Glass and Glazing

This standard governs the furnishing and installation of architectural glass and the materials and accessories used to glaze it into framing supplied under other standards. It applies to vision glass and related glazing in storefronts, curtain walls, windows, exterior and interior doors, sidelights, transoms, borrowed lites, interior glazed partitions, and similar building glazing infill. The standard establishes requirements for the glass products themselves (annealed, heat-strengthened, fully tempered, laminated, coated, and insulating glass units), for spandrel and decorative glass, for the glazing materials and accessories (sealants, gaskets, setting blocks, and tapes) that retain and seal the glass, and for the fabrication, installation, testing, cleaning, and warranty of the glazing work.

Glass is simultaneously a structural element, an environmental separator, a safety component, and an architectural finish. A single lite must resist wind and snow load without breaking, survive thermal stress from differential heating, satisfy safety-glazing requirements where it occupies a hazardous location, deliver the energy performance the building's compliance documents require, and present an acceptable visual appearance free of distortion, haze, and edge defects. These requirements cross-couple: the heat treatment selected to resist thermal stress changes the glass type factor used in the load-resistance calculation; the coating selected to reduce solar heat gain changes the surface that must carry it within the insulating glass unit; the laminated interlayer chosen for safety or acoustics changes the unit weight and the glazing-pocket bite. The Contractor shall treat the glass as a coordinated system and shall reconcile structural, thermal, safety, and visual requirements against one another before any glass is ordered.

The glass type for each opening, the dimensions of each lite, the performance values required at each orientation, and the locations requiring safety glazing shall be as indicated on the contract drawings and the glazing schedule. This standard establishes the minimum product, performance, fabrication, and installation requirements applicable to all of those conditions. Coordinate this work with Aluminum Entrances And StorefrontsAluminum Entrances and StorefrontsResolves to the current adopted revision.sync/aluminum-entrances-and-storefronts and Glazed Curtain WallsGlazed Curtain WallsResolves to the current adopted revision.sync/glazed-curtain-walls for the framing systems and glazing-pocket geometry that receive the glass; with Doors Frames And HardwareDoors, Frames, and HardwareResolves to the current adopted revision.sync/doors-frames-and-hardware for glazed openings in hollow metal, aluminum, and wood doors; with Overhead Coiling DoorsOverhead Coiling DoorsResolves to the current adopted revision.sync/overhead-coiling-doors where vision lites occur in service openings; and with Building Thermal InsulationBuilding Thermal InsulationResolves to the current adopted revision.sync/building-thermal-insulation for the continuity of the building thermal envelope at the glazing perimeter.

Glass products, fabrication, glazing materials, performance testing, and installation shall comply with the latest adopted edition of the referenced standards. Where the contract documents or the adopted building code impose more stringent requirements than a referenced standard, the more stringent requirement shall govern. The Contractor shall resolve conflicts in writing with the Engineer of Record before proceeding.

The following submittals shall be submitted for review and returned before glass is fabricated or ordered. Glass, IGU, and glazing-accessory submittals shall be coordinated into a single review package, keyed to the glazing schedule, so that the glass makeup, heat treatment, coating surface, and safety-glazing designation for every lite are reconciled against the framing system that receives them.

Glazing Schedule: A schedule identifying every glass type by designation, keyed to the contract drawings, listing for each type the glass makeup (monolithic, laminated, or IGU), the thickness and heat treatment of each ply, the coating type and surface number, the interlayer type and thickness for laminated lites, the spacer type and gas fill for IGUs, the safety-glazing designation where applicable, and the locations at which the type is used.

Glass Strength and Thickness Calculations: Load-resistance calculations per ASTM E1300 for each glass type and the largest lite of that type, demonstrating that the selected glass type, heat treatment, and thickness resist the design wind and snow loads at a probability of breakage not exceeding 8 lites per 1,000 (Pb ≤ 0.008). For projects where the glass is a designated structural element or where local jurisdiction requires it, calculations shall be signed and sealed by a professional engineer licensed in the project jurisdiction.

