Date: 2021-11-01 14:29:00

Credit: diy13/Bigstock

As building codes and architectural-product requirements for hurricane-prone Florida gain wider adoption, AMCA, the international authority on air-system components, clarifies some of the confusion surrounding louver design and application.


Note: This article originally appeared in the 2021 edition of AMCA inmotion magazineIt was updated in April 2024.


By DOUG PETTY; MICHAEL J. BULZOMI; ANTHONY E. JACKSON SR., CSI, CDT, LEED GA; and ERIC SPOSITO, CDT

In August 1992, Hurricane Andrew ripped through South Florida, leaving unprecedented economic devastation in its wake.1 Miami-Dade County was especially hard-hit, leading to an overhaul of local building codes.

Nearly three decades later, the effects of Hurricane Andrew still are being felt, in the form of requirements for architectural products, including louvers. Increasingly, these requirements are being adopted outside of Florida, such as in the Gulf states of Louisiana and Texas and along the Eastern seaboard.

As more and more emphasis has been placed on building resilience in the Florida Building Codes, louver designs and installations have grown more complex. Because of the increased complexity, there often is confusion among designers, specifiers, and owners. As manufacturers, we see it in questions from our customers. In this article, we will provide answers to some of the most frequently asked questions.

Application

The Florida Building Codes contain many caveats concerning the application of severe-duty louvers. Thus, the type of louver that should be used in a given situation is not always immediately clear.

What is the difference between Florida Building Code-approved (also known as Florida product approval [FPA]) and Miami-Dade notice of acceptance (NOA)? Florida Building Code-approved louvers are accepted for use throughout the state of Florida, while Miami-Dade NOA-approved louvers are accepted for use specifically in Miami-Dade and Broward counties. The louvers undergo similar testing; however, while almost all Miami-Dade NOA-approved louvers are Florida Building Code-approved, not all Florida Building Code-approved louvers are Miami-Dade NOA-approved.

Is an impact rating required for all louvers? Not all louvers installed in the state of Florida require an impact rating. A review of Chapter 4, sections 449 (Hospitals), 450 (Nursing Homes), and 453 (State Requirements for Educational Facilities), and Chapter 16 (Structural Design) of 2023 Florida Building Code, Building, Eighth Edition is recommended when attempting to determine if a location and/or a building requires impact resistance.

Must all louvers in Florida be high-velocity-wind-driven-rain-resistant? According to 2023 Florida Building Code, Mechanical, Eighth Edition (Chapter 4, Section 401.5, and Chapter 5, Section 501.3.2), any louver protecting an air-intake opening or an exhaust opening in a structure located in a hurricane-prone region—defined in 2023 Florida Building Code, Building, Eighth Edition (Chapter 2) as: (1) the U.S. Atlantic Ocean or Gulf of Mexico coast where the ultimate design wind speed for Risk Category II buildings (buildings and other structures except those that represent a low hazard to human life in the event of failure, those that represent a substantial hazard to human life in the event of failure, and those designated as essential facilities) is greater than 115 mph (51.4 m/s) or (2) Hawaii, Puerto Rico, Guam, the Virgin Islands, or American Samoa—must comply with ANSI/AMCA Standard 550, Test Method for High Velocity Wind Driven Rain Resistant Louvers.

Do Miami-Dade NOA-approved louvers meet Federal Emergency Management Agency (FEMA) requirements? Unless it was tested in accordance with ICC 500, Standard for the Design and Construction of Storm Shelters, a Miami-Dade NOA-approved louver would not meet FEMA requirements.

The bottom line: When in doubt about the type of severe-duty louver to use, consult the relevant building and mechanical codes.

Installation

Does wall construction (substrate) affect the method of installation of louvers? Yes. Installation hardware and methods vary depending on substrate, louver model, and louver manufacturer. Review the Miami-Dade NOA-approved and/or the Florida Building Code-approved drawings for more information.

Can Florida Building Code-approved or Miami-Dade NOA-approved louvers be glazed into a curtain wall? There is nothing in the Florida Building Code or the Miami-Dade requirements that prohibits such an installation. Whether a louver can be glazed depends on how it was tested and evaluated. Refer to model-specific NOA or FPA documents for allowable installations.

How should a Florida Building Code-approved or a Miami-Dade NOA-approved louver be undersized? The amount of undersizing varies by louver model and manufacturer. Typically, a rough opening size is provided at the point of order, and the manufacturer undersizes the louver accordingly. See the manufacturer’s model-specific catalog/submittal sheet for more information.

The bottom line: While non-severe-duty louvers should be installed per manufacturer installation instructions and/or engineer-of-record and/or installation-contractor requirements, Florida Building Code-approved and Miami-Dade NOA-approved louvers have very specific installation requirements.

AMCA 540 and AMCA 550

What is the difference between Miami-Dade NOA-required Testing Application Standard (TAS) 201, Impact Test Procedures, impact testing and ANSI/AMCA Standard 540, Test Method for Louvers Impacted by Wind Borne Debris, impact testing? The TAS 201 and ANSI/AMCA Standard 540 test protocols are alike in that, to simulate windborne debris, an air-powered cannon is used to fire a 2-in.-by-4-in. (5 cm by 10 cm) piece of timber at a louver test specimen (photos A and B). One key difference, however, makes the ANSI/AMCA Standard 540 test more stringent: In addition to an impact test of the longest unsupported blade span, ANSI/AMCA Standard 540 requires an impact test of the shortest blade span. Typically, impact tests of shortest blade spans are much more difficult to pass than impact tests of longest blade spans.

