Building Exterior, Expansion And Contraction Issues

Property owners, building management, engineers and architects are plagued with the issue of expansion and contraction within a building. Regardless, whether the building is a commercial, industrial or residential structure, the edifice is constantly expanding and contracting related to the ambient temperature. As the temperature rises the building expands, temperature decreases the building contracts. When using different type materials, the building components will expand and contract at different rates. Concrete, brick, masonry block, steel, wood, vinyl and plastic, each have a different rate of movement. Dissimilar materials can have extensive affects on joints over long periods of time.

To best describe how a typical building expands and contracts, imagine a dry sponge representing the exterior of the structure. The dry sponge is at its absolute contraction point. Saturating the sponge; it allows the sponge to swell to its absolute expansion point, in all directions. As the moisture is released from the sponge it maintains a median state when the ambient temperature hovers around 70 degrees. The ambient temperature rises the building expands, the ambient temperature decreases the building contracts. So ask yourself, how does the expansion and contraction of a building affect the building components?

Typically, engineers and architects take in consideration of this movement process when designing structures. Expansion joints are utilized to compensate for the expansion and contraction of the edifice. Expansion materials are placed within the joint to seal against moisture intrusion. Unfortunately, this is a component that requires maintenance every 5 to 7 years. However, the design team fails to consider the exterior coating components, such as the painting system. The exterior wall expands in all directions, which requires the paint material to expand at the same rate as the substrate. If different materials are utilized to construct the exterior wall, each material will expand at a different rate requiring a joint to separate the various materials. Therefore, whenever two materials meet on the exterior façade a joint should be provided to separate each material.

The joint systems utilized on building exteriors consist of various materials; rubber, silicone, urethane and metal. Typical construction practice is to install the joint sealant or expansion joint material as the exterior façade in erected. The exterior color, in the form of paint, is installed over the exterior façade during construction. When installing paint products over a silicone material during construction, than failure will occur. Typical paint products do not bond to silicone materials. Once a failure occurs within the painted surface moisture will infiltrate the exterior façade causing further failure of the painted surface. In addition, typical paint products are unable to expand and contract at the rate of the substrate that it’s applied over; thus causing failure within the painted surface. Reducing the longevity of the paint protection to the building envelope.

Technology has developed various systems that can alleviate the problems that occur during design and construction; provide the moisture protection and the longevity expected by property owners. These exterior components are capable of handling the expansion and contraction requirements of the various materials. Expert exterior contractors are familiar with the various products and systems. When properly installed the building envelope will continue to provide the protection required for over 30 years. Ultimately, this reduces the maintenance budget for the building owner, reduces moisture infiltration and reduces the possibility of mold growth.