“Weather The Storm”, with Wind Driven Rain Louvers

Introduces 

“Weather The Storm”, with Wind 

Driven Rain Louvers 

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Learning Objectives 

UUpon completion l ti of f thi this course th the ddesign i professional f i l 

will be able to: 

• Explain what a Louver is 

• List the terms associated with Louvers 

• Explain how louvers are tested and what the new, 

more stringent test methods are 

• Understand how Test Methods influence louver design 

• Review the AMCA International’s standards for louver 

design and testing

Louvers! 

Louvers are applied universally to many building types

Form and 

Function 

Louvers are available in all types of shapes and sizes. Louvers 

provide protection from noise and local weather conditions while 

providing idi outdoor d air i ffor ventilation. 

il i

Form and Function 

Because of their versatility, louvers make excellent choices for air 

intake and air exhaust in and out of buildings. 

Louvers can be located on top of buildings or at ground level. 

8


Louvers can also be part of the design for mechanical rooms. 

9


Or garage and warehouse ventilation. 

10


Louvers can be an integral part of a building’s architecture. 

11


Continuous line designs give architects the flexibility they need. 

12

Here is a Louvered Architectural Mechanical Room Enclosure. It is 4 


stories high, and is another good example of how special architectural 

considerations id i can bbe executed d using i llouvers.


Triangular shapes are very popular designs. 

14


From High g Rise to 

Low Rise, louvers 

are constructed to 

meet the demands 

of the buildings 

atheistic and 

mechanical needs.


Louvers are only limited by your imagination. 

16

Louver Design Considerations 

Wh When ddesigning i i llouvers, consideration id ti should h ld bbe given i tto 

the following five criteria: 

– Airflow 

– Rain Defense 

– Structural Integrity 

– Noise 

– Aesthetics

Airflow / Three Factors 

• Airflow/Volume 

– The measurement of the rate of airflow that passes 

through a louver,(measured in cfm or m3 through a louver,(measured in cfm or m s) 

• Pressure Drop 

– The resistance to airflow across an open louver 

( (stated t t d iin iinches h of f water/Pa) t /P ) 

• Free Area Velocity 

– Rate of airflow that passes through the free area of a 

louver (expressed in fpm/ms)

Airflow 

All Three Factors Depend On The Other Other… 

• Airflow is the amount of air needed to perform the air 

handling ffunctions nctions in the bbuilding. ilding 

• Pressure Drop p can increase or decrease with airflow 

depending on the louver design. 

• Free Area Velocity varies as louver construction varies. 

Closely spaced louver blades generally have lower free 

areas and thus higher free area velocity for a given cfm 

airflow. 

• In Europe, Free Area Velocity is not a generally used 

term. Sometimes jet velocity (meaning the same thing) 

is used, but normally face velocity (air volume divided by 

the core area) is used.

Rain Defense 

• AMCA 500 500-LL is the current louver test standard that 

includes Water Penetration and Wind Driven Rain test 

criteria. 

• Water Penetration Test refers to the test method that 

uses “Still Air.” The velocity at which .01 ounces of 

water passed through the louver louver. 

– No European equivalent to the Water Penetration 

test, only the Wind Driven Test. 

• Wind Driven Rain Tests New to the U.S. test standard 

with wind pressure applied to face of louver. They are 

lloosely l bbased d on EEuropean test standards d d generated d 

by HEVAC. 

• Effectiveness Class is the new water penetration 

classification used for Wind Driven Rain.

Structural Integrity 

• Wi Windloads: dl d 

– American Society of Civil Engineers (ASCE) 

formula 

– British Standard BS6399 formula 

– Hidden or Visible supports pp 

– Effective Wind Speed (mph) 

– Louver panel size 

• Blade Span (Span tables) 

• Intermediate bracing

Structural Integrity 

• The ASCE formula takes into account the basic wind speed 

(mph), importance factor, exposure factor, height above 

ground and any louvers within 10' from corners. Roughly 10% 

of projects have this requirement. 

• In the UK, the British Standard BS6399 formula is used. 

