FAQs

The term “monolithic glass” describes a single sheet of architectural glass. The term does not apply to laminated glass, which is a sandwich of two or more sheets of glass.

Float glass is formed by “floating” a ribbon of molten glass over a pool of molten tin. Float glass manufacturing is a highly-automated 24-hour operation, capable of producing up to 800 tons of glass per day.

Float glass features uniform thickness and very smooth, glossy, “fire-polished” surfaces – a result of the exposure to intense heat during the manufacturing process. It is nearly colorless with a slight greenish-blue cast, observable through its edge. The visible light transmittance of float glass typically ranges from 75% to 92%, depending on the glass thickness and whether it is regular or low-iron (optically clear) glass.

The quality standards for float glass are defined by ASTM C 1036 – Standard Specification for Flat Glass.

Low-iron glass is also referred to as “optically-clear” glass. It features superior, near-colorless clarity and brilliance. The visible light transmittance of low-iron glass can reach 92%, and depends on the quality of the glass, as well as thickness.

Low-iron glass is excellent for back-painted, color-fritted, and color-laminated glass applications, because it renders the truest colors.

Low-iron glass requires special production using raw materials with naturally low levels of iron oxide.

Colored glass contains metal oxides added to the raw glass batch create glass with color extending through its mass. For example, cobalt produces blue glass, chromium – green, silver – yellow, and gold – pink. Visible light transmittance of colored glass varies from 14% to 85%, depending on the hue and thickness. Typical float glass colors include amber, bronze, gray, blue, and green. In addition, Bendheim offers an almost unlimited palette of specialty colors in rolled and mouth-blown glasses. Our exclusive line of Lamberts art glass offers a rich, unique aesthetic in a palette of over 500 hues.

“Rolled” glass is also known as “machine rolled,” “textured,” “patterned,” and “figured” glass. It is a type of flat architectural glass, manufactured by imprinting a ribbon of glass with a pair of machined or engraved forming rolls. The rolls impress their surface pattern into the glass surfaces. The result is glass with a distinct pattern impressed on one or both of its surfaces.

Bendheim offers hundreds of in-stock textured (rolled) glass varieties, available in standard thicknesses as well as “heavy” thicknesses ranging approx. 3/8″ (10 mm) to 1/2″ (12 mm).

The quality standards for machine rolled glass are defined by ASTM C 1036 – Standard Specification for Flat Glass.

Back-painted glass is a painted glass for applications such as wall cladding elevator interiors, backsplashes, and counter tops. Back-painted glass can be tempered or laminated.

Bendheim’s back-painting process utilizes specialty water-based paints to create an environmentally-friendly, safe, enduring, and VOC-free product for improved indoor air quality. Bendheim’s back-painting capabilities allow for unlimited color options, including precision color matching.

Acid etched glass is exposed to hydrofluoric acid in order to etch a silky frosted surface – not to be confused with sand-blasted glass. Etched glass diffuses transmitted light and reduces glare, making it an outstanding daylighting material. It is maintenance friendly, resisting permanent stains from water and fingerprints. Unlike sandblasted glass, etched glass can be used in demanding applications such as shower enclosures and building exteriors. Should there be any requirement to apply adhesives, markers, oil or grease to the etched surface, testing must be done to ensure removal is possible. Bendheim is proud to partner exclusively with eco-sensitive North American and European etch glass manufacturers.

Sandblasted glass is produced by bombarding the glass surface with small hard particles to create a frosted aesthetic. Sandblasting can weaken the glass and creates a surface prone to permanent staining. Maintenance-friendly etched glass has replaced most sand-blasted glass as the industry standard for frosted glass.

Wired glass is a type of glass with wire strands embedded near to the center of its thickness. It breaks more easily than non-wired glass of the same thickness, therefore it is not a safety glass. Wired glass may be laminated for safety, or have a safety film applied to it, but it cannot be tempered.

Bent glass is a flat glass that has been heated to 1,000° – 1,100° F and gravity – or mechanically-formed into a desired shape.

Heat absorbing glass is a glass (usually tinted) formulated to absorb an appreciable portion of solar energy.

Cullet is recycled glass breakage added to the raw batch in most glass-making operations. With 25% to 40% post-consumer and 20% pre-consumer content, Bendheim’s Lamberts® channel glass and textured EcoGlass™ varieties contain the industry’s highest percentages of glass reclaimed from the municipal waste stream.

Bendheim’s vertically-integrated production facilities and skilled workers fully fabricate specialty architectural glass to the client’s specification, within the standard glass industry tolerances. In-house processes include: cutting, polishing, carving, back-painting, tempering, and several types of lamination. Learn about our capabilities here: bendheim.com/capabilities.

MANUFACTURING TOLERANCES

Cutting:

• For 1/8” (3 mm) to 1/4” (6 mm) thick glass = +/-1/16” (+/-1.5 mm)
• For 3/8” (10 mm) to 3/4” (19 mm) thick glass = +/-1/8” (+/-3 mm)
• For patterns & shapes of any glass thickness = +/-1/8” (+/-3 mm)

Edgework:

• Minimum thickness = 5/32” (4 mm)
• Minimum piece size = 2.5” x 2.5” (64 mm x 64 mm)
• Minimum Width to Height ratio of the piece = 1 to 10

Hole Drilling & Notching:

• Placement tolerances for 1/8” (3 mm) to 1/4” (6 mm) thick glass = +/-1/16” (+/-1.5 mm)
• Placement tolerances for 3/8” (10 mm) to 3/4” (19 mm) thick glass = +/-1/8” (+/-3 mm)
• Minimum radius for cut-outs and corners = the thickness of the glass
• Minimum diameter of holes for tempered glass only = 1/4” (6 mm) or the thickness of the glass, whichever is greater

Hole Location for Tempered Glass Only:

Tempering:

• Min. thickness = 5/32” (4 mm)
• Max. size for 5/32” (4 mm) thickness = 20 sq. ft.
• Max. size for 3/16” (5 mm) or greater thickness = 69” x 145” (1.75 m x 3.68 m)
• Min. diagonal dimension = 9” (229 mm)

Lamination:

• Max. size = 72” x 130” (1.83 m x 3.3 m)
• Min. size = 1” x 1” (25 mm x 25 mm)

Fabrication Drawings:

When drawings are required to highlight specific fabrication details, please submit clear and detailed sketches, complete with all required information, i.e., hole & notch location, radius, etc. Every drawing submitted should be labeled with the corresponding Bendheim order number to ensure proper fabrication.

