Is a large missile impact window or door automatically approved for small missile impact?

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Overview

Changes to the 2020 Florida Building Code for Porous Impact Protection Devices

Porous Impact Protective Systems:

ASTM E1996-12A brought a significant change to Porous Impact Protective Systems (PIPS). A Porous Impact Protective System is defined as “An assembly whose aggregate open area exceeds 10% of its projected surface area”. Prior to ASTM E1996-12A, any specimen that had passed the Large Missile Test, was not required to pass the Small Missile Test except for shutter assembly’s that contained openings greater than 3/16” projected horizontally. ASTM E1996-12A and forward, requires all Porous Impact Protective Systems to pass the Small Missile Test. It is important to note that all PIPS’s require enhanced separation to glazing requirements while  Non-Porous systems generally have no separation to glazing requirements as they are not protecting the glazing, but protecting the envelope of the structure from rapid internal pressurization.

Engineers, Contractors and Design Professionals must consider the existing glazing when using a Porous Impact Protective System on existing construction. As seen in Hurricane Michael in the Florida Panhandle, some Porous Impact Protective Systems allowed Building Envelope Failure due to the existing Glazing blowing out behind the Porous Impact Protective System (FEMA MAT report). This is not the fault of the PIPS, but of the application over glazing with a lower Design Pressure than current wind design requires for the PIPS. A Porous Impact Protective System works in conjunction with the glazing therefore both have to meet the same required Design Pressure.

The implementation of the 2020 FBC will no longer recognize prior versions of ASTM E1996 prior to E1996-12. This will not require manufacturers to retest, but will require Product Approval Engineers of record to review the standard for compliance. A letter of equivalency submitted with the 2020 approval will suffice. However, all Porous Impact Protective Devices will require at least one Small Missile test performed at a recognized FBC approved Test Lab.

If a product is rated for Large Missile Impact (LMI) and has laminated glass as an infill, then it can be used anywhere in the building provided the product meets the pressures whether large or small missile (large missile level ‘D’).

If the product is Large Missile impact with an insulted laminated glass the single lite, if located on the outside, must be tempered if installed above 30’ to pass small missile impact.  This tempered glass would have to be tested.  If the LMI product wasn’t tested with tempered on the outside it cant be used above 30’.

Testing

TAS Testing requirements for large and small missile impact for a Dade County NOA (notice of acceptance) can be found on their website by clicking here

Small Missile Test

A specimen will fail if the small missile goes through.

When the small missile test is required

When prior to impact the specimen has an opening that a 3/16″ sphere can pass, and this opening is perpendicular to the trajectory of the missiles being shot. Also, it is required for products to be installed above 30 feet in elevation and are not to require any protection device.

All 10 small missiles must be fired at once at the required speed for which only the speed of one has to be measured.

After the large missile test (per above TAS Testing)

The small missile test is performed on the same specimen as used in the large missile test.

The small missiles are aimed at the same area as where the large missile impacted; this being the center of the specimen and 6 inches from one corner. Also, Ordinance 93-141 requires a third small missile impact “distributed uniformly over a two square foot area located at the center of the long dimension of the specimen near the edge”.

 

Requirements for protection of building openings (5th, 6th, Edition of the Florida Building Code)

• Specified on three different maps based on risk category.

• Defines and incorporates the High Velocity Hurricane Zone (HVHZ) consisting of Miami Dade and Broward Counties.

• Defines areas of the state requiring wind-borne debris protection (see ASCE 7-10 wind map).

• Areas within 1 mile of the mean high water line (the average between high and low tide) where the wind speed is 130 mph or greater, or any location where the wind speed is 140 mph or greater.

• Defines wind-borne debris protection.

• Large-missile impact protection for all openings below 30 feet above grade.

• Small-missile impact protection for openings from 30 feet above grade.

Exception – outside HVHZ only:

• Glazing in Risk Category II building located over 60 feet above ground and over 30 feet above aggregate surface roofs located within 1,500 feet of the building shall be permitted to be unprotected.

• Includes a system of product approval.

 

 

Last Update: April 1, 2022  

January 30, 2021  Codes & Standards  
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