The UK Building Research Establishment developed a 

computer program on disc that calculates the wind load for you 

using the BS formula. The louver company is responsible for 

proper sizing of the louver supports. There is no standard in 

the UK for louver component deflection although most 

manufacturers follow curtain wall standards standards. 

• The louver support system affects the appearance and 

performance p of the louver. The hidden vertical blade support pp 

can ad as much as 6” to the depth of the louver. Wind speeds 

can be determined by local authorities or by local codes. 20 

PSF is the design standard unless otherwise specified. 

• Wind speeds can be determined by local authorities or by 

local codes.

Noise 

• Sound Transmission Loss 

– ASTM E90-99 - Standard Test Method for Laboratory 

MMeasurement t of f Airborne Ai b Sound S d TTransmission i i LLoss of f 

Building Partitions and Elements. 

• Sound Transmission Classification (STC) 

– The STC rating is calculated in accordance with ASTM 

test method E413-87(1999) ( ) Standard Classification for 

Rating Sound Insulation. 

• Free Field Noise Reduction 

– Free Field Noise Reduction is specified in decibels and 

represents the louvers sound reduction in open areas.

Aesthetics 

• Louver Shape 

– Performance difference 

• Finish Type 

– To match building construction elements 

– Flouropolymer p y and Anodize most common 

– Polyester Powder Coat often used in the UK

Finish 

• Mill finish 

• Flouropolymers (Ex., Kynar, Lumiflon) 

– 50% and 70% PVDF 

– Two-Coat and Three-Coat 

– Mica 

• Anodize 

– Clear Anodize (204R1, 215R1) 

– Color Anodize (Brown and black shades) 

• Powdered Coats 

• Prime Coats

Standards and Codes 

With all of the design flexibility of a louver, testing to real 

world conditions becomes a very key task. Louvers must 

not only look good, good but they must perform in various 

elements of nature. 

S h t i ti k th t th l k 

So what organization makes sure that the louvers work as 

required?

AMCA International 

Certified Ratings g Program… g 

• The Certified Ratings Program was developed in response to 

concerns over product performance on the part of buyers buyers, 

specifiers, and users of air movement and air control devices. 

The Certified Ratings Program assures that a product line has 

been tested and rated in conformance with AMCA International’s 

International s 

test standards and rating requirements. A state-of-the-art testing 

laboratory, specifically designed and equipped with the latest 

equipment to carry-out carry out tests in accordance with all of AMCA 

International’s test standards and other international standards, 

supports the program. 

• This product performance information is valuable for making 

product comparisons.


Certified Ratings g Program… g 

• The Certified Ratings Program requires periodic retesting (every 

three years) to verify performance performance. The program also allows for 

challenge testing, which can be initiated by competing 

manufacturers. 

• The AMCA Certified Ratings Program is far more rigorous than 

any program commonly used in the UK. The Building Services 

Research and Information Association (BSRIA) ( ) has developed p 

test standards on behalf of the Heating and Ventilating and Air 

Conditioning Manufacturers Association (HEVAC). However, 

there is no system with the BSRIA/HEVAC program to supply 

performance f information i f ti for f product d t comparisons i nor is i th there 

periodic re-testing. 

Th b tt li i th t AMCA I t ti l’ C tifi d R ti 

• The bottom-line is that AMCA International’s Certified Ratings 

Program helps people make informed decisions on purchasing 

and specifying air movement and air control products.


Licensed Products… 

How do you know the product you specified is 

licensed by y AMCA International? 

There are basically four ways to determine if a product is participating 

in AMCA International’s Certified Ratings Program. They are: 

11. Visit AMCA International International’s s website at www www.amca.org amca org and click on 

Licensed Products. The products are displayed by manufacturers 

or companies and by product type. 

2. Check the manufacturer’s catalog. g All catalogs g containing g 

certified ratings are submitted to AMCA International’s technical 

staff for approval before publication. 

3. Look for the Certified Ratings Seal on the product. 

4. Contact AMCA International’s Certified Ratings Program 

Department by phone (847) 394-0150 or fax (847) 253-0088 or email 

crp@amca.org. 