Custom Waterjet-Cut & Engraved Glass:

Please provide the required specialty font(s) and artwork in Windows TrueType format for fonts, vector files for graphics.

Custom Color Back-Painted Glass:

Color matching within 0.05 tolerance

Glass industry standards regarding visible defects are set by ASTM International.* Understanding ASTM inspection criteria is very important, before identifying and pointing out defects and imperfections. The criteria outline inspection distance, lighting requirements, inspection times, etc. The official ASTM standards are quite long and can be difficult to follow, therefore we are providing this brief summary of the visual inspection criteria, as well as how to determine if a defect is allowable or if the glass may be rejected:

• Glass shall be inspected in the central area: in transmission at a distance of 5 feet from the observer, and in reflection at a distance of 10 ft. from the observer. Note: Bendheim’s inspection standard is always from 5 feet.
• Glass shall be inspected in the border area in transmission and reflection at a distance of 10 ft. from the observer.
• Glass must be inspected using a viewing angle of 90 degrees from the glass with suitable background light.
• Inspection should not exceed viewing of more than 5 seconds for lites up to 6 sq. ft., 10 seconds for lites up to 35 sq. ft., and 20 seconds for lites larger than 35 sq. ft., either in transmission or reflection.
• If defects are visible beyond what is allowable — as outlined in the table below — using the above inspection criteria, the glass may be subject to rejection.

* For these visible defects: no more than 1 total defect is allowed per lite up to 6 square feet; no more than 2 total defects are allowed per lites 6 to 35 square feet; no more than 3 total defects are allowed per lite over 35 square feet. These standards do not apply to hand-made products. Variations in texture, thickness, color, as well as the presence of visible scuffs, scratches, and random small and large (“ox eye”) bubbles are typical in mouth-blown glass and are not considered defects, but rather desirable “perfectly imperfect” characteristics that attest to its authentic hand-made nature.

For more information, please see Bendheim’s ASTM Glass Standards For A&D Professionals, Contractors, and Clients.

Glass is a relatively heavy material. Glazing large openings often requires thicker & heavier glass to minimize deflection and withstand the imposed wind loads. A notable exception is channel glass, which can achieve greater spans in relatively lightweight 1/4″ (6 – 7 mm) thickness thanks to its unique U-shape.

Thicker glass may also provide additional aesthetic advantages, including lending a greater sense of depth and body to the wall. Naturally, the thicker the glass, the greater its weight:

Fire resistance rating is the period of time a building assembly maintains its ability to confine a fire and continues to perform its structural function, as determined by testing.

Fire protection rating typically means the period of time a protective glass assembly maintains its ability to confine a fire, as determined by testing.

Deflection is the amount of glass panel bending, perpendicular to its surface plane, under an applied load.

A neutral cure silicone is a special adhesive used in glass wall-cladding installation. It is durable, flexible, and bonds to most substrates without priming. When cured, it resists moisture, UV light, and high temperatures.

Mirror mastic is a high-performance adhesive for mounting glass mirrors to various interior surfaces, including wood, drywall, metal and painted surfaces. It is flexible and will not become brittle over time. Mirror mastic is easily applied with a caulk-gun, and provides a strong and permanent bond to most types of mirrors.

Annealing is the controlled cooling of glass during the manufacturing process. It is the first level of architectural glass production. The process prevents residual stress in the glass, allowing it to be easily handled and processed.

Annealed glass is not as strong as tempered or heat-strengthened glass of the same thickness, and breaks into large shards. It is not safety glass.

Safety glass is tempered glass (also referred to as “toughened” or “fully tempered” glass) and/or laminated glass that meets the requirements for ANSI Z97.1 and the federal safety standard CPSC 16 CFR Part 1201 (Consumer Product Safety Commission Safety Standard for Architectural Glazing Materials).

Glass is a breakable material. If it breaks into sharp pieces, or shards, it can injure people and pets. Safety glass improves occupant safety and well-being by significantly reducing this risk. In the case of tempered glass, if broken, it exhibits a characteristic “dice” break pattern of many small pieces that minimize the risk of injury. In the case of laminated glass, if broken, it remains in place, held together by the plastic or resin interlayer at its core.

Safety glass is typically identifiable through a permanent marking (a safety seal), generally located in one of the corners of the glass piece. This marking cannot be removed without damaging or breaking the glass.

The US standards for testing and classifying safety glazing materials are:

• ANSI Z97.1 (American National Standards Institute’s Standard for Safety Glazing Materials Used in Buildings)
• CPSC 16CFR, Part 1201 (Consumer Product Safety Commission Safety Standard for Architectural Glazing Materials)

The Consumer Products Safety Commission establishes the federal standards and requirements for safety architectural glass. Federal safety glazing law requires the use of safety glass in defined hazardous locations, designated by the Model Building Codes. Generally, these include:

• Bath and shower enclosures
• All doors, including storm doors, sliding doors, and combination doors
• Sidelites, including and any glazing next to a door or an opening for human passage, if the nearest exposed edge is within 24” (0.6 m) of the vertical edge of the door or the bottom exposed edge is less than 60” (1.5 m) above the walking surface
• Areas where the glass is adjacent to walking surfaces and the bottom edge of the glass is within 18” of the floor
• Areas where the top edge of the glass is more than 36” above the floor
• Glazed panels greater than 9 ft.² (0.8 m²)

Local building code authorities may have additional safety glazing requirements, which can vary by state, county, city, town, or borough. Because each state has either adopted the model federal safety building code, modified it in some sections, or written completely new sections, it is imperative to be guided by the particular state or local building code where the glass is to be installed. For detailed information, please contact your local code officials.

Laminated glass is a safety glass that contains two or more glass lites permanently bonded together with one or more PVB, EVA, or liquid resin interlayers. It meets the requirements for ANSI Z97.1 and/or CPSC 16 CFR 1201, and is typically labeled with a “safety” logo identifying the fabricator, glass type, and the standard it meets. Additional benefits of laminated glass can include improved UV and sound control. Various decorative laminates, including virtually unlimited custom color and interlayer options, are available from Bendheim.