Product Data: Manufacturer's published data for each glass product, coating, interlayer, IGU sealant system, spacer, gas fill, and glazing accessory, including the optical and thermal properties (U-factor, SHGC, VT, and exterior and interior visible reflectance) of each coated and insulating glass configuration.

Insulating Glass Unit Certification: Evidence that the IGU fabricator is certified under the Insulating Glass Certification Council (IGCC) or the Insulating Glass Manufacturers Alliance (IGMA) program and that the specific unit construction has passed durability evaluation per ASTM E2190 (using the test methods of ASTM E2188 and the fogging test of ASTM E2189).

Heat-Soak Test Documentation: Where heat-soak treatment of fully tempered glass is required, the fabricator's heat-soak process certification confirming the soak temperature, dwell time, and protocol (EN 14179 or equivalent), and confirmation that the project glass was processed through the documented cycle.

Thermal Stress Analysis: For glass exposed to partial shading, interior shading devices close to the glass, dark-colored or spandrel back-up, or other conditions producing differential heating, a thermal-stress analysis by the glass fabricator confirming the selected heat treatment resists the calculated edge and center stress without breakage.

Samples: Samples of each glass type, minimum 12 in. by 12 in., showing color, tint, coating appearance, and (for laminated and spandrel glass) interlayer or frit appearance. For coated and tinted glass, samples shall be viewed in both transmitted and reflected light and against the actual or a representative background.

Field-Constructed Mock-Up Glass: Where a project mock-up of the framing system is required, the glass furnished for the mock-up shall be of the project glass type, coating, and makeup so that color, reflectance, and visual quality are evaluated in the installed condition.

At substantial completion the Contractor shall provide the following closeout submittals before final acceptance.

• As-built glazing schedule reflecting any field changes to glass type or location
• Cleaning and maintenance instructions for the glass, coatings, and glazing sealants, including the glass and coating manufacturers' approved cleaning products and the products that shall not be used
• IGU warranty from the unit fabricator
• Laminated glass warranty (interlayer delamination) where laminated glass is furnished
• Coated glass warranty (coating defects and, for exterior coatings, durability) where applicable
• Glazing sealant and structural silicone warranty where wet or structural glazing is used

The glass fabricator shall demonstrate not less than five years of continuous production of architectural glass of the types specified. The insulating glass unit fabricator shall be certified under the IGCC or IGMA durability certification program for the unit construction furnished, and shall maintain that certification for the duration of fabrication. The laminated glass fabricator shall be experienced in producing laminated architectural glass to ASTM C1172 for the interlayer type specified.

The glazing contractor shall employ glaziers experienced in the glazing methods used on the project. Where structural silicone glazing is used, the glaziers shall be trained and approved by the structural silicone sealant manufacturer, and the sealant manufacturer shall review the structural joint design, confirm substrate compatibility and adhesion, and provide on-site instruction before structural glazing begins.

To the extent practical, all primary glass of a given type shall be obtained from a single primary glass manufacturer and a single fabricator so that color, coating, and visual characteristics are consistent across the project. Tinted, coated, and spandrel glass shall be from a single production run wherever a continuous expanse of glass is visible as a unified field, because lot-to-lot color variation in tints and coatings is visible side by side even when each lot independently meets specification.

Glass shall meet the visual quality requirements of ASTM C1036 for the applicable quality designation. Heat-treated glass shall meet the roll-wave and bow/warp limits of ASTM C1048 and shall be evaluated for roll-wave optical distortion per ASTM C1651 where reflected-image quality is important to the design. Glass shall be free of visible defects (bubbles, inclusions, scratches, digs, and coating voids) when viewed under the conditions and at the distance prescribed by ASTM C1036.

