer “NDL” coverage with certified installers). Verify wind uplift rating, ponding water language, hail resistance, and leak response times.
Remember, maintenance logs, missed service void coverage.
Pre-Start Checklist: Warranty and Compliance
- Verify permit scope and inspections with the City of Calgary.
- Ensure code compliance for drain, ice dam protection, fire rating and insulation.
- Obtain written Manufacturer’s and Workmanship warranties; note terms/years.
- Check exclusions: ponding limits, foot traffic, and rooftop equipment work.
- Require manufacturer-approved details at penetrations and edges.
- Specify leak response times and cap on owner costs.
- Schedule semi-annual maintenance with photo reports.
- Report defects or leaks immediately to the warranty provider/insurer.
Conclusion
Calgary weather poses a challenge to every roof: heat swings, hail strikes, and chinook winds. A good strategy protects your commercial roofing systems from the elements. The right system reduces leaks, reduces heat loss, and reduces stress for your team.
Angel’s Roofing has over 25 years of experience on local jobs. TPO on the big box roofs, SBS on the schools, and metal on the shops along Deerfoot. We select the appropriate specifications, comply with the code, and protect the crews. We monitor hail risk, wind loads, R‑values and fire ratings. We back the work and the warranty.
Want it straight about your roof? Need a straightforward, line-item bid? Contact Angel’s Roofing for a complimentary site inspection and estimate. Or schedule a consultation to discuss options, budget and timelines.