Tempered glass is also referred to as “toughened” or “fully tempered” glass. It is heat-treated safety glass with a minimum surface compression of 10,000 psi or a minimum edge compression of 9,700 psi. The surface of tempered glass is approximately four times stronger than the surface of regular annealed (non-safety) glass of the same thickness.

When broken, tempered glass shatters into small, relatively harmless pieces. This characteristic “dice” break pattern minimizes the risk of serious injury.

Bendheim tempered glass meets the requirements for ANSI Z97.1 and/or CPSC 16 CFR 1201, and is typically labeled with a “safety” logo identifying the fabricator (Bendheim), glass type, and the standard it meets.

Bendheim’s tempered channel glass is SGCC-certified and has a “safety” logo permanently etched into the glass, in compliance with federal regulations. The Safety Glazing Certification Council (SGCC) is the largest independent third-party that inspects and test tempered glass to confirm the manufacturing process and result. The SGCC is a voluntary organization. Satisfactory participation in the Council allows the glass manufacturer/fabricator to etch the SGCC logo permanently onto the glass, as notification that the glass has been properly produced.

Tempered glass is required as safety glazing in “hazardous” applications, such as floor-to-ceiling partition walls, entrance doors, sidelites, etc.

Glass cannot be further processed (cut, drilled,etc.) after tempering.

Heat-strengthened glass is non-safety glass. It is approximately two times stronger than regular annealed glass of the same thickness. It features a surface compression between 3,500 and 7,500 psi and an edge compression of 5,500 psi or greater. Heat-strengthened glass’ break pattern is similar to annealed glass.

Heat-strengthened glass is available from Bendheim for special applications that do not require the use of safety glass.

The term “heat treated glass”  can be used for both tempered (safety) glass and heat-strengthened (non-safety) glass.

The heat soak test or heat soak process is used to minimize the risk of spontaneous breakages of heat-treated glass caused by nickel sulfide inclusions. In this process, glass channels are placed inside a chamber and subjected to an oven temperature of 550°F (287°C) to accelerate nickel sulfide expansion. This causes glasses containing nickel sulfide inclusions to break in the heat soak chamber, thus reducing the risk of potential field breakages. The full heat soak process involves testing all glass in the order, virtually eliminating any chance of nickel sulfide breakage.

Heat soak testing is recommended for all tempered glasses destined for exterior applications subject to changing temperatures. It is normally not required for interior applications.

Chemically strengthened glass is strengthened by chemical ion-exchange and is considered a non-safety glass. Its surface can be six to eight times stronger than the surface of standard annealed glass of the same thickness; however, it exhibits the same break pattern as annealed glass which creates a greater risk of severe injury.

Bullet resistant glass is multiple-laminated glass or glass and plastic designed to resist penetration from medium- to super-power small arms and high-power rifles.

“Glazing” is the installation and weather-sealing of a glass product in a prepared opening.

Double glazing is any use of two thicknesses of glass, separated by an air space, within an opening, to improve insulation against heat transfer and/or sound transmission. In factory-made double glazed window units, the air between the glass sheets is thoroughly dried and the space is sealed airtight, eliminating possible condensation and providing superior insulating properties.

Butt glazing is an installation where the glass is retained at the head and sill, with no structural support on the vertical edges. The vertical joints between the glass lites are typically weather-sealed with silicone. Butt glazed applications may feature exposed edges, often requiring a glass edge specification.

Sloped glazing is a glass installation at a slope of 15 degrees or more from the vertical. It is often subject to greater solar energy exposure and is more susceptible to impact from falling objects, windborne debris, and snow loads than vertical glazing, requiring the use of heat-treated & laminated glass.

Structural silicone glazing is a system where the glass is bonded to the framing members of a curtain wall using a structural silicone adhesive without the presence of exterior retainers or stops.

Fenestration includes any glazed panel, door, window, skylight, or curtain wall unit on the exterior of a building.

Bird-safe glass features a wide range of aesthetic options and manufacturing techniques that deliver the following bird-friendly characteristics:

– A surface texture that breaks up continuous reflections, minimizing or eliminating the “mirror” glass effect (see textured glass, channel glass, and etched glass)
– A bird-safe pattern or design that conforms to the 2″x4″ or Canada’s 2″x2″ rule – more on that below (see fritted glass, etched glass, and digitally printed glass)
– A combination of the two

Why It’s Important

Accidental collisions with glass in buildings are the second leading cause of bird fatalities in North America. According to the American Bird Conservancy, the death toll reaches over a billion birds a year, threatening our biodiversity and ecosystem. Local and state governments have taken note, and are now enacting legislation to require the use of bird protection glass for new construction and major renovation projects. Thankfully, numerous sustainable and affordable solutions are at the ready in the form of multiple varieties of bird-safe / bird-friendly glass.

Glass Reflectivity and Bird Safety

One of the main reasons birds accidentally collide with architectural glass is because they simply don’t understand reflections. To them, instead of appearing as a solid obstacle, reflective glass facades and windows often appear as an extension of the natural habitat – open skies or sheltering vegetation. A proof that glass reflections are one of the leading causes of bird collisions is that the highest rate of avian fatalities occur in the morning, when building facade  reflectivity is at its peak (the sharper the angle of light, the more reflective the glass surface). This also coincides with the time of day when birds are most active.

Avoiding highly reflective, coated architectural glass varieties is the first step towards bird-friendly architecture. To further reduce the risk of bird collisions, architects and designers can specify architectural glass featuring a surface texture that proactively breaks up continuous reflections, signaling to birds that there is an obstacle on their flight path.

Bird-Safe Textured Glass / Channel Glass

Bendheim offers a wide variety of clear and ultra-clear (low-iron) textured glass designs that are effective bird-safe solutions.

Our most popular textured glass for exterior applications is the three-dimensional, U-shaped Lamberts® channel glass. It is exceptionally well-suited for facades due to its ability to build expansive glass walls, including curves and glass-to-glass corners, featuring minimal vertical framing. It is available in a range of light-diffusing, reflection minimizing surface textures, as well as a “clear” (Clarissimo™) pattern designed to maximize views.

