GENERAL DESCRIPTION

Spandrel Glass is glass that has been rendered opaque. Silkscreened Glass can be transparent, translucent, or opaque. The primary difference between Silkscreened glass and Spandrel glass is the method of application of the paint material.

The primary purpose of spandrel glass is to mask materials or construction from view from the exterior of the building. Areas above suspended ceilings or below the vision line in the knee-wall area are typically hidden using opaque materials. Vertical spandrels are sometimes used to hide an interior partition or a column in what is normally a vision glass band.

Silkscreened glass can be used to partially obscure glass for light or vision control. Painting the full surface of the glass with a silkscreen translucent ceramic enamel is used to obtain diffused light transmission. Silkscreened glass can be used in conjunction with a full coverage spandrel paint to obtain a patterned opaque spandrel area.

MATERIAL OPTIONS

When designing the exterior skin of a building the design architect has several choices of materials to use for the opaque (spandrel) areas. In curtain wall construction the exterior skin of the building is often comprised of 50 percent or more of opaque wall construction. Modern aluminum curtain walls have all but replaced load bearing masonry construction for nonresidential buildings; the non vision areas of a building have been made of many different types of material. Architects have used metal panels, precast concrete or thin slabs of marble or stone, but glass spandrel panels are the most durable and economical products. Several buildings which used thin slabs of granite or other types of cut stone have experienced structural problems because of the failure of these thin slabs of stone due to weathering after less than 15 years. The smooth, impervious, homogeneous surface of float glass is also more dirt, stain and corrosion resistant than most other spandrel materials. Glass in spandrel areas eliminates concern about corrosion and many other types of deterioration that may occur with other types of building materials.

DESIGN CONSIDERATIONS

From a design concept the architect has several choices in his treatment of the opaque areas of the exterior skin of the building. Many designers wish to make the whole exterior of the building appear uniform. Other design concepts use contrasting vertical or horizontal striping or banding with the spandrel material to make their visual statement.

When attempting to make the exterior of a building uniform in appearance the architect must consider not only the color, but also the optical properties of the vision area glass. Even when the vision glass has been coated to become highly reflective, sunlight will not be reflected back to the exterior observer with exactly the same intensity in the opaque areas as in the vision areas. A balanced homogeneous appearance can be achieved during much of the day, but at dawn and dusk, horizontal and vertical banding WILL occur because of the differing exterior and interior light intensities. Using reflective glass with the highest amount of outdoor reflectance will minimize this banding effect, it cannot be totally eliminated. A visual mock up at the proposed building site, oriented to match the curtain wall facade, is essential for the designer to properly visualize the completed building appearance. The degree of interior illuminance of the coated glass is also affected by light levels which exist in the building interior versus the spandrel area. Curves and articulation of the wall can be used to alter the appearance of the glass facade as well as create a different visual reflectance.