There is no system for licensed products under the British/European test 

method, but BSRIA Test Reports are issued as supporting documents.

AMCA 

Louver Test Methods 

There are two distinct methods: 

• Water Penetration at “Still Air” conditions 

• Wind Driven Rain conditions 

Each method carries its own certification.

AMCA Standard 500-L 

Tests and Certifies the following: 

• Free Air Velocity through Louver 

• Pressure Drop 

• BBeginning i i PPoint i t of f WWater t 

Penetration 

• Water Rejecting Effectiveness 

• Discharge Loss 

• Leakage (for operable louvers)

Standard 500-L 500 L Louvers 

Three main factors affect Free Area (FA): 

• Blade Angle 

Larger illustration on the 

• Blade Depth 

following slide 

• Blade Overlap 

Blade Angle has the most direct impact on FA 

Oth Other factors f t that th t affect ff t FA: FA 

Size of louver- i.e. A 4' X 4' louver will have a different FA than a 2' X 2' 

louver of the same blade configuration. g The reason for this is that the FA 

includes the frame; the head, sill and jambs- the smaller the louver 

opening the greater percentage of the overall is 'frame"- and therefore 

there is less area through which air can pass. 

Some manufacturers in US and Europe do not use the AMCA method of 

measuring free area and only consider the space between the blades at 

the front front. Therefore Therefore, their free areas are higher than manufacturers who 

follow the AMCA method.

Standard 500-L Louvers 

FFree Area A 

• Measured Clearance 

• Minimum Inside 

Blade to Frame 

• Minimum Inside 

Blade to Blade


• Once a louver size is below 4' 4 X4' X 4 , FA is reduced 

drastically as a proportion of the over all louver area. The 

frame then constitutes a greater percentage of the overall 

area. 

• The converse is also true, with louver FA increasing as 

the louver increases in size and the frame becomes a 

lesser percentage of the overall louver area. 

• All manufacturers publish FA data charts for unit sizes sizes. If 

FA is a major concern, be sure to consult the respective 

manufacturers data chart. 

• Free Area by itself should NEVER be a design criteria. 

The designer must also consider Pressure Drop. The 

chart on the following slide will further explain explain.


Free Area Tables 

By Actual FA 

or % FA 

35


PPressure DDrop 

• Pressure Drop (PD) is a key design 

element for louvers. 

• The more flowing air changes 

direction, as when passing over a 

louver blade and through a louver louver, 

the higher the PD will be. Blade 

design has a direct impact on PD. 

Generally speaking, the more steps, 

nooks, crannies and drainage 

provisions there are on a specific 

blade configuration, g , the higher g the 

PD. 

Figure 5.4 test set up is for air intakes and 5.5 

is for air discharges or exhausts.


Louver specifications frequently reference FA and PD PD. This 

does not take into consideration the key issue of volume of 

air passing through an opening. 

Depth of a louver is a notable issue with regard to PD. A 

deeper louver with a tighter blade spacing configuration and 

less abrupt blade angle reduces PD, but the trade off is cost. 

A deep louver with many blades will cost more than a 

narrower louver with fewer blades. Gradual curved blades 

provide for a lower PD than abruptly changing blades. 

So, there is a give-and-take relationship between louver 

ddesign, i ddepth, h performance, f and d cost.


Although the concept of FA and PD makes sense sense, the prime 

issue of louver sizing should be "how much air do you need 

to move through the louver" and "what is the maximum 

pressure drop you can live with”. 

From this information a louver may be selected and sized to 

meet all important criteria, satisfying the mechanical 

engineer and the design architect. architect The mechanical engineer 

gets his air performance, the design architect gets his 

appearance and water protection. 

