Contractors working in Moline, Rock Island, East Moline, Silvis, Milan, Coal Valley, and other Illinois communities regularly install siding on homes exposed to thunderstorms, straight-line winds, changing pressure, and windborne debris.

Wind performance is often oversimplified during the sales process. Homeowners hear that one panel is “rated for 150 mph” while another is advertised at an even higher speed. Those numbers may be based on valid testing, but they should not be treated as universal guarantees.

The exact product profile, laboratory setup, building height, site exposure, wall location, effective wind area, substrate, fasteners, spacing, and installation method all affect the real specification. Contractors should sell the complete system—not just the largest number printed in the brochure.

Important Wind-Rating Terms

Why Pounds Per Square Foot Matters

Design pressure describes how force is distributed across the wall surface. For example, a rating of 30 psf means the product is rated for 30 pounds of pressure across each square foot under the conditions used to establish that rating.

The total force can become substantial when pressure acts across a large elevation. More importantly, suction is not always uniform. Corners, roof edges, upper stories, and exposed elevations may experience greater demands.

This is why converting a design-pressure rating into a single advertised wind speed can be misleading. The conversion assumes specific building, terrain, wall-zone, height, and effective-area conditions that may not match the actual project.

What Determines the Required Wind-Load Rating?

VSI Certification and ASTM Standards

The VSI Product Certification Program, now administered through the Polymeric Exterior Products Association, uses independent third-party verification to confirm that listed products comply with applicable ASTM requirements.

Certification establishes a credible minimum level of product evaluation. It does not mean every certified panel has the same wind-load rating or can be installed with the same fastening schedule.

Why Sequoia Select Is a Strong Wind-Focused Option

Sequoia Select is more than a thicker panel. Gentek combines several features intended to strengthen the complete siding system.

Thickness contributes to performance, but it is not the entire wind story. The nailing hem, lock, profile geometry, fasteners, wall support, and installation method work as a system.

Installation Controls Whether the Rating Means Anything

A high-rated siding panel can underperform when installed incorrectly. Wind-load testing assumes the product is attached according to the tested or specified method.

Critical wind-performance details include:

• Use the exact fastener type, length, shank, and head diameter specified by the manufacturer.
• Maintain the required fastener spacing for the product and wind condition.
• Achieve the required penetration into approved nailable material.
• Center fasteners in applicable nailing slots.
• Do not drive fasteners tightly against the vinyl nailing hem.
• Fully engage each panel lock without stretching the siding upward.
• Use a starter strip compatible with the siding’s lock design.
• Keep starter strips level, secure, and continuous where required.
• Verify sheathing and substrate condition before covering the wall.
• Follow enhanced fastening instructions when project conditions require them.

Why Wall Corners Deserve More Attention

Wind accelerates and changes direction as it moves around a building. Wall corners can experience higher suction than the central field of an elevation.

A product that meets the pressure requirement in the center of the wall still needs to be evaluated for the project’s more demanding corner zones. This is one reason a single wind-speed claim cannot replace a project-specific design-pressure check.

Contractors should also examine outside corner posts, J-channels, starter strips, soffit, fascia, and other accessories. The main siding panel is only one component of the exterior system.

Installing Vinyl Siding Over Foam Sheathing

Energy-code assemblies increasingly include continuous foam sheathing. Contractors cannot assume the same fastening approach used over wood-based structural sheathing will automatically apply.

The siding fasteners may need to pass through the foam and penetrate approved nailable material by the required amount. Foam thickness, structural sheathing, framing location, fastener length, and manufacturer instructions must all be considered.

Both the siding’s wind-load rating and the wall assembly must be properly specified. When the prescriptive requirements are unclear, consult the manufacturer, local building official, design professional, or applicable code-compliance documentation.

Wind-Rating Checklist for Illinois Contractors

1. 1

   Identify the adopted code and local amendments for the project jurisdiction.

2. 2

   Determine the required design pressure for the building and wall zones.

3. 3

   Select the exact manufacturer, product line, and profile.

4. 4

   Obtain the product certification listing and published design-pressure rating.

5. 5

   Verify the approved sheathing, substrate, fasteners, spacing, and penetration.

6. 6

   Confirm compatible starter strips, corner posts, channels, soffit, and accessories.

7. 7

   Train the crew on the project-specific installation requirements.

8. 8

   Document product labels, cartons, installation details, and completed elevations.

Common Wind-Rating Mistakes

• Quoting only the brochure’s mph number: This ignores the design pressure and the assumptions used to convert pressure into an approximate speed.
• Assuming every profile has the same rating: Wind-load performance can vary by panel and profile design.
• Using whatever fastener is already on the truck: Fastener head size, length, penetration, corrosion resistance, and spacing can affect performance.
• Nailing tightly: Vinyl must remain free to move with temperature changes.
• Ignoring the starter strip: An incompatible or poorly attached starter strip can allow the bottom course to disengage.
• Ignoring soffit: Soffit and accessories may require their own support, rating, and installation details.
• Assuming local requirements are identical statewide: Verify the code and amendments enforced by the Illinois jurisdiction responsible for the project.

Our Practical Recommendation

Use advertised wind speed as a starting point—not the final specification. Determine the project’s required design pressure and compare it with the rating for the exact siding profile and installation method.

Gentek Sequoia Select is a strong premium option because it combines a .046-inch nominal panel, full-roll nailing hem, Advantage Lock system, ASTM D3679 certification, and negative wind-load testing under ASTM D5206.

The rating only has value when the product is correctly selected and the field installation follows the specified substrate, fastener, spacing, penetration, starter-strip, lock-engagement, and accessory requirements.