Does Miami-Dade accept both ANSI/AMCA Standard 540 and ANSI/AMCA Standard 550? Yes. Per the 2020 Florida Building Code, Building, and the 2020 Florida Building Code, Mechanical, both test standards are acceptable to Miami-Dade.

Is a louver that passed ANSI/AMCA Standard 550 watertight? No. Despite ANSI/AMCA Standard 550 being one of the most stringent water-penetration tests a louver can be subjected to, matching TAS 100(A), Test Procedure for Wind and Wind Driven Rain Resistance and/or Increased Windspeed Resistance of Soffit Ventilation Strip and Continuous or Intermittent Ventilation System Installed at the Ridge Area, a louver that receives a passing grade still could allow the penetration of as much as 2 gal. (8 L) of water over the course of the 70-minute test.

The bottom line: ANSI/AMCA Standard 540 and ANSI/AMCA Standard 550 have achieved substantial code and specification penetration. Thus, it is important to understand how they are applied.

Notices of Acceptance

Is a Miami-Dade NOA acceptable in lieu of project-specific calculations outside of Florida? Yes, provided:

  • The client will accept drawings with a Florida professional-engineer stamp.
  • The client will accept drawings based on the Florida Building Codes.
  • The designed wind load shown on the Miami-Dade NOA is sufficient.

What if building condition is not listed in a Miami-Dade NOA? Only the conditions specified in a Miami-Dade NOA are approved for Miami-Dade County. If a condition is not specified, there are two options:

  • If feasible, frame out openings with a substrate material detailed in the Miami-Dade NOA.
  • A project-specific Miami-Dade NOA can be obtained from Miami-Dade County. The Miami-Dade NOA must be signed and sealed by an engineer who is a member of the Florida Board of Professional Engineers. This generally takes a good deal of time and is somewhat costly.

The bottom line: For a louver to be considered Miami-Dade NOA-approved, it must be installed per the Miami-Dade NOA installation documents found on the Miami-Dade product-control website. When there are questions, always refer back to the manufacturer and model-specific Miami-Dade NOA.

Design

What if fewer than the Miami-Dade-approved number of panels (sections) are desired for a large span? Maximum panel size is based on physical testing. If a larger panel is desired, the louver manufacturer will need to retest and revise the Miami-Dade NOA.

Which perform better, vertical-blade units or horizontal-blade units? In the various AMCA water-penetration tests, including ANSI/AMCA Standard 550, vertical-blade units usually outperform horizontal-blade units. The reason is that vertical-blade units have gravity working in their favor. Because of fewer horizontal planes for water to come in contact with, there is less splashing.

How should pressure rating be determined based on wind-speed maps? Though online calculators are available, it is recommended that a professional engineer be engaged to determine proper wind pressure.

Is there a maximum size for Miami-Dade louvers? Miami-Dade does not specify a maximum size. In practice, sizing is limited based on what the manufacturer has tested and subsequently received approval for. Refer to the Miami-Dade NOA for maximum-size details for a specific model.

Does Miami-Dade approve non-rectangularly shaped louvers? Yes, provided the louvers have been tested and the shape and/or construction is included in the manufacturer’s Miami-Dade NOA.

Are there any purely horizontal-blade louvers that are ANSI/AMCA Standard 550 hurricane-resistant? To date, no, but, where building aesthetics are concerned, there are two ways a horizontal-blade appearance and ANSI/AMCA Standard 550 compliance can be achieved:

  • Using a “dual-module,” or “dual-bladed,” louver with horizontal blades in the front and vertical blades in the back (Photo C).
  • Mounting a control damper to the rear of a horizontal louver (Photo D). Note that the damper must be in the closed position to pass the ANSI/AMCA Standard 550 test and, thus, must be closed in the field to be considered ANSI/AMCA Standard 550-compliant.

Conclusion

While determining the type of severe-duty louver to use for a given situation may seem complex, knowing where to look for information and answers helps to alleviate confusion. A review of the Florida Building Codes and product-specific FPA or NOA documents and consultation with the louver manufacturer should yield the information needed to select, specify, and apply the appropriate severe-duty louver.

PHOTO A. A louver undergoes an ANSI/AMCA Standard 540 test.


PHOTO B. A louver following an impact test.


PHOTO C. “Dual-module” louver. Photograph courtesy of Pottorff


PHOTO D. Control damper mounted to the rear of a horizontal louver. Photograph courtesy of Pottorff

Reference

  1. National Park Service. (n.d.). Hurricane Andrew (1992). Retrieved from https://bit.ly/NPS_Hurricane_Andrew

About the Authors

Doug Petty is formerly product manager, louvers and architectural products, for Pottorff; Michael J. Bulzomi is product manager, commercial dampers, for Greenheck; Anthony E. Jackson Sr., CSI, CDT, LEED GA, is product manager for The Airolite Company LLC; and Eric Sposito, CDT, is director, architectural-product solutions, for Construction Specialties.


To Learn More …

For more on severe-duty louvers—specifically, the circumstances under which a severe-duty louver may be needed, testing severe-duty louvers undergo, and criteria a severe-duty louver must meet to be applied appropriately—read “Improving Building Resilience With Severe-Duty Louvers” from the 2019 edition of AMCA inmotion here.