Interior glass FAQ

Glass industry representatives answer architects’ top questions
April 3, 2012

FAQs by product 


Can I using a sliding glass door

in lieu of a pivot door?
"Most people want to move away from pivot doors—they don't want to lose the floor space that pivot doors require. Office space is expensive, and owners want to maximize their space. They can do this using sliding glass doors. We look at how many occupants will be in the space to determine if a sliding door can be used, or if a pivot door is required. The local building codes will determine the maximum number of occupants allowed in a space before they have to have emergency egress.
Usually, if owners limit the space to nine occupants or less, they can still have a sliding door." —Brad Thurman, sales and marketing manager, Dorma Glas

How do you lock your doors?
"We are seeing a shift in the market away from glass doors that feature a bottom door rail with a lock at the floor. There is an increase in alternatives, including locking ladder pulls. Fewer folks want to be bent over locking their doors."— Thurman

How much force does it take to slide a frameless door?
"We don't want to require someone be Superman to open and close a door. We manufacture doors that will open with 5 pounds or less of force."
— Paul Witherby, business  development manager, Klein USA

Fire-rated glass

Can I use this hardware
with your door?
"We can accommodate almost any rated hardware package available. However, it may impact the profile of the door."—Tim Nass, vice president of national sales, Safti First

How can we make the interior fire-rated glass match the appearance of the non-rated glass?
"The best way to achieve a uniform glass appearance throughout the building is to specify fire-rated glazing that incorporates float glass. In most cases, the same type of glass specified for the exterior of the building can be incorporated into fire-rated make-ups if that's desired."
— Jeff Griffiths, director of business
development, Safti First 

Why isn't there just one type of
fire-rated glass that will work
for all interior applications?
"There are two different levels of performance required by code. Fire protective products such as safety wired glass, glass ceramics and specialty tempered only have to block smoke and flames. Fire resistive products have to block smoke, flames and deadly radiant heat."—Griffiths

Glass railings

What is the best attachment method for railings?
"There are three basic types of attachment methods: surface mounted to the concrete walking surface; core mounted into a cavity poured into the slab; and fascia mounted onto the leading edge of the floor slab onto the side of stair stringer. The surfacemounted
option has other considerations if a post tension slab is designed onto the project. Strict coordination of post tension cable locations and where the post base plates will be drilled can be of major concern on the project. This usually leads to going with a core-mounted alternative, whereby a block out is left in the concrete to create a cavity where the post can be inserted and grouted into
its final position. Post tension cables can easily be located on either side of these block outs prior to the
concrete being poured on site. The fascia-mounted option typically provides additional useable deck square footage and is more commonly used where there are concerns for water penetration into the slab due to condensation. The best fascia-mounting condition is achieved when utilizing a concrete
embed, like a channel anchor plate, that attaches to the railing systems attach."
— Jim Ellsworth, principal, Custom Components Co.

Movable wall systems

Can I get a means of egress?
"We can provide egress solutions at both the end of the partition and the middle, if desired, with the use of either a pivot panel or a convertible panel. Convertible panels are achieved by utilizing a split rail that will maintain the look and feel of the standard top rail along with the functionality of a typical pivot door."—Scott Ladd, marketing manager, Modernfold Inc. 

What are my size limitations for the glass or opening? 

To determine the largest glass size possible for an interior application, consider building logistics, codes and product type. Building logistics, such as the size of the freight elevator, often present the biggest limiting factor for glass sizes in interior applications. "[Our systems] can accommodate a glass panel that weighs up to almost 400 pounds. However, the issue is how you're going to get it into the building. The size of the glass is determined by logistics, not by the [glazing] systems," says Paul Witherby, business development manager, Klein USA.

Building codes for interior glass vary depending on application. Consider an office entry, where "people often want their glass entries to go 8 feet to 10 feet in height," says Brad Thurman, sales and marketing manager, Dorma Glas. "We look at the situation and the application to consider factors like: how often will the door system be used. From there, we consult the codes. ... Most of the time, office heights are limited to 9 feet, unless you use a glass transom over the door to reach the 10-foot mark."