Let’s talk a little more about water protection…


54 5.4 Wall W llIIntake k 

Pressure Required to Accelerate Air and Overcome 

Losses due to Blockage and Entrance Conditions


55 5.5 Wall W llDi Discharge h 

Pressure Required to Accelerate Air and Overcome 

Losses due to Blockage and Exit Conditions


WWater Penetration P i or WWater Rejection R j i 

• Two Test Configurations 

• 5.6 Water Penetration for “Still Air” 

• 55.11 11 Water Rejection for Wind Driven Rain 

Th The engineering i i 

community is very familiar 

with figure g 5.6. It is the 

standard to which most 

louvers are specified. 

The new kid on the 

block is 5.11


55.6 6 Water Penetration


Test Conditions 

• 4” per hour rain 

• 1250 fpm max free area velocity 

(approx 14 mph) 

• Weight of water penetration per ft2 free area @ free area velocity



• This photograph of an AMCA still 

air i ttest t chamber h b llets t you bbetter tt 

understand the test. Please note 

that water is released under still 

air i conditions. diti AAnd d cascading di 

down both the “building” face as 

well as in front of the louver. 

With a steady intake of up to 

1250 fpm, measurements are 

taken with regard to pressure 

drop and point of beginning water 

penetration. Using this test a 

louver is rated and certified.



• Remember though, that this test is administered under 

“l “laboratory” b t ” still till air i conditions diti and d makes k no provision i i 

to gauge the louver’s effectiveness when subjected to 

the horizontal, wind driven rain typical of a moderate to 

severe storm. t 

• Drainable blade louvers tested in accordance with 

AMCA Still Air Tests, Tests (not the AMCA Wind Driven Rain 

Water Penetration Test), will entrain some water when 

subjected to storm conditions. This style of louver 

performs better than the standard non non-drainable drainable styles 

for water penetration. Always consider the Wind Driven 

Rain Performance designs when protection from water 

carryover is a must must.

MASTERSPEC – EVALUATIONS 8/93 

“Water-penetration testing measures the weight of water in 

ounces per sq. ft. of louver free area passing from the 

l louver’s ’ exterior t i tto th the iinterior t i at t various i air i iintake t k 

velocities... 

It is important to realize that the test is based on 

still air conditions and simulates the effect of falling rain and 

rain flowing down the wetted surface of a building over a 

louver… 

This test was backed up by the Masterspec in 1993 because it was the best 

the industry had to offer.

MASTERSPEC – EVALUATIONS 8/93 

…While this may provide accurate data for rain conditions 

with only fan-induced air-intake velocities velocities, 

no test currently exists that provides data on louver 

y 

performance during exposure to wind driven rain”

Real Life Conditions 

Severe Storm footage - Real life conditions. Extensive, 

continuous wind-driven wind driven rain rain.

Typical Drainable Louver Shape 

This is a typical 5 6 tested 

This is a typical 5.6 tested 

drainable louver

“Still Still Air” Air Louver in Wind Driven Test 

Here is the same type of typical drainable louver in a wind- 

driven rain test test.

Examples of Wrong Installations 

International Airport: 

Electrical service area for 

the Monorail system shut down/ 

immobilized for days due to Standard louvers 

poor louver selection used where Storm 

Resistant could 

have been. 

Location and performance of the louver is critical to success of the 

building design. 

51

Louver Rain Defense 

• Prevents Damage 

– Minimizes mold in HVAC 

system 

– Critical for Generators, 

Production Plants 

RAIN 

– Electrical switchgear areas 

– Insulation in duct WIND 

• Protects interior finishes & 

contents. 

– Exhibition Halls, Halls 

Warehousing, Museums…


• AMCA standard 500-L-99 

– AMCA revised its standard to include recommendations 

for wind driven rain testing of louvers based on HEVAC 

method. th d 

• Masterspec 2000 

– Includes substantial changes to the advice given when 

selecting louvers. Wind driven rain resistant louvers 

are now recommended for use. 

Products to meet these needs and recommendations 

have been developed p and are increasingly g y specified. p


• New test methods were required to meet the demands of 

the building designs and prevent water intrusion. 

• In real-life storm conditions where Wind Driven Rain is 

commonplace, rainwater penetrates even the highest 

rated louvers tested under the AMCA still air test. 

