Commercial roofs in Detroit face some of the toughest conditions anywhere in the country. From heavy snow loads to windstorms, freeze–thaw cycles, and industrial pollutants, a roofing system must withstand continuous challenges. Businesses insured by FM Global—one of the largest commercial property insurers in the world—must meet specific, rigorously engineered roofing performance standards to minimize risk and prevent loss.

Understanding FM Global requirements is crucial for facility managers, property owners, architects, and contractors. These standards influence everything from material selection to installation methods, fastening patterns, fire ratings, drainage, wind uplift resistance, and maintenance expectations. At Motor City Roofers, we specialize in helping Detroit companies meet FM-approved specifications and maintain compliance for long-term performance and insurance protection.

1. What Is FM Global and Why Does It Matter?
FM Global is a commercial property insurance company known for its engineering-based approach to loss prevention. Rather than simply writing policies, FM Global develops stringent standards—called FM Approvals—for construction materials, assemblies, and installation methods.
For roofing, FM Global evaluates:

• Fire resistance
• Wind uplift performance
• Hail impact resistance
• Durability and material quality
• Proper installation methods
• Resistance to punctures, tears, and environmental hazards

If your facility’s insurer requires compliance with FM Global standards, your roofing system must meet the corresponding FM rating—or risk higher premiums, denied claims, or unsafe roofing performance.

2. Key FM Ratings for Commercial Roofs
FM Global assigns roofing systems specific ratings based on their tested performance. The most common designations include:

FM 1-29: Roof Deck Securement
This standard governs how roofing systems are attached to structural decks. It outlines fastener spacing, attachment patterns, and corrosion-resistance requirements. Following FM 1-29 ensures that roofing assemblies remain secure during high winds, vibration, or structural movement.

FM 4470: Approval Standard for Single-Ply, Built-Up, Modified Bitumen, and Liquid-Applied Roof Systems
This is one of the most important standards for commercial roofing. FM 4470 evaluates:

• Fire performance
• Wind uplift resistance
• Hail resistance
• Simulated aging and durability
• Water leakage resistance

For a roof system to be FM Approved, each component—insulation, membrane, adhesive, fasteners—must pass FM 4470 tests. Motor City Roofers uses FM-Approved systems that meet or exceed these performance thresholds.

FM 1-60, 1-75, 1-90 (Wind Uplift Ratings)
These ratings describe how much wind uplift pressure a roof assembly can withstand:

• 1-60 = 60 pounds per square foot
• 1-75 = 75 pounds per square foot
• 1-90 = 90 pounds per square foot

In Detroit, where winter storms and high winds are common, most commercial buildings require FM 1-75 or FM 1-90 assemblies to comply with insurance requirements and ensure safety.
FM Global Hail Resistance (Class 1 SH, MH, LH)FM evaluates roofing against hail impact:

• SH = Severe hail
• MH = Moderate hail
• LH = Light hail

Many Detroit facilities require MH due to Midwest storm patterns, but industrial buildings with large roof areas often choose SH for maximum protection.

3. Key Factors FM Global Requires for Roof Compliance
A. Approved Material Combinations
FM does not just approve individual materials—it approves entire roofing assemblies. That means insulation, adhesives, membranes, and fasteners must be tested together. Motor City Roofers always verifies that all components installed meet the appropriate FM Approved combinations.

B. Proper Fastener Density and Installation
Wind uplift performance greatly depends on how fasteners are spaced, especially at:

• Roof perimeters
• Corners (highest wind load areas)
• Edges near parapets
• Transitions and mechanical curbs

FM standards specify enhanced fastening zones. Improper fastener spacing is one of the most common reasons roofs fail FM inspections—and why hiring certified installers like Motor City Roofers is essential.

C. Fire Resistance Ratings
FM assigns fire ratings to roof assemblies, and many insurance policies require:

• Class 1 fire resistance for most commercial roofing systems
• Fire-resistant insulation and cover boards

We ensure all systems installed achieve the fire-class rating required by your policy or facility type.

D. Proper Drainage Requirements
FM Global mandates that flat roofs have:

• Adequate slope
• Redundant drainage
• Clear pathways for stormwater

Standing water increases load, damages membranes, and leads to premature failure. Motor City Roofers designs drainage systems that exceed FM expectations by incorporating tapered insulation and regularly spaced drains.

E. Edge Metal and Perimeter Securement
FM 1-49 covers edge systems. Roof edges are the most vulnerable areas during windstorms. FM requirements dictate:

• Stronger fastening
• Securement plates
• High-performance edge metal systems

Our perimeter assemblies always meet or exceed FM wind load factors.

4. Common FM Global Roofing Requirements for Detroit Facilities
Because Detroit has heavy snow, strong winds, and occasional hail, FM requirements often include:

• FM 1-90 wind uplift ratings
• FM SH hail classification
• Thicker insulation (higher R-value)
• Reinforced single-ply or modified bitumen membranes
• Cover boards for puncture resistance
• Enhanced fastener density in perimeter zones

Manufacturing plants, cold storage warehouses, and distribution centers frequently require full FM compliance to maintain insurance coverage.

5. FM Roof Inspections and Documentation
FM Global conducts engineering site visits where they verify:

• Roof system matches approved FM assembly
• Fastener spacing is correct
• Fire­­-resistant materials are used
• Drainage is up to code
• Penetrations are flashed properly
• Maintenance plans are in place

Motor City Roofers provides:

• Complete FM assembly documentation
• Detailed installation photos
• Fastener pattern verification
• Warranty packets
• Maintenance programs to ensure ongoing compliance

This documentation protects your business from insurance issues and provides proof of proper installation.

6. Benefits of FM-Compliant Roofing Systems
Choosing FM-Approved roofing provides:

• Lower insurance premiums
• Reduced risk of wind or fire damage
• Better protection against hail
• Longer roof life
• Improved safety for buildings and occupants
• Peace of mind knowing the roof meets world-class engineering standards

For large warehouses, manufacturing facilities, or multi-building campuses, FM compliance can save thousands annually in operational and insurance costs.

7. Why Work With Motor City Roofers for FM-Approved Roofing
Detroit businesses trust Motor City Roofers because we:

• Specialize in FM-Approved commercial roof systems
• Follow every FM requirement during installation
• Provide compliance documentation for insurance
• Offer FM-compatible replacements, repairs, and upgrades
• Install wind-rated and hail-rated systems tailored to Michigan conditions

We work directly with FM engineers when needed to ensure your building meets all current standards.

Conclusion: FM Requirements Protect Your Roof—and Your Business
FM Global roofing standards are not simply checkboxes—they are engineered safeguards designed to prevent catastrophic damage. For Detroit’s industrial, commercial, and manufacturing facilities, compliance is a smart investment that reduces risk, improves durability, and ensures long-term performance.

At Motor City Roofers, we bring the expertise and precision necessary to install and maintain roofing systems that fully meet FM Global requirements. Whether you are replacing an existing roof, upgrading to FM compliance, or preparing for an FM audit, our team is ready to support your project from start to finish.