Bird-Smart Glass Testing

Curious about the bird-safety performance of our Clarissimo™ channel glass, we tested it with the help of the American Bird Conservancy (ABC) at the Powdermill Nature Reserve in Pennsylvania. The flight tunnel testing determined that even in its clearest form, channel glass presents an effective bird protection. Please see this video for more information on ABC’s testing and Bird-Smart certification for glass.

Among the key benefits of textured / channel glass is the ability to provide occupants the desired level of visual privacy, while enhancing the daylight potential of the building. Textured glass diffuses light, filtering a higher-qualify daylight into the interior that regular clear glass. We are yet to see secondary daylight control devices being used when the building exterior is made of our Lamberts® channel glass.

Another eco-forward benefit of Lamberts channel glass is its low-carbon footprint, thanks to the use or renewable energy and a high percentage of recycled content (as much as 40% post-consumer). Please see our channel glass’ environmental product declaration (EPD) for more information.

Bird-Safe Glass Patterns | The “2×4” / “2×2” Rule

Birds are experts at navigating dense green vegetation, finding small openings through twisted tree branches. They even successfully avoid flying through obstacles as delicate and subtle as spider webs. The principle behind bird-friendly glass patterns is using this sensitivity to make even highly see-through glass “visible” to birds.

The “2×4” bird-safe rule is based on testing, and presents an easy to follow formula to choose an effective bird protection glass solution, or create an effective customized pattern. Essentially, it stipulates that horizontal design elements (i.e. lines or dots) should be spaced no more than 2” from each other. Vertical design elements should be spaced no more than 4” apart. Canada’s stricter standard recommends both horizontal and vertical design elements to be spaced no more than 2” apart.

A variety of Bendheim decorative glass types can be selected in the 2″ x 2″ rule for bird protection applications, including etched glass, decorative laminated glass, digitally printed glass, and pattern frit glass.

Bendheim’s SatinTech® etched glass is a great, time-tested glass solution. Its satin-smooth matte finish is achieved through chemical etching. The process creates microscopic “peaks and valleys” in the surface of the glass, which are so miniature they don’t trap oils and dirt the way sandblasted / particle blasted glass can. Etching can cover the entire glass surface, fully obscuring views and diffusing the light, or can be patterned, where the design is applied through a “printing” screen. Patterns can range in openness, offering various degrees of obscuration. Linear patterns tend to be very popular due to their timeless appeal, but more non-traditional “organic” patterns are a great way to highlight the facade and give it a distinct visual identity.

Decorative laminated glass can be used to insert a variety of exterior-appropriate decorative interlayers, filters, or digital prints into the glass. Prints in particular are becoming an increasingly popular option, thanks to their ability to create photo-realistic mural facades, or to add custom logo elements to the facade. High-resolution digital images or scalable vector graphics are imprinted onto specialized clear filters, and then laminated between two lites of low-iron glass. The near-colorless low-iron glass renders truer colors in comparison with regular glass, which features a distinctive bluish-green tint.

Digitally printed images can also be produced through the “direct-to-glass” printing technique. Special frit-based paints are used to apply the design to the glass, and are then fired onto the glass at high temperatures. The resulting product is safety tempered (heat strengthened).

Decorative frit glass is among the most popular options to create customized bird-friendly glass designs for exterior applications, due to its durability, ease of customization, large panel sizes, and cost-effectiveness. Pulverized, powdered glass colors (frits) are applied to the glass surface using a printing screen to create the desired designs. The glass is then heat treated (tempered) to “seal” the frit.

Thanks to their exceptional durability against the elements, frit glass designs can be applied to any of the glass surfaces, including the outermost Surface #1.

Surface #1 Frit Glass: Most Effective Bird-Safe Glass

Bendheim’s Lumi Frit surface #1 glass is an exceptionally effective bird protection option, because it simultaneously incorporates the 2″ x 2″ rule and breaks up continuous reflections by wearing its pattern on the outermost (most reflective) glass surface.

Bird protection is not the only design benefit of this type of glass. In the Johnson Community College example above, our Lumi Frit surface #1 pattern was applied primarily to create an ultra-white glass facade aesthetic in a north-facing location that would normally be cast in the shadow of the building. Rather than appearing dark and downcast, our white fritted low-iron glass creates a brilliant, luminous facade, as daylight reflects off its dot-fritted surface. Fritted glass also provides a solar shading benefit, reducing the solar heat gain and improving the energy efficiency of the glass facade.

Effective Bird Protection

Textured, etched, fritted, and digitally printed glass varieties meeting the 2″ x 2″ bird-friendly rule are all proven, effective solutions for avian-safe glass buildings. In addition to helping avoid collisions, these decorative architectural glass varieties present the opportunity to lend a unique aesthetic to the building and enhance its design, privacy, and daylighting potential.

New York City’s Jacob Javits Convention Center, for example, used to be one of the deadliest structures for birds prior to its renovation by FXCollaborative. Bird safe glass featuring a subtle dot frit pattern replaced the offending mirrored glass throughout the facade. The new patterned glass appears transparent, but has been shown to reduce bird collisions by as much as 95%. For more information, see “How Architects Are Designing Buildings With Birds in Mind,” Architectural Digest, https://www.architecturaldigest.com/story/how-architects-designing-buildings-birds-mind.

Ineffective Bird Protection

Bird decals are not effective bird collision deterrents, unless they cover a substantial portion of the glass. At that point, however, the aesthetic disadvantages are obvious. A properly designed fritted glass pattern is a much better choice, offering greater clarity and visibility, while presenting effective bird protection.

Spandrel glass is the non-vision (opaque) portion of the exterior wall of a multi-story commercial building. It is located between the sill of the vision glass assembly above and the head of the vision glass assembly below.

A curtain wall is an exterior building wall which carries no roof or floor loads. It consists mainly or entirely of metal or a combination of metal, glass and other surfacing / cladding materials supported by a metal framework. There are two basic types of curtain wall:

• Custom – The curtain wall is designed specifically for one project, using unique parts, components, and details specially-made for this purpose;
• Standard – The curtain wall is primarily made up of parts, components, and details standardized by the manufacturer and assembled in accordance with either the architect’s design or the manufacturer’s stock patterns and standard instructions.