• IIn response to t this thi serious i problem, bl llouver manufacturers f t 

introduced products specifically engineered to prevent rain 

entry y 

under storm conditions.


• To maintain a standard of comparison within the industry industry, 

AMCA expanded its testing and certification process to 

include the testing of louvers under moderate and severe 

storm conditions. 

• Further, in their 2000 update, Masterspec included 

specific recommendations for the use of “Storm Storm Resistant” Resistant 

louvers anywhere water entry was a concern. 

• Clearly, y, Wind Driven Rain and the Damage g it can cause 

has become a significant factor in both the design and 

testing of louver products.

“Still Still Air” Air vs vs. Wind WindDrivenRainTests 

Driven Rain Tests 

You can visually and descriptively compare the two tests on the 

following slide. 

Basic comparison: 

1. The AMCA Wind Driven Rain test records multiple data points 

at each of 8 ventilation rates, over as a period of 8 hours or 

more per test- while the AMCA still air test tests for only 15 

minutes to determine the beginning point of water penetration. 

penetration 

2. AMCA still air test tests to establish a point of beginning water 

penetration. The AMCA Wind Driven Rain test rates a louver’s 

effectiveness at preventing water from passing through an 

opening at various test conditions. 

3. AMCA still air test has one set of parameters to test a louver. . 

The AMCA Wind Driven Rain test varies the testing parameters 

ventilation rate and air intake velocity) to rate the louver at a 

variety of test points.


Driven Rain Tests


Driven Rain Tests 

AMCA AMCA 

Wind Driven Rain “Still Still Air Air” 

Test Duration 30 minutes (minimum) 15 minutes (minimum) 

Air Intake (fpm) 

Maximum 1250+ 1250 1250 

Minimum No No 

Wind Driven Rain Yes No 

Rain Fall Rate 75mm/hr (3 (3") ) 4"/hr 4/hr 

or 200mm/hr (8”) 

Static Pressure Drop Yes Yes 

Free Area Yes Yes 

Test Points Numerous 4 

Louver Test Size 1mx1m core or 48”x48” 48" X 48" 

Goal Establish louver Establish point p of 

effectiveness by 

varying test conditions penetration 

beginning water 

As you can readily discern, the Wind driven rain test is much more comprehensive 

and provides a more thorough evaluation of the test louver’s louver s performance with 

regard to effectiveness against rain penetration. 

Here is a point by point comparison, BSRIA/HEVAC test standard doesn’t have the 

higher 200mm/hr (8”/hr) rain category.

Video – WindDrivenTest 

Wind Driven Test 

Look at the wind driven rain test in action action.

AMCA 500-L Test- Test - Video 

Wind Driven Rain 

testing at 29 mph 

wind velocity and 3 3” 

of rain per hour 

Water is outside 

where it belongs 

As you can see, virtually all water is denied entry to the building and is 

drained in a controlled manner to the sill pan, where it leaves the louver. 

Remember Remember, with the new test standards it is no longer adequate to 

specify that a manufacturer must have louvers AMCA certified in 

accordance with AMCA 500-L-99. You must now clarify what test criteria 

and tests the louvers must be tested to… 

Still Air or Wind Driven Rain (and if Wind Driven rain, which condition, 

Standard or Extreme)

AMCA 500-L test - Video 

Wind Driven Rain testing at 29 mph wind velocity 

Wind Driven Rain testing at 29 mph wind velocity 

and 3” of rain per hour


• Rejection Effectiveness 

Classes 

A 99% to 100% 

B 95% to 98.9% 

C 94.9% to 80% 

D below 80% 

• 3” rain/29 mph wind 

• 8” rain/50 mph wind 

Four performance classed and two levels of simulated weather 

conditions diti are obtained bt i d with ith his hi test. t t 

Again, no 8” per hour rain/50 mph wind category in the 

BSRIA/HEVAC standard.