Each lite shall resist the design wind load and, where applicable, the design snow load and self-weight, determined per ASTM E1300, at a probability of breakage not greater than 8 lites per 1,000 (Pb ≤ 0.008) for vertical glazing. ASTM E1300 establishes the load resistance of a lite from its type, thickness, area, support condition, and aspect ratio, applying a glass type factor (GTF) that scales the resistance of annealed glass to account for the higher strength of heat-strengthened (GTF ≈ 2) and fully tempered (GTF ≈ 4) glass. For an insulating glass unit, ASTM E1300 distributes the applied load between the two lites in proportion to their stiffness (the load-sharing factor) and the load resistance of the unit is governed by the weaker lite.

The design wind pressure shall be derived from the project structural drawings and the building code wind determination for the project location, height, and exposure. Increasing glass thickness, selecting a higher heat treatment, or laminating two plies are the available means of increasing load resistance; the selection shall be coordinated with the thermal-stress, safety-glazing, and acoustic requirements so that a single makeup satisfies all governing criteria.

Glass breaks from thermal stress when one part of a lite heats and expands while a cooler part (typically the shaded edge captured in the frame) restrains it, producing tensile stress at the edge. The risk increases with absorptive (tinted or coated) glass, partial shading from overhangs or adjacent structures, interior shades or blinds close to the glass, dark spandrel or insulation back-up behind the glass, and damaged or poor-quality glass edges that concentrate stress. Annealed glass tolerates the least thermal stress; heat-strengthened glass roughly doubles the tolerance and is the standard remedy; fully tempered glass tolerates the most but is not selected for thermal stress alone because of its other characteristics.

Where the thermal-stress analysis indicates that annealed glass is inadequate, the glass shall be heat-strengthened (the preferred remedy) or fully tempered. The edges of heat-treated glass intended to resist thermal stress shall be clean-cut and free of vents, shells, and serious damage, because edge damage defeats the strength gain of heat treatment.

The glass or insulating glass unit shall provide the center-of-glass and, where the unit is rated as part of a fenestration product, the whole-product U-factor, solar heat gain coefficient (SHGC), and visible transmittance (VT) required by the project energy-compliance documentation, with optical and thermal properties determined per NFRC 300 and the product ratings certified per NFRC 100 (U-factor) and NFRC 200 (SHGC and VT).

A standard double-glazed IGU with a single low-emissivity coating, argon fill, and a warm-edge spacer typically achieves a center-of-glass U-factor near 0.24 to 0.29 Btu/h·ft²·°F; a triple-glazed unit with two low-e coatings reaches the 0.10 to 0.18 range. The SHGC and VT are governed by the coating: a high-solar-gain low-e coating delivers a high VT with a moderate-to-high SHGC for heating-dominated climates, while a solar-control (spectrally selective) low-e coating delivers a low SHGC while retaining a usable VT for cooling-dominated climates. The light-to-solar-gain ratio (VT divided by SHGC) describes how much daylight the glass admits per unit of solar heat; spectrally selective coatings push this ratio above 1.25 and are the common default for daylit commercial buildings. The Architect shall confirm that the U-factor, SHGC, and VT targets are simultaneously achievable with a single coating before the makeup is finalized.

Where the contract documents require acoustic performance, the glass makeup shall achieve the specified Sound Transmission Class (STC), tested per ASTM E90 and rated per ASTM E413. Acoustic performance is governed primarily by the glass makeup: asymmetric lite thicknesses (which break up coincidence dip resonance), a laminated lite with an acoustic interlayer, and a wider air space improve STC. Standard symmetric double glazing achieves roughly STC 32 to 35; asymmetric and laminated makeups reach STC 38 to 45.

Glazing in the hazardous locations defined by IBC Section 2406.4 shall be safety glazing complying with the impact-test requirements of 16 CFR 1201 (the U.S. Consumer Product Safety Commission standard) for the applicable category, or, where the exception applies, ANSI Z97.1 for the applicable class. Hazardous locations include glazing in doors; glazing adjacent to doors within the defined arc and distance; glazing in fixed and operable panels meeting the area, edge-height, and walking-surface-proximity tests; glazing in guards and railings; glazing adjacent to stairways, landings, and ramps; and glazing enclosing or adjacent to wet areas such as showers, tubs, pools, and saunas. The locations requiring safety glazing shall be as indicated on the contract drawings and glazing schedule and confirmed against IBC 2406.4.