A trombe wall is a passive solar design element. Trombe walls are built on the winter sun side of the building and consist of an external glass layer, standing off at some distance from a heat-absorbing internal wall. The glass allows sunlight through, while the wall behind it – which is typically designed in a dark, heat-absorbing color – passively collects the incident solar heat and radiates it into the interior.

Insulating glass units, or IGUs, were designed to keep buildings/homes warmer in the winter and cooler in the summer. Two or more lites of glass spaced apart and hermetically sealed to form a single-glazed unit with an air space between each lite. Heat transfer and sound transmission are reduced through the glass unit. Many decorative glass types, including Restoration Glass®, can be installed in IGUs to achieve the desired thermal performance and create or maintain the desired aesthetic.

Design load is a term describing a combination of: positive and negative wind loads, thermal loads, snow/ice loads, impact loads, seismic loads, interior pressure loads due to HVAC equipment or building stack effect, dead loads due to glass weight, and live loads. Standard ASCE 7 is the most utilized tool to determine the appropriate design load of a glass product.

Design pressure is the specified pressure a glass product is designed to withstand. It is determined by the design load.

The R-Value is the thermal resistance of a glazing system measured over 1 hour through a 1 sq. ft. area of the glazing unit for each 1° F temperature difference between the indoor and outdoor air. Essentially, it is a measure of resistance to heat gain or loss (insulative ability). The higher the R-value, the less heat is transferred through the glass.

R-Values rather than thicknesses can be compared for different materials, since 6″ (15.24 cm) of fiberglass (R-19) might compare with 12″ (30.48 cm) of wood or 18″ (45.72 cm) of stone.

U-Value measures how well a window or glass wall holds heated or cooled air inside the building. More specifically, it is the measure of heat energy transferred from one side of the glass unit to the other, measured by the amount of heat transferred through 1 sq. ft. of glazing for each 1° F temperature difference between the indoor and outdoor air. The lower the U-Value, the higher the thermal performance of the glass wall. U-Value can be improved by insulation, lamination, and specialty thermal coatings.

The Solar Heat Gain Coefficient (SHGC) measures how much solar radiation is admitted through a window or glass wall. It represents the solar heat gain through the glass, relative to the incident solar radiation.

Shading Coefficient is an older measure of solar radiation, and is the inverse of SHGC. The shading coefficient is the ratio of solar energy that passes through the glass, relative to a piece of 1/8” clear glass (which has a shading coefficient of 1.0).

The optimal amount of solar heat gain depends on the climate. A higher SHGC is generally preferred in colder, heating-dominated climates, such as Northern USA and Canada. A high SHGC it is more effective at collecting solar heat. During the longer winter heating season, the extra solar radiation becomes “free” heat. A lower SHGC is generally preferred in warmer, air-conditioning-dominated climates, such as Southern USA and Mexico. A low SHGC blocks heat from the sun. With a long air-conditioning season, reducing solar heat gain and cooling loads is a priority.

Relative Heat Gain (RHG) is the amount of heat gain through a glass product taking into consideration the effects of solar heat gain (shading coefficient) and conductive heat gain (U-value). The lower the RHG, the greater the glass restricts heat gain.

The percentage of solar energy (ultraviolet, visible light, and near-infrared), from 300 to 2,100 nanometers within the solar spectrum, transmitted through the glass.

Visible Light Transmittance (VLT) describes the percentage of visible light (approximately 390 to 780 nanometers within the solar spectrum) transmitted through the glass. It is determined by the glass color and thickness. Clear float glass has 75% to 92% VLT; colored glass has 14% to 85% VLT.

The Outside-Inside Transmission Class (OITC) Rating is used to classify the performance of glazing in exterior applications. It is based on ASTM E-1332 Standard Classification for the Determination of Outdoor-Indoor Transmission Class. While STC rating is based on a “white noise” spectrum, this standard utilizes a source noise spectrum that combines aircraft/rail/truck traffic and is weighted more to lower frequencies.

A rating of the ability of an interior partition to attenuate sound, measured by the amount of decibel (dB) noise reduction at different sound frequencies. In essence, it reflects the noise reduction that the partition can provide. The STC for monolithic ¼” (6 mm) glass is approx. 31-32. The same thickness standard laminated glass is approx. STC 34, while Bendheim’s +2 Acoustic Glass has STC 36 at ¼” thickness. Bendheim’s uninsulated 4.5”-thick channel glass walls have STC 38; our insulated 4.5” channel glass walls reach STC 43. The STC rating of a standard 4.5” uninsulated stud wall is approximately 33. Lamination, particularly using specialized acoustic interlayers, significantly improves the glass STC; increased panel thickness can also enhance sound control.

STC measurements are derived by testing in accordance with ASTM E90, “Laboratory Measurement of Airborne Sound Transmission of Building Partitions.” STC values are attained by applying the Transmission loss (TL) values to the STC reference contour of ASTM E413, “Determination of Sound Transmission Class.”

Low-E (Low-Emissivity) coating is a thermal performance coating applied to the inside glass face to reflect long wave radiation and restrict heat transfer, thus improving the glass U-value. It is transparent when applied to float glass and iridescent on channel glass. Bendheim’s Lamberts channel glass with Low-E coating has an approximate U-value of 0.41.

Short-wave infrared energy comes directly from the sun, but is not felt as heat. It converts into heat when it strikes an object.

Long-wave infrared energy is the heat radiated from an object, which has received short-wave infrared radiation. You can often observe long-wave infrared energy as heat radiating from the surface of a hot sidewalk or roadway.

Channel glass is a translucent U-shaped glass produced in several widths ranging from 9″ to 19″, lengths up to 23 feet, and 1.5″ (for interior use) or 2.5″ (for exterior use) flanges. The flanges make the three-dimensional glass self-supporting, allowing it to create long uninterrupted spans of glass with minimal framing elements – ideal for daylighting applications.

Channel glass is relatively easy to install. Any competent commercial glazier with curtainwall or storefront installation experience can handle the channel glass installation. No specialized training is required. Cranes are often not required, as the individual glass channels are lightweight. Channel glass can be glazed on site, as seen in the image on the left, or pre-assembled at the glazier’s shop using Bendheim’s unique unitized channel glass systems.