LITERRS 

OF WATTER 

PER HOUR H 

30 

25 

20 

15 

10 

5 

0 

RAIN ENTERING YOUR BUILDING 

STANDARD FIXED 

DRAINABLE 

WIND 

DRIVEN 

DRAINABLE 

STANDAARD 

FIXEDD 

Lets Compare!!! 

Volume of water entering a 

4’ X 4’ louver during a onehour 

period. 

Based on Wind Driven Rain 

testing g at 

29 mph wind velocity 

(For comparison purposes 

only) 

28 liters = approx. 

6 1/2 gallons 

Liters entering through a 4' x 4' Louver durin 

As you y can see, , the wind driven 

a one hhour perios. i Li Liters bbased don Wi Wind dDDriv i 

Rain Testing at 29 mph velocity (equal to 

60-90 mph windspeeds in real life storms.) 

rain louvers perform very well in 

stopping water intrusion.


Actual/Theoretical airflow 

• Discharge Loss Classes 

– 1 - .4 and above 

– 2 - .3 to .399 

– 3 - .2 to .299 

– 4 - .199 and below 

• EXAMPLE: A2 up to 2 m/s 

– at least 99% efficient and between .3 & .399 loss at 394 fpm core 

velocity l it ( (maximum) i ) 

Obviously a solid metal plate would have 100% water rejection effectiveness 

as well. But since we’re talking g about getting g g air into the building, g, the AMCA 

standard must also consider the louver’s efficiency in allowing air in. 

The Discharge Loss Coefficient is a comparison of the actual airflow though 

the louver versus the theoretical airflow through an opening the same size as 

th the llouver. Th Theoretical ti l airflow i fl fformula l iis found f d in i AMCA 501. 501 The Th higher hi h the th 

class, the better airflow performance. 

BSRIA/HEVAC Discharge Loss classes are identical.

Louver Evolution: 

Up p to the Test! 

Louver design has evolved as the 

test methods have improved. 

Let’s take a more detailed look at Louver 

esaea oedeaedoo a oue 

Evolution as we focus on the louver’s 

principal function of rain defense.

Louver Evolution and Expansion 

• “Z” Z or “J” J Non-Drainable Blade Louver 

– Good airflow; very little rain defense 

• “K” Non-Drainable Blade Louver 

– Old “stormproof”; average airflow; very little rain 

defense 

• Drainable Louvers 

– Good airflow; some rain defense 

• Wind Driven Rain “Storm Resistant” Louvers 

– Good airflow on vertical blade; moderate airflow on 

horizontal blade; stops most wind driven rain 

• “H “Hurricane” i ” RResistant i t t LLouvers 

– 

– Florida Code Compliant Louvers 

– Moderate airflow; most stringent tests; severe storm 

conditions; missile impact resistance

Non-Drainable Louvers 

Discussing specifics on 

“Z or J” and “K” 

Each Louver: 

Good airflow 

Looks good 

What we have here is your 

• Stop rain entry? 

typical non-drainable blade 

• No! 

llouver. Thi This iis a versatile til DDo not t use if water t entry t 

louver option anywhere 

is a concern 

Good as a screen 

water defense is not a 

concern concern. It has a high free 

area, generally a low 

pressure drop, may be used 

in either mullioned or 

continuous i li line 

configurations, can be used 

Cross 

for custom shapes and can 

section 

be created with a radius. radius 

Further, this louver is often 

inverted and used as a sight 

Non-drainable blade louvers 

screen. 

are readily available in depths 

from 2” to 6”. Other dimensions 

are available and vary by 

manufacturer.

Drainable Louvers 

Drainable Blade Louvers have traditionally Good airflow 

been bee the e workhorse o o se oof the e louver ou e line e in the e Looks good Visible mullions 

U.S. and remain the most widely specified 

louver today. This is because since their 

Rain Entry Improvement 

introduction the louver has performed 

exceptionally well in the AMCA 500 still air test. No Wind Driven 

They also have been presented in the UK and Rain prevention 

Europe as performance louvers because they 

generally do keep more water out. Remember, 

however, that the AMCA 500 still air test is a 

laboratory condition condition, and does not take into 

consideration wind driven rain, present in most 

storms. 

