Wood in interior spaces
Wood is hygroscopic. This means moisture moves in and out of wood depending on the building’s relative humidity (RH). The key to a stable wood ceiling, one without undue movement, is a controlled building environment. This is defined as being within a range of 25-55% RH.
An out-of-bounds environment can destroy the beauty and integrity of your wood ceiling.
Wood ceiling acclimatization is the process of your wood ceiling’s moisture content (MC) reaching stability with the RH of the environment. The point at which this happens is called Equilibrium Moisture Content, or EMC.
Wood is like a sponge. It even looks like a sponge under a microscope. It absorbs and gives off moisture constantly in response to the environment it lives in. Like a sponge it expands and contracts as it gains and loses moisture. With a sponge we don’t care what size it is as long as it gets the job done. With finished wood ceilings we do care because there is a risk of warp, unsightly reveals, or delaminated edge banding.
A controlled environment is defined as …
- Relative Humidity (RH) of 25-55%
- Temperatures between 55-85°F
These ranges are specified as parameters by the Architectural Woodworking Institute (AWI). An out-of-bounds environment can destroy the beauty and integrity of your wood ceiling.
Who is responsible for acclimatization?
9Wood. As the supplier, 9Wood is responsible to ship a wood product that meets the architect’s specification, and performs in a building that is maintained within a controlled environment, as defined in 9Wood warranty parameters.
Acoustical Subcontractor. The subcontractor is responsible to ensure the material is received, stored, acclimatized and installed in a controlled building environment. The subcontractor is the go-between that links 9Wood and the general contractor and is responsible to notify the GC and 9Wood if there is an environmental problem.
General Contractor. The GC is responsible to provide an installation environment that is controlled and stable. This means that the building is enclosed, the HVAC is up and running and the environment is stabilized within industry standards.
Architect. The architect is responsible to ensure that the wood ceiling is designed and specified with the realities of the building environment in mind (both area climate and building HVAC).
Owner. The owner is responsible to ensure that the building environment is maintained throughout the life of the wood product.
These roles track Architectural Woodworking Institute’s long-standing advisory entitled “Care & Storage: 1.4 Acknowledgments.” AWI sets the industry quality standards for architectural millwork across North America.
Because acclimatization requires the cooperation of so many parties, and can drastically affect the outcome of any wood ceiling project, we recommend that you download and familiarize yourself with our “Wood Ceiling Acclimatization for Professionals” handbook.