Bendheim’s channel glass is available in several light-diffusing decorative surface textures, hundreds of translucent or opaque ceramic frit colors, as well as a range of thermal performance coatings.

Channel Glass Manufacture:

Produced in Europe’s first oxygen-fired glass melting furnace, Bendheim’s Lamberts® channel glass is the world’s most environmentally-friendly cast glass today. Its basic ingredients are sand, limestone, soda ash, and carefully recycled pre- and post-consumer glass. The mix is combined in the sophisticated oxygen-fired melting furnace, and emerges from the furnace as a ribbon of molten glass. It is then drawn over a series of steel rollers and formed into a U-shape. As the resulting U-glass ribbon is cooled and hardened, it creates a continuous glass channel of the specified dimensions and surface finish. The endless ribbon of channel glass is carefully annealed (control-cooled) and cut to the desired lengths, prior to final processing and shipping.

Sustainability:

Double-glazed facades using Bendheim’s Lamberts® channel glass have a demonstrably lower carbon footprint than most traditional curtain walls. This exceptional CO2 performance is due to the manufacturer’s decades-long commitment to eco innovation. It includes the use of oxygen and natural gas to fire the glass-melting furnace, as well as the implementation of 100% renewable electricity throughout the factory. For more information on the glass’ eco performance, please download the Environmental Product Declaration. Bendheim Wall Systems’ channel glass is produced according to the German quality standard DIN EN 752.7.

Using Low-e coating on surface #3, SHGC coating (our Azur coating) on surface #2, and a thermal insulation material (TIM) in the cavity of a double-glazed channel glass wall can deliver the highest thermal performance. This combination was used on Silver Lake Branch Library in Los Angeles, CA, where it achieved a calculated U-Value of 0.13, SHGC below 0.30, and approx. 33% visible light transmission (VLT).

A standard double-glazed, uncoated channel glass wall provides a U-Value of 0.49 and a Solar Heat Gain Coefficient (SHGC) of 0.67.

The thermal performance of channel glass walls can be progressively improved, reaching a U-Value of 0.19, by adding our Low-e coating and a thermal insulation material (TIM), such as Okapane.

The most common method to improve the thermal performance of the channel glass wall is to improve the U-Value. The lower the U-Value, the higher the performance of the glass wall.

The first step is to add a Low-e (low-emissivity) coating to one side of the channel glass wall. This improves the U-Value from 0.49 to 0.41.

The next step in to add a thermal insulation material (TIM), such as Okapane (bundled acrylic straws), in the cavity of a double-glazed channel glass wall. This will improve the U-Value of uncoated channel glass from 0.49 to 0.25. Used in conjunction with a Low-e coating, thermal insulation allows you to achieve U-Value of 0.19.

These thermal performance improvements result in lower VLT (visible light transmission), but largely maintain the daylighting advantages of the channel glass wall. Uncoated channel glass allows approx. 72% of visible light to come through. Low-e-coated channel glass allows approx. 65%; Low-e-coated, thermally insulated (added TIM) channel glass allows approx. 40% of visible light to come through. TIMs are also non-see-through dense white materials, but they remain good daylighting products.

There aren’t any significant thermal performance differences between different thermal insulation materials (TIMs) for channel glass walls. All thermal insulation materials typically used with these applications have essentially the same U-Value, SHGC, and light transmission performance. However, Nanogel / Lumira can be costly, may be susceptible to settling, and does not completely fill the channel glass cavity the way Okapane does. Therefore, the actual insulation value of Nanogel is a little less than its advertised performance.

Nanogel consists of polycarbonate tubes filled with aerogel pellets. Okapane consists of miniature acrylic tubes covered by translucent fiberglass sheeting.

A rainscreen is an architectural, exterior over-cladding system that stands off from the building’s external weather-resistant barrier. It envelopes and protects the building from water infiltration, controlling water drainage and evaporation.

In lay terms, a rainscreen is akin to an elegant raincoat that protects the building from the elements, while delivering an added dose of style. It can completely transform the appearance of an existing building: Watch video.

There are two types of rainscreen systems: drained and back-ventilated, or pressure equalized. Both types allow water to escape and air to circulate behind them. Both are available from Bendheim Wall Systems.

Rainscreen facades can reduce the risk of mold, mildew, and water damage to buildings. They can breathe new life into existing structures by presenting an attractive, refreshed, modern face. And they can accomplish this without disrupting occupants or requiring costly, wasteful, time-consuming demolition.

Bendheim Wall Systems’ flat glass rainscreens are open, drained and back-ventilated or pressure-equalized systems. If condensation occurs, it is expected to quickly dissipate.

The following three elements must be present to create a water leak in the building envelope:

1. water (rain, melting snow and ice);
2. an opening or a weak point in the building envelope, through which water can penetrate; and
3. pressure (wind force)

Bendheim glass rainscreen systems are drained and back-ventilated or pressure-equalized, creating a barrier envelope around the building to minimize or prevent water infiltration.

All systems recommended for exterior application, including Wall-F, Wall-H, and Wall-VH, were rigorously tested in accordance with ASTM & AAMA requirements for Water Penetration, Pressure Equalization, Air Leakage, and Structural Performance. All systems performed admirably, and received the best rating for prevention of water penetration

There are multiple functional and aesthetic benefits to choosing a Bendheim Wall Systems’ glass rainscreen: from the ability to completely transform the appearance of a building through elegant decorative glass, to ease of installation and maintenance.

Among the main benefits of a glass rainscreen is protection against the elements. Water is the most significant factor in the premature deterioration of a building, and each of Bendheim’s tested rainscreen systems offers an effective envelope solution to moisture penetration. Even when the building’s substructure is made of wood, the glass can protect and ensure its stability and performance for hundreds of years. Bendheim rainscreen systems also accommodate the use of weatherproof membranes behind the glass in combination with opaque glass varieties.

Bendheim Wall Systems, rainscreens can dramatically change the appearance of an otherwise structurally sound building and preserve it for years to come. Installing a decorative glass rainscreen over the existing facade is a far less costly process than traditional demolition, repair, and re-glazing of exterior skins. It can be installed without accessing the building interior, disrupting occupants, or interrupting normal building operations.