16 CFR 1201 defines two impact categories by glazed area and impact energy: Category I, for small lites (less than 9 ft², or 1,296 in²), tested at 150 ft·lbf; and Category II, for large lites (9 ft² and greater) and all glazing in doors, tested at 400 ft·lbf. Glazing in doors and in storefront sidelights, and most large vision lites in hazardous locations, require Category II.

Safety glazing requirements are satisfied by fully tempered glass or by laminated glass that passes the applicable impact test. Where post-breakage retention matters — guards, glazing over occupied space, glazing where falling cullet would create a secondary hazard — laminated glass is preferred over monolithic tempered glass because the laminated lite holds together on the interlayer after breakage, whereas tempered glass disintegrates into a curtain of granular cullet that leaves the opening unprotected.

Each lite of safety glazing shall bear a permanent label identifying the fabricator, the safety-glazing standard met (16 CFR 1201 category or ANSI Z97.1 class), and the glass type, per IBC Section 2406.3. The label shall be visible after glazing and shall not be removed until the building official has inspected the installation, except where the alternative certificate-of-compliance provisions of the code are used.

Where the contract documents require bird-friendly glazing (an increasingly common requirement under local ordinances and green-building credits), the glazing shall present a visual pattern that birds perceive as a barrier. Patterns qualify when applied per the established spacing convention: continuous lines or elements not more than 2 in. apart in the vertical direction and not more than 4 in. apart in the horizontal direction (the "2 by 4 rule"), with elements at least 1/8 in. wide. The most durable patterns are a ceramic frit or an etched/printed pattern on the first (exterior) surface, or a second-surface pattern with the low-e coating placed behind the pattern so the pattern remains visible from outside. Where a bird-deterrent pattern is required it shall be as indicated on the contract drawings for pattern, coverage, and surface.

Primary flat glass shall be float glass conforming to ASTM C1036, of the type and class indicated. Clear glass is the default; low-iron glass shall be specified where the green tint and reduced transmittance of standard clear glass are objectionable (large clear expanses, glass with white or light interlayers, display and showcase glazing, and applications requiring the highest visible transmittance). Tinted (body-colored) glass reduces solar transmittance and visible transmittance and shall be coordinated with the coating selection, since tint and coating both affect SHGC and appearance.

Heat-treated glass shall conform to ASTM C1048: Kind HS (heat-strengthened) or Kind FT (fully tempered). Annealed glass (untreated float glass) is used where neither safety glazing nor elevated strength is required. Heat-strengthened glass, with a surface compression of roughly 3,500 to 7,500 psi, is the standard choice for resisting thermal stress and for spandrel glass; it breaks into large fragments that tend to stay in the opening but is not a safety-glazing material. Fully tempered glass, with a surface compression of 10,000 psi or greater, is a safety-glazing material that breaks into small granular fragments; it is required in hazardous locations where laminated glass is not used.

Heat-strengthened glass shall not be substituted where safety glazing is required, and fully tempered glass shall not be specified merely as a default "stronger" glass where it is not needed, because tempered glass is more prone to spontaneous breakage from nickel-sulfide inclusions and exhibits more roll-wave distortion than heat-strengthened glass.

Fully tempered glass contains a small statistical population of nickel-sulfide (NiS) inclusions that can, over years in service, undergo a phase change accompanied by a slight volume increase; when an inclusion sits in the central tensile zone of the lite, the resulting local stress can cause spontaneous breakage with no external cause. Heat-soak treatment accelerates this phase change in the factory by holding the tempered glass at approximately 290 °C for a sustained dwell (per EN 14179 or an equivalent documented protocol), breaking susceptible lites before they ship and reducing the in-service spontaneous-breakage rate by roughly an order of magnitude. Heat-soak treatment shall be specified for fully tempered glass in overhead glazing, in glass guards and railings, in tall or inaccessible facades, and wherever spontaneous breakage would create a safety hazard or a high replacement cost.

