Designs for Healthy Building Envelopes

Words: Dan Kamys

By Alice Muratore

A multi-unit residential building in the Seattle, Wash., area. Castia Stone siding was installed for rain protection and classic architectural values.
A multi-unit residential building in the Seattle, Wash., area. Castia Stone siding was installed for rain protection and classic architectural values.
Stone: capital detail used at the top of a fluted column.
Capital detail used at the top of a fluted column.
Keystone with curved edges and detail on the face.
Keystone with curved edges and detail on the face.

Taking a page directly from the “How to Effectively Combine Aesthetics and Function” manual, some innovative, new masonry products have successfully addressed industry concerns about moisture damage with traditional siding products. A few of these concrete products blend the classic and elegant craftsmanship of European design with patented technology to make a product that not only looks great, but also is environmentally conscious.

According to the National Association of Home Builders (NAHB), the majority of residential construction defect claims in the past have been related to moisture issues: “In March of 1999, the NAHB Research Center listed the most common problems they found that were associated with water intrusion … as being: Windows, Doors, Electrical Outlets, Roof Flashings, Deck Flashings, Below Grade Installations, and Vents.”

The NAHB-commissioned study went on to state: “… homes surveyed ages two to six are experiencing structural damage due to excessive moisture buildup within walls. The cause of the moisture accumulation is rainwater intrusion from a combination of factors including: improper sealing at joints and around windows, doors, and other penetrations; improperly sloped horizontal surfaces …”*

Some traditional siding materials, such as manufactured stone, EFIS, and stucco, can trap varying levels of moisture behind the product that can potentially lead to dry rot, mold and deterioration of structural materials. To illustrate this point, one independent article stated: “In a group of randomly tested homes … fully 95% were found to have some moisture problems, with the resulting damage estimated to average $3,000 to $5,000. … Some of the design or installation changes that may help stem further losses include … the use of “rain screen” or “pressure equalization” venting technologies, to vastly reduce water infiltration tendencies …”**

Allowing trapped moisture to escape the cladding is essential to having a healthy building. Masonry products with rain screen technologies often will provide at least half an inch of space between the exterior siding and the structural wall material, which promotes air circulation and serves as a drainage channel.

While some new products have sought to limit trapped moisture via embedded systems within the mortar used as the mechanism for attachment, other products have completely eliminated the need for mortar, and therefore dramatically reduce the exposure to the effects of moisture within the exterior wall structure. Bottom line: less mold and mildew in the wall.

Castia Stone Slate Tiles, moldings, and fluted columns gave this home architectural detail and elegance.
Castia Stone Slate Tiles, moldings, and fluted columns gave this home architectural detail and elegance.
Light block resting on Slate Tiles.
Light block measuring 8"W x 12"H resting on Slate Tiles.

Products like Castia Stone’s rain screen technology utilize an engineered bracket system made from recycled materials or galvanized steel, depending upon the application. Their patented reinforced bracket is attached to the structural wall with screws – no mortar needed. Because this type of masonry product is a mortar-less system, moisture has nowhere to remain in the wall and, given the spacing, permits enough airflow to all the moisture to evaporate before causing structural damage. These types of concrete cladding systems provide a healthy building envelope that will minimize mold and mildew in the wall structure. The rain screen actually makes the building perform better since it can breathe, and vent moisture without having a detrimental impact on the exterior of the building and all the wall structure behind the cladding.

Another advantage of these mechanically fastened cladding systems is that they can be installed in any weather and don’t require any of the preparatory systems like lath and scratch coats to be in place prior to installation. This also affords easier jobsite cleanup and the disposal of waste materials is greatly reduced. These types of innovative products are environmentally friendly – both in the product itself, plus in the installation process.

Many of these mechanically fastened cladding systems can be installed virtually anywhere other mortared siding or cladding products are installed, both exterior and interior. These products have successfully been installed on all types of projects including residential, commercial, institutional, and military housing. Most manufacturers offer several unique textures and dimensional offerings within their product group.

Some producers also offer their fastening technology in architectural moldings that naturally compliment any traditional masonry façade. These products are built around the same rain screen offset of 10 mm or 1/2-inch and install with the same ease as the cladding.

A number of these manufacturers have drawings available for download on websites, such as, in both PDF and DWG formats, which are perfect for designers and architects alike.

If on your next project you are looking for a concrete masonry cladding that is beautiful in appearance, environmentally friendly, technologically superior, and cost-effective to install, one of these systems might be a great fit.

Homeowners looking to build or remodel will find these products to be a fantastic new option, while homebuilders and remodeling contractors will really appreciate the look and ease of installation. For the designer, these thin masonry cladding systems provide the architect with a strong, durable, and creative material that can be used in combination with traditional sidings, and provide luxurious and greatly enhanced building designs.

Alice Muratore is CEO of Castia Stone Inc. Visit





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