New construction and retrofit projects alike are great candidates for the clean, transformational design of Bendheim Wall Systems’ decorative glass rainscreens. Our rainscreens install with ease in front of most building facades. Please visit our Project Gallery to browse a variety of new construction and retrofit installations.

A rainscreen can be installed on any building with a deteriorating or damaged facade, provided the building is structurally sound. The facade should be fixed to the extent possible, under the direction of a structural engineer. An air and vapor barrier and rigid insulation should be installed behind the rainscreen system. The rainscreen will provide the restored facade the necessary moisture protection for many years to come, along with insulation and maintenance benefits.

The extent of fixes necessary to the existing damaged facade will vary from project to project. It depends on the unique circumstances of each building in question, including level of damage, local building codes and requirements, and design intent for the restored building. The structural engineering and architectural teams must assess all variables to make an informed decision. A structural engineer must also determine the ability of the existing facade to support the new rainscreen system. In some cases, if the facade is not structurally sound but restoring it is not possible, the rainscreen supports may be attached (drilled) directly into the building slabs, by-passing the facade. This avoids loading the new rainscreen system onto the damaged facade.

A rainscreen cannot be directly compared to repainting a facade or fixing its masonry. Paint and new mortar do not offer any significant enhanced protection against water penetration or insulation benefits. They are aesthetic fixes and damage will likely reoccur. A rainscreen offers the possibility for extreme facade makeover, as well as proven protection against the elements. Bendheim’s decorative glass rainscreen systems, in particular, have been rigorously tested in accordance with ASTM and AAMA requirements for water penetration and structural performance, and achieved splendid results. Glass is also non-combustible, an essential added benefit, especially in areas requiring fire protection by building code.

Depending on the unique building circumstances, as well as the materials and techniques required to repair aesthetic facade damage, the cost of a Bendheim glass rainscreen could be on par with other fixes, while completely transforming the appearance of the building and providing advanced moisture protection.

With a couple of simple actions, Bendheim Wall Systems’ decorative glass rainscreens can completely transform the appearance of uninspired, unmemorable old buildings into beautiful, contemporary architecture. First, pre-attach the Bendheim glass fittings to steel supports and install the steel on top of the structure. Then, select from Bendheim’s virtually limitless decorative glass options: from gently obscuring Dura-Etch® glass to custom printed images and designs. Even plain clear glass can create big impact.

Yes, our systems can be engineered for any building type: low-rises, mid-rises, and high-rises. The glass panel size and fitting spacing will be adjusted based on the design wind load for each project. Please send us your design wind load and project information to rainscreens@bendheim.com.

Yes. A unique combination of advanced fittings minimizing the need for visible hardware and Bendheim’s expertise in architectural glass allow us to provide the first rainscreen systems of their kind, delivering the combined benefits of protection against the elements and daylight advantages (when specified with transparent or semi-transparent glass panels).

Our Lumi Frit™ Surface 1 fritted glass, Dura-Etch® and SatinTech® etched glass varieties minimize reflections and create walls visible to birds, curtailing the risk of accidental bird collisions. We can also offer a range of bird-friendly glass patterns designed to the bird-safe “2 x 4″ and  2″ x 2” rules. Textured Bendheim decorative glass varieties, including our Lamberts® channel glass, are also appropriate for use in bird-friendly architecture.

Bird-friendly glass options are important in exterior applications. According to the American Bird Conservancy (ABC), the leading advocacy organization for bird-friendly architecture, up to a billion birds per year fall victim to glass collisions, hundreds of millions of those in North America alone. Glass facades and corners made of clear, highly translucent, or reflective glass can be particularly deadly to birds.  With this in mind, Bendheim offers a range of architectural glass varieties meeting ABC guidelines.

Yes, from the use of recycled materials to eliminating the need for wasteful demolitions, Bendheim Wall Systems’ glass rainscreens can help buildings hide their old or unattractive facades with a minimum investment in new materials and labor. Additionally, numerous installations in our Project Gallery, including the pictured projects, were designed to the demanding European Passivhaus green standard.

The various clip designs differ in aesthetics – flat, horizontal, and/or vertical overlap – and the thickness of the panels they can accommodate. Please contact us at rainscreens@bendheim.com or call 1.800.221.7379, ext. 237, to discuss your unique project needs, so that we may help you select the optimal system components.

Bendheim Wall Systems’ glass rainscreens recommended for exterior application – Wall-F, Wall-H, and Wall-VH – have been rigorously tested in accordance with ASTM and AAMA requirements for Water Penetration, Pressure Equalization, Air Leakage, and Structural Performance. All three systems performed admirably.

Wall-F fittings have been fully tested in accordance with ASTM E330-02, AAMA 509-09, and AAMA 508-07 (passed). Wall-F AAMA 509-09 classification: V12/W1.
Wall-H fittings have been fully tested in accordance with ASTM E330-02 and AAMA 509-09. Wall-H AAMA 509-09 classification: V27/W1.
Wall-VH fittings have been fully tested in accordance with ASTM E330-02 and AAMA 509-09. Wall-VH AAMA 509-09 classification: V28/W1.
Test results are available on request. Please e-mail rainscreens@bendheim.com.

ASTM E330-02 Structural Performance Test: The three systems withstood and exceeded the testing facility’s wind load generation capacity for testing positive and negative pressures. The systems far exceeded the loads needed to pass industry requirements.

AAMA 508-07 Pressure Equalized Rainscreen Wall Cladding Systems Test: Wall F with joint gaskets passed with excellent results. The pressure equalized system prevents moisture from accessing the building envelope and/or helps the drainage of any moisture that finds its way behind the glass.

AAMA 509-09 Drained and Back Ventilated Rainscreen Wall Cladding Systems Test: Tests a system’s capability to manage and drain any water entering behind the cladding, and if it is sufficiently vented to allow the cavity to dry. All three systems received the best rating for prevention of water penetration. All the systems are drained and back-ventilated, featuring open joints that allow air to circulate.

Tempered and/or laminated Bendheim glass is a safety glazing product, meeting the requirements for ANSI Z97.1 and the Consumer Product Safety Commission Standard 16 CFR 1201.

