Design Solutions - Summer 2013 - (Page 7)

and owners in Section 2 – Care and Storage. Having lived and worked in the humid Southeastern U.S., I know and understand first-hand the effects that moisture can have on wood. Stability and consistency in the environment is the key to success. If wood is installed in an environment that is consistently at 50% relative indoor humidity and that environment is maintained with no wide swings in humidity, then the woodwork will not have as much opportunity to gain or lose moisture and thus will not be as prone to dimensional movement. The same goes for an installation in an arid climate where the indoor relative humidity may be 20%. As long as there are no wide swings in indoor relative humidity, the woodwork will remain relatively stable. Now let’s explore an installation scenario where woodwork problems often arise due to climate control. Houses of worship are often places where Premium Grade millwork including wall paneling, casework, and wood decorative elements are displayed. However, the public assembly spaces are often unoccupied for the majority of the week with HVAC systems that operate on timing devices in order to save energy. This scenario can be very detrimental to woodwork installed in such an environment. In the summer months, the humidity is traditionally higher throughout North America. In these conditions without dehumidification provided through the buildings mechanical systems, the woodwork will tend to absorb moisture and expand. Then, a few hours or perhaps a day prior to a worship service, the HVAC system will be turned on, the air conditioning will run, and the relative humidity will drop for a 24 to 48 hour period causing the woodwork to begin to dry and contract before the HVAC system turns off, the humidity climbs, and the woodwork expands for days between the next cycle. The higher humidity of summer brings about swelling doors and panels which will bind or buckle if not given the proper room to expand. The cyclical swelling and shrinking above also serves to loosen joints and fasteners much like the motion of bending a paperclip – it’s only a matter of time before something “breaks”. Take the same scenario in the winter months. While the indoor relative humidity is not as high as in summer, when HVAC systems begin to heat buildings, this causes a drying effect and deprives the woodwork of the moisture that it needs to maintain stability. If the drying occurs in a rapid fashion, this can cause issues such as cracking of solid wood members, the bubbling, buckling, or blistering of veneers as the cores contract, opening of miters and joints in trim members, and doors will display larger gaps around the frame members. These are only a few of the issues that may be evident due to wide swings in temperature and humidity. Finally, there are a few key points to keep in mind during the changing seasons and the resulting changes in indoor climate control: Wood moves – anticipate the changes. Balanced construction techniques, proper design, material choices, proper finishing, preinstallation acclimation, and user care and maintenance can all help to mitigate this movement but nothing can eliminate it. Don’t be pennywise and dollar foolish. Explore methods of maintaining the indoor relative humidity of the spaces where interior architectural millwork is installed. This may mean installing and operating humidifiers/de-humidifiers during different times of the year rather than fully heating or cooling spaces. Maintaining the aesthetic and functional properties of your interior woodwork does have a cost, but so does the replacement of unsightly damage caused by poor climate control. Allow for acclimation. Gradual change from one relative humidity to another allows for the woodwork to respond uniformly, thus mitigating some of the effects of dimensional change by letting the components move and settle. This is particularly important when new millwork transitions from the shop where it was fabricated to the jobsite where it is to be installed. It is extremely important that the installation environment be as close to the finished and occupied building environment as is possible. Woodwork should never be installed while the HVAC systems are not running properly, there is still wet work in progress, or there are large openings to areas without climate control. Once cut, fit, and installed, there is no “board stretcher” to close up the open joints or gaps that may occur should there be a drop in relative humidity after installation. In a world where contractors often rush the millwork acclimation and installation process in order to meet a looming deadline, a few extra days wait for the installation environment and the woodwork to acclimate prior to installation will prevent many issues from occurring. Have technical questions? Contact Ashley Goodin, AWI Technical Services Manager at 229-942-1004 or at agoodin@awinet.org. summer 2013 I design

Table of Contents for the Digital Edition of Design Solutions - Summer 2013

Design Solutions - Summer 2013
Contents
Cornerstone
A Global Icon
Designed for Growth
A Delicious Design
HUB of Activity
Digital Measurement: Working on A Curve
Product Showcase
AWI Manufactoring Members
Ad Index
AWI Supplier Members

Design Solutions - Summer 2013