One reason for their excellent test rating is the 

iintroduction t d ti of f a ddrainable i bl hhead, d which hi h stops t 

most of the water running down the face of the 

building from passing through the louver and 

entering the collection chamber. 

Third paragraph, Drainable blade louvers are 

typically used in an exposed mullion condition. 

Blades must supported on a minimum of every 

Generally speaking, if a mullioned 

5 feet of length and have an exposed mullion 

look is desirable, this is a great 

ffor drainage d i every 10 ffeet. t AMCAC AMCA Certified tifi d louver to specify in sheltered areas 

Ratings do not apply to any sections over 10 

such as below grade areaways, or 

feet length. 

anywhere else rain in a still air 

condition is the norm.

Flat 

Hook 

Drainable 

Drainable Louvers 

Double Drain 

High 

Performance 

Recessed Drain 

Here we have several examples of 

flat, non-drainable or “hook”, 

drainable, double drainable, 

high performance, performance and 

recessed drain louver blades. 

Generally speaking, variations 

on the blade profiles shown 

here all are readily y available 

from most manufacturers. 

Selection of one over another is 

typically a function of published 

louver performance and test 

ddata, the h desired d i d aesthetic h i look l k 

including mullions or 

continuous line appearance, 

blade angle and blade spacing. 

KEY DESIGN CONSIDERATIONS: 

• Louver blade shape- (louver Profile) 

• Louver spacing (louver pitch) 

• Visible louver support system 

(visible louver mullions) providing a 

framed appearance 

• Non visible support systems add as 

much as much as 6” to the overall 

depth of a louver but provide 

uninterrupted blade appearance. 

• Overall louver shape 

69

Horizontal Blade Design 


• The most common "look" of a louver is one in which the louver blades 

run horizontally horizontally. In this design we need to ensure the blades are 

adequately supported, either by visible jambs/mullions or, in the case of 

architectural line blades, by concealed blade brace supports fastened 

to vertical channels, channels or both. both 

• Aesthetically, either option is readily attainable, and most 

manufacturers f t offer ff numerous blade bl d profiles fil ddesigned i d ffor either ith visible i ibl 

mullion or architectural line looks. Intervals of vertical support, whether 

visible or concealed, are a factor of engineering based upon the 

established wind load. 

load



• Horizontal blades are either mechanically fastened or welded to jambs 

and mullions mullions, or are supported by blade braces connected to vertical 

channels or angles. Generally speaking, horizontal drainable blade 

louvers should not span more than 10' without a provision for vertical 

drainage drainage. This is to ensure the entrained water is removed from the 

louver blade before it fills the drain, overflows, and returns to the airflow. 

• It iis recommended d d th that t ddesigners i consult lt with ith a manufacturer f t early l iin 

the design process to ensure the desired mullion interval- to match a 

building module for instance- is attainable within the established project 

load requirements 

requirements. 

• Where rain entry is not a concern, continuous line louver blades without 

provision for drainage may be utilized to attain the desired uninterrupted 

linear look.

Hidden 

Mullions 

Horizontal Line Blade Design 

Visible Mullions 

When a continuous line look is desired, a hidden mullion design is preferred. Hidden mullions are 

usually usua y recessed ecessed well e be behind d tthe e louver ou e face ace so as to be inconspicuous co sp cuous oor invisible s b e to tthe e casua casual 

observer. They are generally utilized in “aesthetical” applications. However, due to their design, 

fully recessed mullion systems do not provide downspouts to adequately relieve drainable blades. 

72 

Drainable blade louvers require partially recessed or visible mullions for proper operation.

Vertical Blade Design 

VVertical ti l Blade Bl d Design D i 

• Vertical louvers have the distinction 

of providing a flowing, continuous, 

curtain-like appearance without the 

need for an expressed vertical 

mullion. Thus, the vertical blades 

themselves act as individual 

drains. 

• Since rainwater naturally wants to 

move from the sky to the ground, a 

vertical louver of Storm Resistant 

design is an excellent and 

economical way to provide 

protection from wind driven rain.