Laminated glass shall conform to ASTM C1172, consisting of two or more plies of glass bonded by a continuous interlayer. Laminated glass provides post-breakage retention (the broken plies remain bonded to the interlayer), enhanced safety and security, acoustic improvement, and ultraviolet screening. The interlayer shall be selected for the governing requirement: polyvinyl butyral (PVB) is the standard general-purpose interlayer; an acoustic PVB (a softer damping layer) is selected where acoustic performance governs; and a stiff ionoplast interlayer is selected where post-breakage structural retention, edge stability, or higher load resistance governs (guards, overhead glazing, and high-load facades).

The plies of laminated glass may themselves be annealed, heat-strengthened, or fully tempered. Heat-strengthened plies are common because they retain large fragments bonded to the interlayer (preserving residual capacity), whereas tempered plies dice into small fragments that reduce the laminated unit's post-breakage stiffness. The ply heat treatment shall be selected with the structural and post-breakage requirements in mind.

Coated glass shall conform to ASTM C1376. Low-emissivity (low-e) coatings reduce radiative heat transfer across the IGU air space, lowering the U-factor; spectrally selective low-e coatings additionally reject solar infrared, lowering the SHGC while retaining visible transmittance. Coatings are produced by two processes: pyrolytic ("hard-coat"), applied at the float line and durable enough for monolithic and exposed use; and magnetron-sputtered vacuum deposition ("soft-coat"), which offers higher performance and more neutral color but must be enclosed within a sealed IGU and, for most products, requires edge deletion at the unit perimeter.

In an insulating glass unit the surfaces are numbered 1 through 4 from the exterior (surface 1 is the outboard exterior face; surface 2 is the outboard cavity face; surface 3 is the inboard cavity face; surface 4 is the interior room-side face). For cooling-dominated climates the solar-control low-e coating is placed on surface 2 so it rejects solar gain before it crosses the air space. For heating-dominated climates a high-solar-gain low-e on surface 3 admits and retains solar heat. A second low-e on surface 4 (an interior-face pyrolytic coating) can further reduce the U-factor in cold climates but shall be confirmed for cleanability and durability.

Insulating glass units shall be factory-fabricated dual-seal units certified under the IGCC or IGMA program and qualified for durability per ASTM E2190. The primary seal (polyisobutylene) controls moisture and gas permeation; the secondary seal (silicone, polyurethane, or polysulfide) provides the structural bond holding the unit together. Field fabrication of insulating glass units is prohibited; all units shall arrive sealed from the fabricator.

Per ASTM E2190 the certified unit shall maintain a final frost/dew point of −40 °C or colder (measured per ASTM E546 or E576) after durability conditioning, exhibit no fog after the ASTM E2189 fogging test, and — for argon-filled units — retain an average argon concentration of at least 80 percent across the test specimens. The Architect shall confirm that argon retention and the warranted seal life are consistent with the project's exposure and elevation, since gas fill diffuses slowly over the unit's life.

The spacer separating the lites and carrying the desiccant shall be a warm-edge spacer (stainless steel, thermoplastic, or structural foam) rather than a conventional aluminum box spacer, except where a specific structural or appearance reason requires otherwise. Warm-edge spacers substantially reduce the conductive heat loss and the condensation risk at the glass edge and modestly improve the whole-unit U-factor.

Spandrel glass conceals the floor-edge, structure, and insulation between vision-glass areas. Spandrel glass shall be heat-strengthened (not annealed) because the opaque back-up and the absorbed solar energy create high thermal stress; fully tempered glass is generally not used for spandrel because heat-strengthened glass resists the thermal stress while breaking into larger, retained fragments. The opacifier shall be a ceramic frit (a fired-on ceramic enamel) on surface 2, or an opaque film or applied opacifier, as indicated. Ceramic frit shall be fused during the heat-treatment cycle so it is permanent and durable.

