Quick answer: Spandrel glass is opaque architectural glass installed in curtain walls and window walls at slab lines, between floor levels, to conceal interior structure (slab edges, ceiling cavities, mechanical chases) from the building exterior. It comes in two main types: ceramic-frit spandrel (color baked onto the back surface of glass) and shadow box spandrel (a vision lite with an opaque panel behind it).
In a multi-story curtain wall, the vision area of each floor (where occupants look out) is separated from the next floor's vision area by a spandrel zone. The spandrel zone covers the slab edge, perimeter mechanical, ceiling cavity, and any architectural feature you don't want visible from the building exterior. Typical spandrel zone height: 24-48 inches.
Ceramic-frit spandrel is a single lite of glass with opaque ceramic ink fired onto the back (interior-facing) surface. The frit pattern is typically solid (100% coverage) on spandrel — though dot-pattern and gradient frit are used for special applications. Frit colors are typically warm-neutral, dark-neutral, or color-matched to the architectural design intent.
Shadow box spandrel uses a vision lite (clear or low-E) with an opaque insulated panel (typically painted aluminum or color-matched material) installed behind the glass at a 6-12 inch setback. The result: a deeper, dimensional appearance with shadow lines visible inside the spandrel. More expensive than frit but offers a higher-end architectural look.
Spandrel glass typically must be heat-strengthened or fully tempered because the spandrel zone experiences thermal stress (sun heats the opaque back surface, glass tries to expand). Heat-strengthened is standard for most spandrel; fully tempered is required where building code specifies safety glazing or where the spandrel is at hazardous-location height.
Ceramic-frit spandrel costs roughly 30-50% more than equivalent clear vision glass. Shadow box spandrel costs roughly 60-100% more. The cost driver is mostly fabrication (frit firing or panel installation) rather than glass cost itself.
Frit color selection is best done with physical samples in actual daylight. Computer renderings consistently misrepresent how frit colors read on the building. Get 12x12 inch field samples and view them at the actual building site at noon and at 4pm before committing to a color.
Spandrel glass is opaque architectural glass installed in curtain walls and window walls at slab lines to conceal interior structure (slab edges, ceiling cavities, mechanical) from the exterior. It's used between floor levels to separate vision-glass zones.
Vision glass is transparent and used at floor-occupied levels for daylight and view. Spandrel glass is opaque and used at slab lines and floor-line zones to conceal the building structure. Both are part of the same curtain wall assembly.
Spandrel glass typically must be heat-strengthened (or fully tempered) because the opaque back surface heats up in direct sun and creates thermal stress. Heat-strengthened is standard; full tempering is required in safety-glazing locations.
Ceramic-frit spandrel uses opaque ceramic ink fired onto the back of a single glass lite. Shadow box spandrel uses a vision lite with an opaque panel installed 6-12 inches behind it, creating dimensional depth. Shadow box costs more but offers a higher-end appearance.
Yes — ceramic-frit can be matched to virtually any architectural color, including custom RAL or Pantone-equivalent specs. Solid frit, dot-pattern, and gradient frit are all available. Always review physical samples in daylight before committing.
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