Published glass industry care guidance that matters most on tall buildings with coated, tinted or heat-treated glass.
Infrequent Or Improper Cleaning Can Permanently Damage Glass. This Paper Summarizes NGA And Vitro Care Guidance For High-Rise Curtain Walls, Including Cleaning Frequency, Coated And Heat-Treated Glass, And Rundown Staining.
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A high-rise curtain wall has a lot of glass, much of it coated, tinted or heat-treated, and it is hard to reach. Glass industry guidance warns that infrequent or improper cleaning can permanently damage glass. This paper summarizes the published care practices from the National Glass Association (NGA) and Vitro Architectural Glass that matter most on tall buildings.
Key Points
- Damage Can Be Permanent: "Glass products can be permanently damaged if infrequently or improperly cleaned." NGA FB01-00
- Twice A Year As A Baseline: "Generally, twice per year cleaning is sufficient," with more often in some regions. NGA FB01-00
- Exposed Coatings Need More: Vitro advises cleaning exposed coatings at least 3–4 times a year. Vitro TD-142
- Top Down, Out Of Direct Sun: Start at the top and avoid cleaning tinted or reflective glass in direct sun. NGA FB01-00
- Test First: Test clean a small area and inspect it in daylight before the full job. NGA FB01-00
Curtain Wall Systems
Insulating, laminated and decorative glass is glazed with sealants, gaskets and/or tapes. NGA warns that "glazing materials do not provide a sufficient barrier to prevent cleaning agents from entering the glazing pocket and damaging the edge of the glass product." NGA FB01-00 Cleaning methods on a curtain wall should limit solution running into joints.
Coatings And Special Glass
Find The Coating
NGA describes a pencil test: touch a pencil point to the glass. "If the reflection of the pencil point meets the real pencil, the coating is exposed on that side." A gap means the coating is not on that surface. NGA FB01-00 Damaging an exposed reflective coating can remove it and visibly change light transmittance.
Heat-Treated Glass
Tempered and heat-strengthened glass can carry surface fines and roller-wave marks from heat treating. These raise the risk of scratching when blades are used. NGA FB02-02 NGA advises against razors or metal scrapers in routine cleaning. NGA FB01-00
Rundown And Staining
Vitro calls out rundown from metals and masonry, such as concrete and stucco, as material to clean from glass. On heat-strengthened or tempered glass, it warns that "even a plastic scraper may dislodge" very small debris fused to the surface during heat treating and damage the glass. Vitro TD-142 Do not use acids. NGA FB01-00
Maintenance Schedule
| Practice | Guidance | Source |
|---|---|---|
| Routine Frequency | Generally Twice Per Year; More Where Needed | NGA FB01-00 |
| Exposed Coatings | At Least 3–4 Times Per Year | Vitro TD-142 |
| Sequence | Top Of Building Down | NGA FB01-00 |
| Sun | Avoid Direct Sun On Tinted/Reflective Glass | NGA FB01-00 |
| Tools | No Razors Or Metal Scrapers In Routine Cleaning | NGA FB01-00 |
| Trial Area | Test Clean And Inspect In Daylight | NGA FB01-00 |
NGA also lists "do nots": do not trap abrasive particles against the glass, do not let other trades lean tools against it, and do not let splashed materials dry on it. NGA FB01-00 On high-rise exteriors, WCBA coordinates rope or suspended access through a vetted partner crew.
Sources
- NGA/IWCA FB01-00 (2023), Proper Procedures For Cleaning Architectural Glass Products. agm-inc.com/images/Architectural_Glass.pdf
- NGA FB02-02 (2023), Heat-Treated Glass Surfaces Are Different. glass.org/sites/default/files/2023-10/…
- Vitro Architectural Glass TD-142, Glass Cleaning Recommendations. vitroglazings.com/media/ycnpjcpn/…
