2012 ASD/LRFD Manual for Engineered Wood Construction

16 M4: SAWN LUMBERTable M4.4-3Coefficient of Thermal Expansion, e TE , for Solid Woodse TESpecies Radial (10 -6 in./in./°F) Tangential (10 -6 in./in./°F)California Redwood 13 18Douglas Fir-Larch 1 15 19Douglas Fir-South 14 19Eastern Spruce 13 18Hem-Fir 1 13 18Red Oak 18 22Southern Pine 15 20Spruce-Pine-Fir 13 18Yellow Poplar 14 181. Also applies when species name includes the designation “North.”DurabilityDesigning for durability is a key part of the architecturaland engineering design of the building. This issue isparticularly important in the design of buildings that usepoles and piles. Many design conditions can be detailedto minimize the potential for decay; for other problemconditions, preservative-treated wood or naturally durablespecies should be specified.This section does not cover the topic of designing fordurability in detail. There are many excellent texts on thetopic, including AWC’s Design of Wood Structures forPermanence, WCD No. 6. Designers are advised to use thistype of information to assist in designing for “difficult”design areas, such as:• structures in moist or humid conditions• where wood comes in contact with concreteor masonry• where wood members are supported in steelhangers or connectors in which condensationcould collect• anywhere that wood is directly or indirectlyexposed to the elements• where wood, if it should ever become wet,could not naturally dry out.This list is not intended to be all-inclusive – it ismerely an attempt to alert designers to special conditionsthat may cause problems when durability is not consideredin the design.AMERICAN WOOD COUNCIL