Wind is one of the most important forces a commercial roofing system must withstand. Understanding how wind affects commercial roofs helps building owners see why the roof membrane, insulation, fasteners, deck, and attachment pattern all need to work together. A commercial roof is exposed to different wind pressures depending on the building’s height, location, shape, surrounding conditions, and roof configuration. The fastening system is one of the components that helps transfer those forces through the roofing assembly and into the structure.
Great Lakes Roofing knows that proper attachment is about more than simply selecting a fastener and installing it into the roof deck. The fastening system needs to be appropriate for the specific roofing assembly and building conditions. Fastener type, spacing, substrate, attachment pattern, and installation all influence how the completed roof performs when exposed to wind.
What Is Wind Uplift?
Wind uplift is the force that attempts to pull a roofing assembly upward when wind moves across and around a building. According to ANSI/SPRI, wind moving around a building can create a reduction in air pressure above the roof while pressure inside the building can contribute to forces acting upward on the roof assembly. Wind can also enter beneath roof edges and contribute to uplift forces.
This is important because a commercial roofing system must resist more than its own weight. It needs to remain securely attached when wind creates forces that work against the attachment system.
The amount of uplift a roof must resist is not the same for every building. Design calculations consider factors such as wind speed, building height, building shape, roof geometry, and exposure. ANSI/SPRI’s current WD 1 standard identifies different design areas across a roof, including field, perimeter, and corner areas, because wind pressures can vary across the roof surface.
Why Commercial Roof Fastening Systems Matter
Fasteners help connect components of a mechanically attached roofing system to the underlying structure. Depending on the roof design, mechanical fasteners may secure insulation, cover boards, membrane attachment components, or other parts of the assembly.
The important point is that the fasteners do not work independently. Their performance depends on the materials they are securing and the substrate into which they are installed.
For example, a fastener installed into a particular roof deck has to provide adequate withdrawal resistance for the loads expected on that building. The insulation and membrane attachment also need to perform as part of the tested or engineered roof assembly.
ANSI/SPRI’s wind design standard explains that the suitability of a roofing assembly is determined by comparing the calculated wind uplift pressures for a building with the tested wind uplift capacity of the roofing assembly.
That means we cannot determine wind performance simply by looking at the number of fasteners installed. The entire attachment system needs to be considered.
Fastener Spacing Can Affect Wind Performance
Fastener spacing is another important part of commercial roof design. The distance between fasteners affects how much of the roofing assembly each attachment point is responsible for securing.
Research and testing have demonstrated that changes in fastener placement can significantly affect wind uplift resistance. An IIBEC article discussing FM Global research documented different failure loads based on the placement of fasteners in insulation boards. The example showed that moving fasteners closer to the board edge increased the tested resistance from 105 pounds per square foot to 160 pounds per square foot.
This illustrates why installation patterns matter. The correct attachment pattern should be based on the requirements of the roofing assembly and the wind loads calculated for the building.
We also need to consider the condition and type of the existing roof deck when working on an existing commercial building. A fastener that performs well in one substrate may not provide the same performance in another.
Roof Perimeters and Corners Need Special Attention
Wind pressure is not distributed evenly across a commercial roof. The field of the roof, perimeter, and corners can experience different design pressures.
The perimeter is particularly important because wind can create greater forces near the edges of a building. Corners can experience even higher localized pressures.
ANSI/SPRI’s wind design methodology specifically separates the roof into different areas when calculating design wind uplift pressures.
This is why a commercial roofing system may require different attachment patterns in different areas of the roof. The fastening pattern used in the center of the roof may not be appropriate along the perimeter or corners.
When we evaluate a commercial roofing project, these differences are important to the overall design. Proper attachment needs to account for the areas of the roof that are exposed to greater wind forces.
The Roof Deck Matters Too
A fastening system is only as strong as the connection between the fastener and the substrate. Before installing a new commercial roofing system, we need to understand what is beneath the existing roof.
Commercial buildings can have different types of roof decks, and their condition can vary significantly. An older building may also have areas where deterioration affects the ability of the deck to securely hold new fasteners.
This is one reason a thorough evaluation is important before a reroofing project begins.
The condition of the existing roof deck is an important factor when determining the appropriate fastening system. Pull tests can help evaluate how well proposed fasteners will hold in the existing substrate.
A pull test can provide useful information about the withdrawal resistance of proposed fasteners in an existing substrate. That information can help the roofing team determine whether the planned attachment method is appropriate for the project.
How Wind Affects Commercial Roofs
Understanding how wind affects commercial roofs is important when selecting and installing a roofing system because wind resistance depends on the performance of the entire assembly.
The membrane may be strong, but the roof still needs secure attachment beneath it. Likewise, strong fasteners cannot compensate for a deteriorated deck or an attachment pattern that does not meet the requirements of the roofing system.
Wind resistance can involve:
- Membrane attachment
- Insulation attachment
- Fastener type and spacing
- Roof deck condition
- Perimeter securement
- Corner securement
- Edge metal
- Flashing and other roof details
ANSI/SPRI’s wind design standard also points to testing standards including ANSI/FM 4474, UL 580, and UL 1897 for determining the wind uplift capacity of roofing assemblies.
