Maximum Span Calculator for Wood Joists and Rafters

Span Calculator

(Web-based version)
Performs calculations for ALL species and grades of commercially available softwood and hardwood lumber as found in the NDS 2012 Supplement. Joists and rafter spans for common loading conditions can be determined. A "span options" calculator allows selection of multiple species and grades for comparison purposes.
Connection Calculator

Connection Calculator

(Web-based version)
Provides users with a web-based approach to calculating capacities for single bolts, nails, lag screws and wood screws per the 2015 NDS. Both lateral (single and double shear) and withdrawal capacities can be determined. Wood-to-wood, wood-to-concrete, and wood-to-steel connections are possible.
TR15 Acoustic Calculator

Based upon the data and methodologies compiled in American Wood Council's Technical Report No. 15 (TR15), this calculator simplifies the calculation of sound transmission through wood-frame floor and ceilings. Sound transmission class (STC) and Impact insulation class results are given as well as the following detail data at ⅓ octave band center frequency ranging from 125 Hz to 4000 Hz:


  • Floor Layer Estimated Transmission Loss
  • Ceiling Layer Estimated Transmission Loss
  • System Effect
  • Estimated Transmission Loss
  • ASTM E413 Reference Contour
  • STC shifted Reference Contour
  • Estimated Transmission Loss Deficiencies


  • STC Transmission Loss
  • ISPL Adjustment
  • Estimated Impact Sound Pressure Level
  • ASTM E989 Reference Contour
  • Shifted Reference Contour
  • Impact Insulation Deficiencies
Energy UA Calculator
Calculates an opaque wall or fenestration U-factor based upon the Total UA alternative compliance method permitted by the International Code Council’s 2012 International Energy Conservation Code (IECC) or International Residential Code (IRC). This new Energy UA Calculator is consistent with AWC’s Design for Code Acceptance 7, “Meeting Residential Energy Requirements with Wood-Frame Construction.” For use with the 2012 IECC or IRC, the AWC Energy UA Calculator app also gives insulation requirements needed in various wood wall assemblies to achieve the specified opaque wall U-factor. Wall assembly configurations calculated by the app include 2x4 and 2x6 wood framing at 16” and 24” on-center spacing as well as several cladding and sheathing options.
Heights & Areas Calculator

The Heights and Areas (H&A) Calculator is a joint effort of the American Wood Council, WoodWorks – The Wood Products Council, and the International Code Council (ICC). It provides users with an app-based approach to calculating maximum heights and areas for buildings of various occupancies and fire protection based on 2006 to 2015 editions of ICC’s International Building Code® (IBC®) provisions. Input a given building geometry, site conditions (e.g., open frontage), type of construction and occupancy, and allowable heights and areas can be determined. Links to download Android, iOS and MS Windows versions are shown on this page.

This H&A Calculator is not meant to be a replacement for the IBC and does not encompass all of its design options. The IBC should always be consulted for final construction type determination, in addition to state and local amendments to the IBC that may apply.


Carbon Calculator
Wood products continue to store carbon absorbed by the trees during their growth cycle, keeping it out of the atmosphere indefinitely. Using wood in place of fossil fuel-intensive materials also "avoids" greenhouse gases that would have been emitted during manufacturing. Now, it is possible to quantify these benefits for wood buildings.
WoodWorks® Software For Wood Design

Use WoodWorks® to quickly design components of light-frame and mass timber structures. Conforms to IBC, ASCE 7, NDS and SPDWS. WoodWorks® offer three programs:

  • Sizer – For beam, joist, columns, wall stud and CLT design
  • Shearwalls – For wood and gypsum board sheathed walls
  • Connections – For wood-to-wood, wood-to-concrete, and wood-to-steel connections