Color match between fritted spandrel glass and adjacent vision glass shall be evaluated on samples and on the mock-up under daylight, because the perceived color of spandrel glass differs from vision glass even when the same coating is used. Where a uniform appearance between vision and spandrel areas is required, the frit color and coating shall be selected together with the vision-glass coating.

Wet glazing sealants and perimeter glazing sealants shall be elastomeric sealants conforming to ASTM C920, of the type, grade, class, and use compatible with the glazing-pocket geometry and the glass coating. Structural silicone glazing sealants shall additionally conform to ASTM C1184. The sealant manufacturer shall confirm compatibility with the glass coating, the IGU secondary seal, the setting blocks and spacers, and the framing finish, because incompatible sealants can attack the IGU secondary seal and cause premature seal failure.

Where the glass is retained by structural silicone glazing (the silicone sealant transfers wind load from the glass to the framing without a continuous mechanical capture on one or more edges), the design shall comply with ASTM C1401 (structural sealant glazing guide) and the structural silicone shall conform to ASTM C1184. The structural bite (the contact dimension of the structural sealant on the glass and the metal) and the glue-line thickness shall be sized by engineering calculation for the design wind load and the dead-load weight of the glass, signed and sealed where required by the jurisdiction. Structural silicone shall be applied in a controlled (typically factory or shop) environment wherever possible, with adhesion and compatibility verified before production.

Setting blocks shall be EPDM or silicone, 85 ± 5 Shore A durometer, conforming to ASTM C864, sized to support the full width of the glass edge (the full IGU thickness for insulating units) and long enough to keep the bearing stress within the glass manufacturer's limit. Edge blocks and spacers shall maintain the glass centered in the pocket and shall preserve the required edge, face, and bite clearances. Compression gaskets shall conform to ASTM C864 (dense) or ASTM C509 (cellular) as appropriate to the glazing-pocket design. Setting blocks and gaskets that contact an IGU secondary seal or a coated edge shall be confirmed compatible with those materials.

Dry-glazing gaskets shall be extruded EPDM, silicone, or thermoplastic, of the durometer and profile specified by the framing system, providing continuous compression against both glass faces. Preformed glazing tapes, where used, shall conform to ASTM C1281. Gaskets shall be installed in continuous lengths wherever possible; necessary splices shall be located at corners or at designated locations and shall be sealed.

All cutting, edge treatment, hole drilling, notching, and edge deletion of coatings shall be completed before heat treatment and before lamination or IGU assembly. Heat-treated and laminated glass and insulating glass units shall not be cut, drilled, or edge-worked in the field; field modification destroys the temper, breaks the laminate or seal, and voids the warranty. Edges of heat-treated glass shall be clean-cut and free of vents, shells, and damage that concentrate stress and defeat the strength benefit of heat treatment.

Where a sputtered (soft-coat) low-e coating is used in an insulating glass unit and the coating is not durable at the unit perimeter, the coating shall be deleted (removed) at the edge so that the IGU secondary seal bonds to bare glass, ensuring a durable seal. Coating edge deletion shall be performed by the glass fabricator before unit assembly, to the coating manufacturer's required deletion width.

Glazing shall comply with the GANA/NGA Glazing Manual, the framing manufacturer's published glazing instructions, and the glass and IGU fabricators' requirements. Glazing shall not begin until the framing is installed plumb, level, square, and weather-protected and the glazing pockets are clean and dry. Each lite shall be set on setting blocks, centered in the pocket with the required edge and face clearances and the required glazing bite, and sealed by the gasket or sealant system specified for that pocket.

Setting blocks shall be located at the quarter-points of the sill, unless the lite is large or has an unusual aspect ratio, in which case the glass fabricator's setting-block locations shall govern. Edge clearance, face clearance, and bite shall comply with the GANA/NGA Glazing Manual and the framing manufacturer's published instructions for the glass thickness and lite size. Inadequate edge clearance allows glass-to-metal contact and edge stress concentration; inadequate bite allows the glass to disengage under wind load.