Codes also closely dictate opening size for protective glass products on the interior, adds Tim Nass, vice president of national sales for Safti First. "Opening size all depends on the
product. [Fire-protective] products have limitations on the amount and overall opening size due to their performance limitations dictated by code. [Fire-resistive] products have no such limitations," he says.

Designers can work with their glass supplier to determine the best glass and opening dimensions given the aesthetic and performance demands. Typically, interior glass panels for Modernfold systems are limited to 300 pounds to 350 pounds, says Scott Ladd, marketing manager. "The taller the opening, the narrower each panel would need to be," he says. "If height is not a concern, but rather you're interested in decreasing the number of panels, or seams between pieces of glass, the use of ½-inch glass allows for wider panels." 

How do I achieve the best acoustical performance? 

The right interior glass systems can achieve sound transmission levels suited to even more sensitive environments, such as law offices. "There are a tremendous amount of products that
can provide soundproofing," Thurman says. "There are laminated glass products and products that are separated by an airspace, for example."

"We have made acoustic panels with glass," says Joseph Jaroff, owner of Jaroff Design & Mison Concepts Inc. "What you get is something totally clear, with the sound transmission
rate the same as insulated drywall."

"Although actual results can vary due to design and building variables, a laminate glass wall using an acoustical interlayer can provide a [Sound Transmission Class] of 39 in a single laminated unit. Using this in combination with an insulated glass unit will result in an even higher STC," says Diane Turnwall, director, interiors, Guardian Industries. According to, an STC of 39 is equal to a solid core wood door—loud talk can be heard but not easily understood.

Designers should also consider the other materials used in the space. "Glass reflects sound, and designers may want to choose other materials, such as ceiling tiles, in the environment to absorb sounds," Witherby says. "Doing this can accomplish some of that acoustical value." 

What new glass options are available? 

"The most common question I get is, 'what's available in the market?'," Jaroff says. New interior glass products are continuously coming to market, offering an ever-growing number of
options to designers. "With glass, we can laminate in fabrics, woods, meshes; we can print on interlayers, and embed lights into glass; and printing on glass is really starting to take off," he says.

"One's imagination is the only limitation to what is possible," Turnwall says.

Industry representatives recommend that architects discuss their performance and aesthetic goals with their glass supplier to determine the best product options. "When it comes to those types of elements, it's important to know the applications, to know how often the space
is going to be used, and, last but not least, to know their budget," Thurman says.

Jaroff adds, "An architect has to be attuned to so many different materials. If they approach me with the aesthetic and program requirements, I can help them with the colors, textures, techniques. We work with designers to find out what they want to achieve. Is this glass going to be in harm's way, or will it be an interior office partition? Do they want translucency, textured glass? We find out what it is they want to achieve within the space, and then we bring out the best options." 

What are my options for visual privacy? 

Privacy is a top concern for owners and designers when dealing with interior glass, particularly when glass is being used in place of more traditional walls. Owners and designers want to capture the lighting benefits of glass, "but limit the sense that occupants are in a fish bowl," Turnwall says.

Based on privacy requirements and budget, the glass industry has numerous solutions, from dynamic products that can shift from clear to opaque to an array of decorative glass products that can obscure views.

Satin-etched, painted, digitally printed and textured products are some examples of privacy solutions. Architects can also look to "laminated products that provide different degrees of opacity and color options," Thurman says. Many designers choose glass that obstructs views of a particular area in a room, such as clear glass with a decorative horizontal band that would block views at desk level, Witherby says.

Architects can get creative with their privacy solutions, Jaroff says. "The whole area of interior glass is really opening up in terms of the range of products available." One glass product targeted toward the privacy market is a laminated product that "makes anything beyond 21
degrees out of focus to a viewer," he says.

Other designers might prefer dynamic solutions. For example, Guardian offers a switchable privacy glass that transitions from transparent to opaque at the flip of a switch, allowing a user to "create privacy when it is needed, but provide daylighting the remainder of the time," Turnwall says. Modernfold offers an alternative dynamic solution with its fully automated
electrically operated blinds integrated within its Moveo panels, Ladd says.