Using Wind Clamps to Improve Wind Uplift on Standing Seam Metal Roofs

Among the most important factors to account for when specifying a standing seam metal roof are wind control and wind uplift. It is imperative to take the necessary measures to ensure the safety and efficacy of the metal roof. The wind clamp—an extruded piece of aluminum that is placed on the panel seams at clip locations—is one accessory that can be used to improve wind uplift characteristics on metal roofs, delivering substantial time and cost savings as these devices help mitigate risk of wind uplift and improve overall wind design.

Panel Deflection
Standing Seam Panel Deflection as a Result of Wind Uplift

Why Use a Wind Clamp

A typical failure mode of a standing seam metal roof panel is the clip top pulling out of the panel seam when the panels are subjected to high winds.  With a standard install of a standing seam panel, the seams just fold into each other. With enough pressure, wind will force seams to come apart—be it a vertical failure, horizontal movement of the seam or from clip disengagement. The clip top can then pull out of the panel seam.

The wind clamp resists the panel seam being opened, allowing for higher uplift loads. The purpose of wind clamps, in fact, is to prevent Windclamprszdfailures at the seam openings due to any deflection of the panel. The wind clamps provide more strength, thereby dramatically improving wind uplift performance.

The clamp is installed over the panel seam at clip locations, in the edge and corner zones of the roof.  This allows the roof to resist the higher wind pressures in these zones, usually eliminating the need for additional purlins or joists. On large roofs, the savings can be substantial.

Another benefit is shorter installation time. Since additional purlins or joists are typically not required at the edge or corner zones of the roof, the building can be erected faster.

Choosing Wind Clamps

When choosing the type of wind clamp, it is important to consider the type of panel and the special features of the clamps. MBCI, for example, uses S-5!’s patented wind clamps, which work for two panel types—Ultra-Dek® and Double-Lok®. The S-5! wind clamps do not penetrate the steel, thereby eliminating the risks of corrosion and water leakage that can be introduced by a hole in the steel. Since the screws are hidden from the weather elements, it helps to maintain waterproofing.

Quantitative Difference with Wind Clamps

One of the biggest benefits of using wind clamps in the edge and corner zones is that usage minimizes the quantity of purlins needed, resulting in substantial cost savings. For example, let’s look at a comparison using MBCI’s Double-Lok 24” – 24 ga. panels with and without wind clamps.Chart for blog image

In this example:

  1. The use of wind clamps in the edge and corner zones eliminated 3,800 linear feet of purlins.
  2. Assuming 8” x 2-1/2” Zee 14 ga. purlins were used, there would be a cost savings of $10,400.


Utilizing wind clamps to protect the investment of a standing seam metal roof can increase strength, make installation faster and lower overall cost.

Wind Designs for Metal Roofs

One of the most important requirements for metal roof installation is ensuring that a roof stays in place when the wind blows.  The core concept is that the roof’s wind resistance needs to be greater than the wind loads acting on a building’s roof.  Wind resistance is most commonly determined by a physical test; wind loads are calculated.

Calculating Wind Loads

Wind loads are based on the design wind speed (which is based on the geographic location of the building), height of the roof, exposure category, roof type, enclosure classification and risk category.  The height of the roof, and exposure and risk categories are factors that are used to convert design wind speed to an uplift pressure.  Wind speed maps and the rules to calculate wind pressures are found in Section 1609, Wind Loads, in the 2012 or 2015 IBC.  The information is based on an engineering standard written by The American Society of Civil Engineers, “ASCE 7-10, Minimum Design Loads for Buildings and Other Structures.”Wind Uplift Testing_2

Defining Exposure Risk Category

Exposure categories relate to the characteristics of the ground, such as urban and suburban areas or open terrain with some obstructions or flat areas like open water.  There are 4 risk categories.  Category I is low risk to humans, such as agricultural facilities. Category III includes, for example, buildings for public assembly, colleges and universities, and water treatment facilities.  Category IV includes essential facilities like hospitals and police stations.  Category II is everything else—most roofs are Category II. A building shall be classified as enclosed, open or partially enclosed. The enclosure classification is used to determine the internal pressure coefficients used to calculate design roof pressures.

Determining Wind Pressures

Contractors should work with a structural engineer or the metal panel manufacturer to determine the wind pressures for each roofing project.  Wind pressures are determined for the field of the roof, the perimeters and the corners, where loads are largest.  Only after determining the design pressures can the appropriate metal panel roof system and attachment requirements be designed.

Testing Uplift Resistance

Physical tests are the most common method to determine uplift resistance.  Panel width and profile, metal type and thickness, clip type and frequency, type and number of fasteners, and the roof deck contribute to the uplift resistance of every metal panel roof system.  Metal panel roof systems installed over solid substrates (with concealed clips or through-fastened) can be designed using the following test standards: FM 4471, ASTM E 1592, UL 580, or UL 1897.  Metal panels installed over open framing can be designed using either ASTM E 1592 or FM 4471.  Manufacturers run these tests; uplift resistance data is available for most metal panel roof systems.  Installers can get this data directly from manufacturers or from web-based listing services provided by FM and UL.

Designing a Legal Metal Roof System

Wind loads and wind resistance information is necessary to verify code compliance.  Get it for every project you install!  Using systems that not only have been tested to the correct tests, but using systems that have uplift resistance greater than the design loads is key to a successful installation, and quite frankly, key to installing legal roof systems.

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