Coated, laminated asymmetric, and tinted glass shall be installed with the correct face toward the exterior and the coating on the specified surface. The fabricator's orientation marking shall be verified at installation; a unit installed reversed delivers the wrong U-factor, SHGC, and appearance and shall be replaced, not reused. Insulating glass units shall be installed with the weep system (where the pocket is drained) clear and functioning so that incidental water in the pocket drains to the exterior and does not stand against the IGU edge seal.

Insulating glass units shall be glazed so that the unit edge seal is not continuously immersed in standing water and is not exposed to incompatible sealants, solvents, or continuous high temperature. Standing water and incompatible materials are the leading causes of premature IGU seal failure. Glazing-pocket weeps shall not be blocked by sealant, gaskets, or setting blocks.

The Architect or the Owner's testing agency may inspect installed glazing for correct glass type and orientation, setting-block placement, edge and bite clearance, gasket continuity, sealant tooling, and weep function. Glazing found with incorrect glass type, reversed orientation, inadequate clearance or bite, or a compromised edge seal shall be corrected or the affected lites replaced.

Where the framing standard or the contract documents require field water testing of the installed glazing (typically as part of the framing system test), the glazing shall be tested as part of that assembly. Glazing-related leakage (at gaskets, glazing sealant, or the weep path) identified during such testing shall be corrected and retested. This standard does not establish independent chamber tests for the glass; the glazing is verified as part of the framing system test under the applicable framing standard.

The IGU fabricator's IGCC or IGMA certification and ASTM E2190 durability qualification serve as the basis for accepting the units; no field durability test is required. Units delivered with a broken seal, visible internal condensation or fog, or a damaged edge seal shall be rejected and replaced before glazing.

Glass shall be protected from damage by adjacent construction operations from delivery through substantial completion. Welding, cutting, and grinding shall not be performed near installed glass without sacrificial shields; weld spatter and grinding sparks fuse into the glass surface and create inclusions that cannot be removed without replacing the lite. Glass shall not be marked with adhesive labels, paint, or tape applied directly to a coated surface, and protective films shall be removed within the film manufacturer's exposure limit so they do not bond permanently.

At substantial completion the glass shall be cleaned with a non-abrasive glass cleaner approved by the glass and coating manufacturers. Abrasive pads, scrapers, and razor blades shall not be used on coated glass surfaces, because they scratch and remove the coating. Acidic and alkaline construction-residue cleaners (masonry and concrete cleaners) shall not be allowed to contact the glass, coatings, or IGU edge seals.

The insulating glass unit fabricator shall provide a written warranty against IGU seal failure — visible obstruction, fogging, or moisture between the lites and, where applicable, loss of gas fill below the warranted threshold — for a minimum of 10 years from substantial completion.

The laminated glass fabricator shall provide a written warranty against interlayer defects (delamination, edge separation, and discoloration beyond published limits) for a minimum of 5 years from substantial completion.

The coated glass fabricator shall provide a written warranty against coating defects (peeling, cracking, deterioration, and, for exposed coatings, durability failure) for a minimum of 5 years, and for exterior durable coatings for a minimum of 10 years, from substantial completion.

Where structural silicone glazing or wet glazing is used, the sealant manufacturer shall provide a written warranty against adhesive and cohesive sealant failure for a minimum of 10 years for ASTM C920 Class 50 or 100 and ASTM C1184 structural silicone sealants.

Warranties shall be written in the name of the Owner, shall be transferable for the warranty term, and shall not exclude lites replaced under the field quality-control corrections required by this standard. Blanket exclusions for spontaneous breakage of tempered glass shall not be accepted where heat-soak treatment was required and performed; the warranty shall cover spontaneous breakage of heat-soaked tempered glass attributable to nickel-sulfide inclusions for the warranted term.