Wind Driven Rain Louver Designs 

Wind Driven Rain louver 

design includes: 

– Sophisticated Blade 

Profiles 

– Closely Spaced 

– Vertical and 

Horizontal Blades 

– Increased Depth

Hurricane Louvers 

“Miami-Dade Miami Dade County Approved” 

Approved 

• Hurricane Tests: 

– Water Penetration 

• No System Airflow 

– Building Envelope 

Failure

Hurricane Approval 45 

• Miami Miami-Dade Dade County Approval Still The Best 

• Applications 

– Wet Room 

– Dry Room 

– Open p Room 

– Closed Room 

• Installation Is Part Of Testing Approval

Hurricane Tests 

• Conformance To Florida Code 

• Approved Miami-Dade County 

– TAS100(a) Wind Driven Rain Penetration - Wet/Dry 

– TAS201 Missile Impact - Closed 

– TAS202 St Static ti Ai Air PPressure - OOpen 

– TAS203 Cyclic Air Pressure - Closed

Tests 

TAS 100(A) WIND DRIVEN RAIN 

TEST 

• NO SYSTEM AIRFLOW 

• 15 MINUTES: 35, 70 AND 90 MPH 

WINDS 

• 5 MINUTES: 110 MPH 

• 8.8” PER HOUR RAINFALL 

• ZERO PENETRATION AT 35 & 70 

MPH 

• .05% ALLOWED AT 90 & 110 MPH 

TAS 201 MISSILE IMPACT 

• 9 LB. 2” X 4” PINE BOARD, 7’ TO 9’ 

LONG 

• IMPACT VELOCITY: 34 MPH (50 

FPS) 

• NO MISSILE PENETRATION OR 

COMPONENTS DETACHMENT 

TAS 202 STATIC PRESSURE TAS 203 CYCLIC PRESSURE 

• HIGH STATIC WIND PRESSURE 

RESISTANCE 

• 1/2 AND FULL TEST LOADS (1.5 X 

DESIGN LOAD) ) 

– 100 PSF RATING - TEST 75 & 

150 PSF 

• LOUVER COMPONENT 

DEFLECTION AND ANCHORAGE 

METHOD 

• CYCLIC LOADS TO SIMULATE WIND 

GUSTS 

• PERFORMED AFTER IMPACT TEST 

– 600 CYCLES AT .5 X DESIGN 

LOAD 

– 70 CYCLES AT .6 X DESIGN 

LOAD 

– 1 CYCLE C C AT 1.3 3 X DESIGN S G 

LOAD 

• CYCLES ARE BOTH POS. & NEG. 

• SAME TEST SET-UP AS TAS 202

TAS 201 Test Photos

TAS 202 Test Photos

Important 

• “Miami “Miami-Dade Dade Co County nt Appro Approved” ed” has more than one 

meaning 

– UUsually ll Wi Wind d LLoad d ttested t d (TAS202) 

– Usually Impact tested (TAS201 & TAS203) 

– Sometimes Wind Driven Rain tested (TAS100A) 

Refer back to slide 78 to see the differences in tests.

Learning Objectives 

Th The ddesign i professional f i l will ill now bbe able bl tto: 

• Explain what a Louver is 

• List the terms associated with Louvers 

• Explain how louvers are tested and what the new, 

more stringent test methods are 

• Understand how Test Methods influence louver design 

• Review the AMCA International’s standards for louver 

design and testing

Introduces 

“Weather The Storm”, with Wind 

Driven Rain Louvers 

Sponsored By: Ruskin Company 

Please note: you will need to complete the conclusion 

quiz online at ronblank.com to receive credit 

3900 Dr. Greaves Rd. 

Kansas City, MO 64030 

Phone: 816.761.7476 

Fax: 816 816.765.8955 765 8955 

www.ruskin.com 

Course Number: RAS10A 

An AIA Continuing Education Program 

Credit for this course is 1 AIA/CES HSW Learning Unit

“Weather The Storm”, with Wind Driven Rain Louvers

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