Bendheim Wall Systems’ clip-supported rainscreens have several advantages over spider-type rainscreen systems: They are easier to engineer; do not weaken the glass with holes or notches; use more budget-friendly glass (drilling & notching add significantly to the cost of the glass); require less exactness during installation; and install with much greater speed and ease.

Bendheim Wall Systems’ Decorative Glass Rainscreens may range significantly in price: from under $30.00/sq. ft. to over $75.00/sq. ft. While the choice of fittings does affect price, the greatest variable is the choice of glass: tempered and heat soak tested or laminated glass, regular or low-iron glass, patterns, textures, thickness, and the size of each glass panel.

Due to these variables, it is simply not possible to provide a standardized price list for these systems. Please contact your local Bendheim Wall Systems’ sales representative. With some discussion about your design considerations and, perhaps, some basic drawings, we will gladly develop budget material costs based on your design.

The standard warranty for Bendheim Wall Systems’ decorative glass rainscreens is 5 years from the delivery date of the complete system.

Lead times depend on project size and product requirements. For most standard rainscreen systems – comprising our core glass options and Längle fittings in standard finishes – typical lead times are 6-8 weeks. Custom orders may have longer lead times, and are based on the size of the project and unique product requirements. To expedite installation, the fittings can be delivered to the customer in advance of the glass panels, approx. 5 weeks after order acceptance.

Bendheim Wall Systems’ decorative glass rainscreens are a commercial product, and glass samples are available to practicing A&D professionals on request (charges may apply). Please contact your local Bendheim Wall Systems representative to request a presentation of the clip systems and/or glass samples.

Bendheim stocks over 2,000 different decorative glass varieties and offers virtually unlimited custom design solutions. The first step in creating a unique solution for your project is understanding your design intent. Please share with us your ideas and project details: is the application exterior or interior; what is the location and size of the project; what is the overall effect you want to achieve; what is the budget? You can e-mail us at rainscreens@bendheim.com or call us at 1.800.221.7379, ext. 237.

Standard Glass Options:

Our standard glass options contain a selected variety of glass types, ranging from clear to color fritted glass designs. Visit our Product Catalog for a listing of currently available glass options.

Custom Glass Options:

Bendheim has decades of experience in developing decorative glass. Custom glass options, whether unique patterns or specialty colors, may only be limited by the customer’s imagination. Please contact us at rainscreens@bendheim.com or call 1.800.221.7379, ext. 237, to discuss how we can help realize your unique design vision.

Yes, Bendheim Wall Systems is happy to accommodate custom specifications on medium- and large-size orders. Both the glass panels and fittings can be specified in a virtually unlimited spectrum of custom colors. For more information, please e-mail your color selections and project information to rainscreens@bendheim.com or contact us at 1.800.221.7379, ext. 237.

Our rainscreen fittings are available in standard powder coated silver finish or clear anodized finish. In addition to the standard finishes, they are also available in a virtually limitless custom color palette. Custom colors specified through Pantone® and other color systems will be translated to their closest RAL color match, please see www.ralcolor.com. Order minimums and setup charges apply.

The glass rainscreen panels can be oriented vertically or horizontally. Horizontal orientation can accommodate larger panel sizes for the same design wind load.

The maximum allowable glass rainscreen panel size depends on the design wind load, the thickness of the glass, and other factors. For further information, please e-mail us your specified wind load requirements and desired panel size to rainscreens@bendheim.com or contact us at 1.800.221.7379, ext. 237.

Yes, rainscreen panels can be specified with custom shapes and cutouts to accommodate logos, etc., as illustrated in this project. Note custom shapes are not covered by our performance tests.

Installation of any of Bendheim Wall Systems’ flat glass rainscreens is relatively easy and does not require any previous training or special expertise. The fittings can be affixed to steel, aluminum, timber, or other substructures. The smartly engineered clips feature unique, patented user-friendly designs: they adjust easily to field conditions and can be relatively quickly installed, resulting in significant labor cost savings. Unlike other systems, individual glass panels can later be quickly and easily replaced without having to deglaze surrounding panels: See the YouTube video demonstration below, showcasing how a single man can replace a glass panel in our Wall-F system in less than 1 minute.

Bendheim decorative glass rainscreens are exceptionally easy to maintain. To start with, glass is an ideal material for rainscreen applications “due to its inherent durability, ease of maintenance, and resistance to staining and graffiti. A non-porous material, glass is well-positioned to stand up to the punishing effects of water, wind, and time.” (Source: “Glass Rainscreen Systems Enhance the Building Envelope,” Construction Canada, Feb. 2015)

Bendheim’s opaque, textured, and patterned glass varieties seldom require cleaning, as water tends to roll off the smooth glass surfaces. The obscuring effect of the opaque fritted glass color, texture, or pattern, makes cleaning the inside face of Bendheim rainscreens featuring these glass varieties superfluous. Periodically, traditional window washing techniques can be used to clean the outside face of the glass rainscreen.

For vision areas where clear glass panels are used to preserve daylighting and views, cleaning the rainscreen system inside and out can be accommodated in a variety of ways:

1. Ensure vision panels are installed in front of windows that can be opened inward.
2. For rainscreens that are two to three elevations tall, the inside face of the glass can be sprayed with a water hose from above.
3. The system can be designed to accommodate a walkway between the building facade and the rainscreen, allowing vision areas to be cleaned from behind, regardless of the height and span of the rainscreen.

Our powder-coated / anodized compression glass fittings are also durable and do not require special maintenance. Furthermore, the patented quick assembly method of the Bendheim systems allows for damaged glass panels to be easily replaced without having to deglaze surrounding panels, in as little as one minute: Please see our brief video demonstration below.

Yes, Bendheim can provide an unsurpassed variety of decorative glass options for interior wall cladding applications, in combination with our tested, secure, easy-to-install Längle glass fittings. Our Wall-F (Flat System) and Wall-LH (“Light” Horizontally Overlapping System) are particularly effective for interior feature walls. Additionally, Wall-LH fasteners accommodate glass thickness ranging from 1/4” (6 mm) to 5/16” (8 mm), perfect for most interior applications.