Frequently Asked Questions
Search Options This page has been categorized for your convenience. The most efficient way to search this FAQ page is to use your browser's "Find" function. For Internet Explorer and Mozilla Firefox, use the Edit -> Find (Ctrl+F) function on the toolbar. You must have the tab open that contains the content you desire for this to work.
- Fire Performance and Design
- Wood Structural Issues
- Treatments / Preservatives / Adhesives
Fire Performance of Wood and Design
- Where can I find information on flame spread performance of wood products?
- Where can I find information on the design of fire-resistive exposed wood members?
- Where can I find information on fire rated wood floor and wall assemblies?
- Where can I find information on the Component Additive Method (CAM) for calculating and demonstrating assembly fire endurance?
- For one-hour fire-rated wood joist assemblies, how do I compensate using a 2x8 rather than a 2x10?
- Where can I find information on building construction and fire insurance costs?
- Where can I get information on firestopping and draftstopping for concealed spaces?
- Where can I obtain info on fire tests related to post-frame building design?
- Where can I find information on unprotected wood and steel joists exposed to fire?
- How do I calculate the fire resistance of exposed wood members?
- Where can I find information about fire tests of laminated wood and rolled steel beams?
- Where can I find information on the heat release rates of construction assemblies?
- Where can I find information on the performance of Finger-Jointed Lumber in Fire-Resistance-Rated Wall Assemblies?
- Is wood allowed in buildings classified as non-combustible per the International Building Code (IBC)?
- How do I meet the new requirement for membrane protection in the 2012 International Residential Code?
Wood Structural Issues
- Are there deflection limits for cantilevers?
- Where can I obtain information on construction tolerances?
- Where can I find information on wall bracing requirements at corners with openings?
- What is creep and how can I address it?
- How do I calculate a capacity for lumber sheathing or heavy timber decking diaphragms?
- What is the load duration factor (CD)?
- How do I design for notches in a bending member?
- Are there design values for shear perpendicular to grain?
- Are there span tables for cantilever beams?
- Where can I find criteria for vibration control for wood members?
- Where can I find information on designing wood frame structures for performance?
- Where can I find information on wood shrinkage?
- Is there a design method for increased buckling capacity of built-up wood beams?
- Does gypsum provide lateral support for wall studs?
- Per the 2005 NDS®, which Emin should be used for the design of an unbraced structural glued laminated timber column under purely axial load?
- NDS (2001/2005) Section 5.3.7 describes a specific loading scenario of "loaded parallel to the wide face of laminations" for application of the flat use factor, Cfu, for structural glued laminated timber. Does the flat use factor apply where eccentric column load induces moment in the y-y direction?
Wood Treatments, Preservatives, and Adhesives
- Where do I find more information about wood preservatively treated with Chromated Copper Arsenic (CCA)?
- How does fire retardant treatment (FRT) affect fire endurance?
- Where can I find publications on fire retardant treated wood?
- Where can I find information on mold and mildew of structural wood members?
- What are naturally durable species?
- Where can I find information on painting and finishing wood products?
- What are typical retention levels for treated wood preservatives used in construction?
- Does pressure-treated lumber have the same design values as lumber that is not pressure-treated?
- Where can I find information about preservation against termites?
- Where can I find additional background information for adhesives and epoxies used in wood construction?
- Where can I find information about corrosion of fasteners?
Green Building Design
Wood Products
- What is the difference between SPF and SPF south? DF-L and DF-L(N)? HF and HF(N)?
- Where can I find information for nominal 1", 1-1/4", and 1-1/2" stress-rated boards?
- Where can I find design values for cypress for structural use?
- Where do I find decking design values?
- Where can I find design values for lumber?
- Can finger jointed lumber (also known as end-jointed and edge-glued) be substituted for sawn lumber?
- Where can I find information on Lumber Grade Rules and Grade Stamps?
- Where can I find information about structural lumber grades vs. appearance characteristics?
- Where can I find design values, span tables, allowable load tables, and other information for structural softwood and hardwood lumber?
- What is the difference between plastic lumber and wood-plastic composites?
- What is the difference between southern pine and southern pine-misiones Argentina?
- Where can I find design values for tropical hardwoods, imported species, and other species not found in the NDS Supplement?
- Where can I find information on tongue and groove roof decking?
- How are the floor joist span tables calculated and used?
- Where can I get span tables and span table information for lumber?
Where can I get decking span tables?
Engineered Wood Products
- Where can I find information on fiber reinforced plastic (FRP) wood composites?
- Where can I find design values, span tables, allowable load tables and other information for structural glued-laminated timber?
- Where can I find information on glulam adhesive manufacturers?
- What are I-joists and where can I find them?
- Where can I find information on structural composite lumber (SCL)?
Panel Products
Wood Design Standards and Building Codes
- Why are the wind speeds in Minimum Design Loads for Buildings and Other Structures, ASCE 7-10 so much higher than those in ASCE 7-05?
- Where can I find information on federal specifications and standards for lumber and wood products?
- What are the design manuals for wood construction in high wind areas?
- What resources are available for wood construction in high seismic areas and why build with wood in earthquake-prone areas?
NDS
- What do the column headers for bolt design value tables 11 A-K in the NDS mean?
