Glass Block, The Ideal Rainscreen

As a building material, glass block is durable, sustainable, fireproof, and an excellent insulator. The material’s transparent nature offers superior energy efficiency while admitting light and muffling most of the sound from outside. By itself, as the primary cladding for new construction, glass block’s beauty and functionality have contributed to its growth as an essential building component throughout the world.

Because of its unique inherent qualities, glass block is also important in other, less traditional applications for construction. One unique application has been the implementation of glass block is rainscreens as an effective protect for buildings from driving rain and accumulated moisture.

What is a Rainscreen?

Accumulated moisture resulting from hard rains, ice, and snow is a significant threat to any construction. As moisture penetrates the outer cladding, it tends to accumulate within the walls without draining or evaporating. As a result, the wall substrate of the structure weakens and speeds up deterioration and structural problems.

Concrete and brick are highly permeable materials and are prone to moisture penetration and accumulation beneath their exterior surfaces. The mortar joints of these materials are typically plaster and will crack or separate over time, also creating a path for moisture to penetrate.

Wood siding often cracks from temperature changes and freeze-thaw cycles, thereby leaving gaps for moisture to gain entry. Also, exterior walls are most vulnerable at junctions around windows, doorways, and eaves that are not adequately sealed.

Natural building movement and settling will also create cracks and separations that can admit moisture.

To counter adverse effects of moisture penetration, builders are applying glass block rainscreens that constitute an additional exterior layer separated by a small gap or airspace. The glass block rainscreens’ spacing is designed to provide a capillary break that allows drainage and evaporation if moisture should penetrate the exterior surface.

While most rainwater will merely bounce off, as in the case of a glass block exterior cladding, the rainscreen exterior surface breaks the force of sideways, wind-driven water movement, so that any water that gets through breaches in the surface has lost its momentum.

How Does the Glass Block Rainscreen Work?

Creating a completely watertight building with most materials is virtually impossible without employing some offsetting strategies. The objective of effective glass block rainscreens is to create an envelope that keeps moisture from penetrating beneath the primary cladding into the inner wall structure. Glass block rainscreens should be installed to allow a gap, approximately 1/8” to let gravity drain moisture away to flow easily downward without contact with the inner cladding. Weep holes must be added at the base of the structure to allow moisture to escape entirely.

In many cases, further protection can be achieved by adding a weather-resistant barrier layer beneath the glass block rainscreens to further repel any stray drops.

Why Protect with Glass Block Rainscreens?

Draining downward and away from the inner surface assures that the moisture will not reach the less durable wall assembly structure within. The extra layer and gap act as a raincoat by keeping everything within completely dry. Allowing the moisture to escape or evaporate without lingering within the walls is crucial.

Durable glass block is an ideal option for protecting any building. Because moisture does not penetrate glass block, the material can be used for many exterior applications. And, unlike pane glass, condensation does not occur either. As a result, tightly sealed glass block is very popular for basement windows that are extremely vulnerable to accumulated snow and water.

Architects around the world are using glass block as the primary exterior material for the world’s unique and beautiful structures. Glass block is beautiful, energy efficient, and prevents water penetration and leakage. Once installed, there is virtually no space between the individual units. The blocks are joined with a specially designed mortar or silicone material that does not crack and is water resistant.

The Versatility of Glass Block

Glass block is non-conductive, water repellent and, because of its transparency, light admitting material. These properties make glass block the most energy efficient building material available, ideal for glass block rainscreens.

The same durability and water resistant properties that work well for glass block rainscreens construction allow glass block to work well for interior walls, floors, and stairways.

Contact GBA Architectural Products & Services

A leader in supplying glass block and related materials to builders and contractors throughout North America, GBA Architectural Products & Services has provided materials and installation for building interiors and exteriors since 1985. Thoroughly committed to the advantages of glass block construction, GBA has collaborated on many high-profile construction projects for diverse clients. Some of these may be viewed in the GBA Case Studies website:

  • Hecht Warehouse at Ivy City in Washington D.C.
  • St. Anne’s Warehouse in Brooklyn, N.Y.
  • Puck Building in New York, N.Y.
  • Howard Young Correctional Institute in Wilmington, Delaware
  • 21C Museum Hotel in Oklahoma City, Oklahoma
  • Stillwell Avenue Station, MTA, New York, N.Y.

As shown, glass block offers broad and diverse applications for construction.

To witness more information about glass block construction for existing or new buildings, visit the GBA Architectural Products & Services website to understand the advantages of this material.

Or, to learn more about glass block rainscreens and other applications from the experts at GBA Architectural Products & Services, phone one of GBA’s regional offices at:

  • Midwest: (877)-280-7700
  • East Coast: (212)-255-5787
  • West Coast: (213)-634-7050