David Vermeulen, the Midwest territory manager for Technical Glass Products, spends a lot of time talking with Building Teams about impact glazing and fire-rated glass. “There’s still a little confusion about the products—on the types of glass available, how they’ve changed over the years, and how they can be used,” he says. “People are surprised by what they can do with fire-rated glass.”
Here Vermeulen shares some back-to-basics answers to seven common questions about impact glazing and fire-rated glass.
1. How does fire-rated glass differ from ordinary glass?
Fire-rated glass has been tested to act as a barrier to the spread of flames and smoke, a practice known as compartmentalization. The framing and glass undergo independent testing from such organizations as Underwriters Laboratories, where a fire is ignited and the temperature (which can be as high as 1,000ºF after only five minutes) is measured on the surface of the glass. Ratings are given based on the length of time the glass remains intact. The test concludes by blasting the heated glass with water from a two-man fire hose to determine the system’s ability to withstand impact pressure and its resistance to thermal water shock. Fire-rated glass ratings range from 20 minutes up to three hours, depending on the product and framing system.
2. When using glass in fire-rated locations, is impact safety glass also required?
No. Building codes determine where impact safety glass is required. “Generally speaking, any glass 18 inches off the floor or 36 inches from a door—and any door glass itself—has to be safety glass,” says Vermeulen. However, a transom over a door would not require the use of impact-rated glass, so a fire-rated glass that is not impact rated could be used and is a less expensive option than glazing offering both impact- and fire resistance.
3. What types of impact glazing are available?
There are two types: Category I and Category II.
Category I represents 150 foot-pounds of impact, which simulates a small child (approximately 85 lb) running into the glass. Glass meeting this test is limited to a maximum size of nine sf per lite.
Category II represents 400 foot-pounds, which simulates an adult running into the glass, and is the highest level of required impact-rated glass. With few exceptions, all tempered or laminated glass in use falls into this category, and any opening over nine sf has to meet category II standards.
4. What types of fire-rated glass are available?
Two types: thin and thick.
Thin glass is approximately 1/4- to 5/16- inch thick and fits into standard fire-rated steel frames. Thin glass is now available in larger sizes than previously offered—allowing greater design flexibility and larger openings for increased daylighting transfer—with fire ratings from 20 to 90 minutes. Thin products are classified as “opening protective” and block smoke and flames, but are not heat barriers. Thin products are available with or without impact ratings.
Thick glass products, commonly called glass walls because they allow virtually unlimited expanses of glass and are typically used in areas where glazing exceeds 25% of the wall area, measure ¾ inch or more in thickness and are tested to the same standards as solid barrier walls. Fire ratings for thick glass range from 45 minutes up to two hours, and the products block smoke and flames as well as heat.
5. Does fire-rated glass limit design possibilities?
No. “Design possibilities have reached new heights, and that’s triggering a change in the way projects are being built,” says Vermeulen. Advances in glass technology and framing materials address limitations on window sizes and allow windows to meet the same code requirements as a firewall. Vermeulen says designers are now able to use fire-rated glass instead of traditional wall construction to bring more natural daylight into the interior. “We even have fire-rated glass floors now,” he says. New labeling that makes it easier for code officials to determine whether or not the proper glass is used in the space will be part of the International Building Code for 2012.
6. Are fire-rated products more expensive?
Fire-rated glass is more expensive than traditional glass, and typically accounts for 2% of a building’s total budget, according to Vermeulen.
7. Is fire-rated glass traditionally an interior product?
Yes, but that’s changing somewhat. “Insulating fire-rated glass for exterior use is a new thing,” says Vermeulen. In general, fire-rated glass is used on a building’s exterior in cases where adjacent buildings are very close to the property line, to keep fire from leaping from one building to the next. BD+C
David Vermeulen has nearly a decade of fire-rated glazing experience, and has successfully worked with code officials, architects, and designers from schematic product development through installation.
Related Stories
| May 23, 2013
Are design-build contracts killing small architecture firms?
Are federal design-build contract laws unfair to small firms? AIA thinks so, citing an interesting fact: an architecture firm spends a median of $260,000 to compete for a design-build project.
| May 23, 2013
Is the 'bring your own device' discussion stumping your IT group?
A new twist to the communication challenge most companies and IT departments face is the “bring your own device,” or BYOD, conundrum. I call it a conundrum because it is stumping many IT professionals.
| May 23, 2013
Portland State University’s School of Architecture launches Center for Public Interest Design
Portland State University’s School of Architecture is proud to announce the launch of its new Center for Public Interest Design, a research center that aims to investigate and utilize the power of design to make social, economic and environmental change in disadvantaged communities worldwide. The Center is the first of its kind in the nation.
| May 22, 2013
Return of retail? Rent growth seen in recovering markets
Like digging a ditch with a spoon, retail demand driven by population growth has eaten away at the supply of available store space in the markets that have been slowest to recover from the downturn. Vacancy rates are reaching a point that will give at least some landlords in every market the clout to demand slightly higher rents.
| May 22, 2013
New ASTM standard enhances hollow structural sections
ASTM A1085 is a big step forward in simplifying HSS design and usage, thereby making it a more desirable option for HSS.
| May 22, 2013
Architecture billings take a step back in April, ending growth streak
For the first time in 10 months, the AIA's Architecture Billings Index slipped into negative territory, falling to 48.6 in April, down from 51.9 the previous month. This is the ABI's lowest mark since July 2012.
| May 21, 2013
Foster + Partners reveals plans for London residential towers
British firm Foster + Partners has unveiled plans for two residential skyscrapers as part of a mixed-use development in north London.
| May 21, 2013
RSMeans cost comparisons: pools, racquetball courts, bowling alleys, hockey/soccer facilities
Construction market analysts from RSMeans offer construction costs per square foot for four building types across 25 metro markets.
| May 21, 2013
7 tile trends for 2013: Touch-sensitive glazes, metallic tones among top styles
Tile of Spain consultant and ceramic tile expert Ryan Fasan presented his "What's Trending in Tile" roundup at the Coverings 2013 show in Atlanta earlier this month. Here's an overview of Fasan's emerging tile trends for 2013.