- Where can I find background on In-Grade Testing for the NDS supplement?
- Where can I find more information on all of the NDS references?
- What are the safety factors (factor of safety) that are used to derive allowable design values for wood fasteners, lumber design values, etc. referenced in the NDS?
- Why did shear parallel to grain (horizontal shear) design values increase in the 2001 NDS?
- If there's an existing structure where the MC<19% for southern pine timbers, could the designer back out the wet service adjustment from the NDS published design values in table 4D?
- For structural composite lumber (SCL), should the volume factor, CV, be applied to Fb* in calculation of the beam stability factor, CL, or is it intended that CV be applied following calculation of CL?
LRFD
- What is LRFD?
- What is the purpose of the NDS Format Conversion Factor, KF?
- For LRFD in the 2005 NDS®, why does the φ factor cancel out when adjusting nominal resistances using the LRFD Format Conversion Factor, KF , and the resistance factor, φ?
- For Load and Resistance Factor Designs (LRFD), many of the design examples and much of the discussion focuses on elastic stress analysis. I thought that one of the benefits of LRFD was its ability to accommodate plastic (non-linear) analysis. Why don't you cover plastic design considerations in your standards?
WFCM
Wood Technical Publications and Resources
- Construction Cost Saver Number 1-4
- Where can I find the video, House - Where, Why & How: a child's Guide to the Origins of Everyday Stuff?
- Where can I find bar code guidelines?
- How do I convert to metric lumber sizes?
- Where can I find information on installing wood and siding over foam sheathing?
- Where can I find information on architectural design of wood buildings in wet climates?
- Where can I find information on radon reduction?
- Where can I find technical papers on Timber Retaining Walls?
- Where can I find information on noise barriers?
- Where can I find span or load tables for beams, headers, and girders?
WSDD
Wood Connections and Assemblies
- What are the connection requirements for built-up beams?
- Where can I find information on flitch beams or composite wood members?
- Where can I find resistance values, connection details and other general information for bolts, lag screws, wood screws, nails, split ring and shear plate connections?
- Where can I find manufacturers of prefabricated wood connectors?
- Do you have information on toe-nail connections?
- Where can I find information on dowel bearing strength for plywood and OSB?
- How does the group action factor apply to connections? And Does the group action factor, Cg, apply to sill plates and ledgers?
- Are self-tapping lag screws covered by provisions in the NDS?
- What is the difference between full diameter and reduced diameter body lag screws (also known as lag bolts)?
- Where can I find referenced standards for dimensional tolerances for nails?
- Where can I find more information about the NDS reference, Square and Hex Bolts and Screws, Inch Series?
- Where can I obtain information on plywood gusset (gussett) plate connections and plywood gusset trusses?
- Where can I find design information for staples and/or pneumatic nails?
- Where can I find suppliers of timber rivets?
- Where can I find information on bracing of metal plate connected wood trusses?
- Where can I find information on wood dowel (wood peg) design values?
- Does the penetration depth factor, Cd, apply to design values for lag screws, wood screws, or nails?
- Where can I find information about designing anchor bolts per ACI 318 Appendix D and the NDS?
- The column heading for NDS® (2001/2005) Table 11.2A states that diameter for determining withdrawal design values is the "unthreaded shank diameter, D." Should withdrawal design values for reduced body diameter lag screws (see NDS Appendix L) be based on the reduced body diameter or the outside thread diameter?
Wood Building / Structure Types
- Where can I find information on log structures?
- Where can I find information on Timber Poles and Piles?
- Where can I find information on concrete formwork design and materials?
- Where can I obtain information on designing post frame structures (sometimes referred to as pole buildings or pole barns)?
- Where can I find information on timber bridge design and construction?
- What is timber frame construction and where do I find more information about it?
- Where can I find information on low-profile wood floor systems?
- Where can I find information on the structural performance of a house?
- Where do I find information on wood guardrails used in highway/bridge construction?
- Where can I find information comparing wood-frame and masonry structures?
- Where can I find information concerning metal plate connected wood trusses?
- Where can I find more information on bowstring trusses?
- Where can I find information on conventional wood frame construction?
- Where can I find information on plank and beam framing for residential buildings?
- Where can I find information on heavy timber construction?
- Where can I find information on evaluation, maintenance and repair of existing structures?
- What are the design criteria such as deflection limits and strength for wood guard rails or hand rails?
- What is Cross Laminated Timber?
- In a relatively active seismic zone, are heavy timber concentrically braced frames allowed? If so, what values (such as 'R') should be applied?
Permanent Wood Foundations
- Construction Cost Saver Number 5: The All-Weather Wood Foundation (PWF) (T35)
- What publications do you have on Permanent Wood Foundations?
- Can a conventional (solid) concrete footing take the place of the gravel footing for permanent wood foundations (PWF)?
Wood Energy, Thermal, and Acoustic Performance
- Construction Cost Saver Number 6: Keeping Energy Saving Construction Costs Down (T36)
- What is the thermal conductivity of wood and how does it compare to other materials?
- Is there any criteria as to length of building with wood products in which a thermal expansion joint is required?
- What are the thermal R-values for wood?
- What is the "Vented Air Space"?