Understanding Moisture Performance of Wood: Insights on Design and Construction Presented June 2015 by Ronald W. Anthony Disclaimer: This presentation was developed by a third party and is not funded by WoodWorks or the Softwood Lumber Board.
The Wood Products Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider #G516. Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-aia members are available upon request. This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
Course Description Understanding the effects of moisture on construction materials is important when designing high-performing, long-lasting buildings. This seminar reviews the response of both structural and finish wood products to various forms of water, and explains how relative humidity and liquid water can impact dimensional stability and durability. The discussion will include means of controlling wood shrinkage and swelling by considering pre- and post-installation environmental conditions and how to reduce the risk of decay. Learn appropriate design considerations for your projects and how to refine your specifications accordingly.
Learning Objectives 1. Review the interaction between moisture and wood as a building material. 2. Consider the effects of relative humidity and liquid water on wood products before and after construction. 3. Examine common wood-moisture issues observed in construction. 4. Discuss considerations for design and specifications to reduce the impact of moisture on the performance of wood products.
Wood is a biological material So what?
Wood behavior is highly variable!
It is that variability relative to use of wood in construction that we need to understand
Shrinkage and swelling Varies between species Is a function of change of moisture content Results in warp and checking
Decay fungi Food Moisture Oxygen Temperature
Molds, stains and mildew Molds and stains penetrate the surface of wood but do not reduce strength Mildew grows on the surface of wood and paint and do not reduce strength
Insects Borers tunnel through wood but do not eat it Bore holes contain frass Termites digest wood Bore holes are clean or contain pellets
Weathering of wood Moisture Ultraviolet light Abrasion
Durability Natural durability due to extractives Chemical preservatives Remedial treatments Finishes Detailing
Questions? This concludes The American Institute of Architects Continuing Education Systems Course Ron Anthony Anthony & Associates, Inc. woodguy@anthony-associates.com This presentation was developed by a third party and is not funded by WoodWorks or the softwood lumber check-off.
How do you make wood last?
How do you make wood last? KEEP IT DRY!
Factors affecting wood performance Moisture content Defects Durability Construction details Maintenance
Equilibrium moisture content Moisture content at which wood is in equilibrium with water vapor present in environment
Equilibrium moisture content Depends upon relative humidity Is always changing Affects wood performance
Where to look? Wood in contact with the ground Wood that exhibits moisture stains Wood with visible decay Roof penetrations, such as around chimneys and vents Attic sheathing, framing lumber, and timbers
Where to look? Material interfaces (beam pockets) Crawl spaces and basements Exterior woodwork, including cladding, shingles, and soffits Openings (doors and windows) Areas of the structure that have been altered
Engineered Wood Products Plywood Oriented strand board Glued laminated timber Laminated veneer lumber Products constantly being developed
Questions? This concludes The American Institute of Architects Continuing Education Systems Course Ron Anthony Anthony & Associates, Inc. woodguy@anthony-associates.com This presentation was developed by a third party and is not funded by WoodWorks or the softwood lumber check-off.
WOOD AND WATER Final Slide
Space for Brown Ledge Camp Photos
What goes in a specification? Species Dimensions Moisture content Grade Treatment
Design considerations Bending strength and stiffness Durability Aesthetics Wood species
32 Quincy Street Expansion and Renovation RPBW + P A Y E T T E
Design considerations Durability Dimensional stability Aesthetics Wood species
Questions? This concludes The American Institute of Architects Continuing Education Systems Course Ron Anthony Anthony & Associates, Inc. woodguy@anthony-associates.com This presentation was developed by a third party and is not funded by WoodWorks or the softwood lumber check-off.