The key takeaway for building owners is that wind resistance is an assembly characteristic. A roofing system should be evaluated as a complete system rather than judging individual components separately.
What Does This Mean for a PVC Roofing System?
PVC roofing systems can be mechanically attached, depending on the specific system design and project requirements. The attachment method must follow the roofing manufacturer’s requirements and the design criteria established for the building.
Great Lakes Roofing specializes in Duro-Last roofing systems and has extensive experience installing and maintaining commercial roofing systems. Duro-Last uses custom fabricated membrane sections designed for the specific dimensions of the building, and the manufacturer offers high wind warranties for qualifying systems.
Duro-Last® roofing systems are designed to withstand demanding weather conditions, including high winds and severe storms. Their reinforced membrane and secure attachment methods help the system perform in challenging conditions, making Duro-Last a durable option for commercial buildings exposed to severe weather.
Is Your Commercial Roof Prepared for Wind?
If you are replacing an aging commercial roof or evaluating an existing roofing system, our team can evaluate the roof assembly, deck conditions, and attachment requirements before work begins.
Contact Great Lakes Roofing to discuss your commercial roofing project and determine what attachment approach is appropriate for your building.
Wind Resistance Starts With Proper Installation
A roofing system can be designed to meet specific wind requirements, but the installation still needs to follow the design.
Fastener spacing needs to be accurate. Fasteners need to be properly seated. The correct fasteners need to be used for the substrate. Perimeter and corner attachment needs to follow the project requirements. Other roof components also need to be installed according to the roofing system specifications.
ANSI/SPRI notes that its wind design standard should be used together with the published installation instructions from the roofing system manufacturer or supplier.
This is where contractor experience becomes particularly important. A roofing contractor needs to understand both the roofing system and the conditions of the building where it is being installed.
Great Lakes Roofing focuses on following manufacturer requirements and using appropriate installation practices for each commercial roofing project. Our experience with commercial roofing systems allows us to identify potential challenges before they become installation problems.
What Building Owners Should Ask About Wind Uplift
Building owners do not need to calculate wind pressures or determine fastener spacing themselves. However, asking the right questions can help ensure the roofing project is properly planned.
Before approving a commercial roofing project, ask:
- What wind uplift requirements apply to my building?
- What roofing assembly is being proposed?
- How will the roof be attached to the existing deck?
- Has the condition of the existing deck been evaluated?
- Are pull tests needed?
- Does the attachment pattern change at the perimeter and corners?
- What wind uplift rating does the proposed assembly have?
- Does the installation follow the manufacturer’s requirements?
Getting clear answers before construction begins can help prevent problems later.
Wind Uplift Resistance Should Be Considered Before Installation
Wind is an unavoidable part of a commercial building’s environment, but the roofing system can be designed and installed to withstand the forces it is expected to experience.
The fastening system plays an important role in that process. Fastener selection, spacing, substrate conditions, roof zones, edge details, and installation all contribute to the performance of the completed roofing assembly.
Great Lakes Roofing evaluates these factors as part of the overall commercial roofing process. Whether we are installing a Duro-Last PVC roofing system or completing a metal retrofit, we understand that the roofing assembly needs to be properly designed and securely installed for the building’s conditions.
For building owners, the most important step is to work with a qualified commercial roofing contractor who understands the relationship between the roof system and the building beneath it.
Conclusion
Understanding how wind affects commercial roofs helps building owners recognize why fastening systems deserve careful attention during a roofing project. Wind uplift resistance is not determined by one component. It depends on how the membrane, insulation, fasteners, deck, perimeter, corners, and other roofing details work together.
Great Lakes Roofing takes a complete approach to commercial roofing. We evaluate existing conditions, consider the requirements of the proposed roofing system, and use proper installation practices to help ensure the finished roof is prepared for the conditions it will face.
If your commercial building needs a new PVC roofing system, metal retrofit, repair, or professional evaluation, contact Great Lakes Roofing to discuss your project and determine the right solution for your building.
Frequently Asked Questions
Wind uplift is the upward force created when wind moves around and across a building. It can place stress on the roofing membrane, insulation, fasteners, edge details, and connections between the roofing assembly and the building structure.
Fasteners help secure components of a mechanically attached roofing system to the underlying substrate. Their type, spacing, placement, and connection to the deck all contribute to the performance of the roofing assembly.
No. Fastening patterns can vary depending on the roofing system, building design, substrate, calculated wind pressures, and location on the roof. Perimeter and corner areas may require different attachment than the field of the roof.
Pull tests can help determine the withdrawal resistance of proposed fasteners in an existing substrate. This can provide useful information when selecting an attachment method for a reroofing project.
Yes. The roof deck provides the substrate for many attachment systems. If the deck is deteriorated or unable to provide adequate fastener resistance, the roofing assembly may not perform as intended.
PVC roofing systems can be designed and installed to meet specific wind uplift requirements. The actual performance depends on the complete roofing assembly, attachment method, substrate, design requirements, and installation.
Yes. Wind uplift should be considered during the planning and design stage. Discussing the building’s wind requirements and proposed roofing assembly with a qualified commercial roofing contractor can help ensure the system is appropriate for the project.