Track 2: Materials over Time: Points of Change
1 - Specifying Wood: Reconciling History, Changing Ecosystems, and the Lumber Industry
Wednesday, September 26
10:30 AM - 12:00 PM
Location: HYATT-Grand EFG
Building Conservation Associates, Inc.
Specifying Wood: Reconciling History, Changing Ecosystems, and the Lumber Industry
Through the execution and the bidding of hundreds of projects, I have read specifications for the use of wood in historic structures from dozens of architects, engineers, and other preservation professionals. Rarely are those specifications very useful, as they stand written.
This paper will provide a knowledge base with which to write wood specifications that will meet the design criteria of performance in use, durability, and authenticity. Furthermore, it will provide the basis to create specifications that can be met by contractors, as well as the information necessary to evaluate contractor- proposed alternatives.
Throughout history the availability of different species of lumber has been ever evolving and changing. This is true today more than ever. The performance and visual characteristics of many species has changed over time. Our dependence on both the historical record and extant evidence in determining the choices of woods for a project can sometimes run counter to the desired design objectives. A specification “to match original species” may not be achievable, nor desirable. The wood may no longer be commercially available or the characteristics of old growth and second, third and fourth growth timber may be drastically different.
Most preservation professionals rely on and build from their specifications for previous projects. This is generally a good practice, however, the reuse and adaptation of previous wood specifications fails to account for both the continually changing lumber industry and the volatility of the imported wood market. What seemed a sound choice even a couple of years ago, may be unavailable, unsustainable, or less desirable due to updated performance information. The search for responsibly harvested durable wood for restoration work can become a continual research project.
It is important for preservation design professionals to understand the domestic, foreign, and salvage supply chains for building lumber. It is equally important for them to understand the basic physical characteristics of wood, as well as the sources of wood technology research. This knowledge should be the foundation for developing the performance and authenticity criteria for each project, making appropriate compromises when necessary, and writing useful and accurate specifications.
- Understand the difficulties of specifying lumber for historic projects
- Clearly set the design priorities regarding wood to be used in a project
- Know how to evaluate or find information to help evaluate different species of lumber for various uses.
- Write a clear, concise, accurate, and achievable specification for wood in historic projects