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Lumber DesignEasy Installation & Uses

Note: To update your version of WWPA Lumber DesignEasy - Joists or Design Easy - Beams, download the new version from the WWPA web site and follow these instructions. The new files will replace the old files in the C:/WWPAEZJoist or C:/WWPAEZBeam directory on your computer.

Download Lumber DesignEasy here.

The WWPA Lumber DesignEasy program will install automatically on your hard drive and place icons in your Start Programs list and, if you prefer, on your desktop.

To install, download the DESIGNEZJoist.ZIP and/or DESIGNEZBeam.ZIP files to your PC. Double-click the .ZIP files then select the DESIGNEZJoist.exe or DESIGNEZBeam.exe file. Click OK and follow the instructions on the screen. The installation will create the directory C:\WWPAEZJoist or C:\WWPAEZBeam on your hard drive, copy all the files needed for and add icons to your Start Program list and, if you prefer, your desktop.

YOU MUST HAVE MICROSOFT EXCEL INSTALLED ON YOUR DEVICE IN ORDER TO RUN WWPA LUMBER DESIGNEASY.

For common issues in installing Lumber DesignEasy, go to the FAQ page.

Operating WWPA Lumber DesignEasy - Joist and DesignEasy - Beam programs

The WWPA Lumber DesignEasy programs calculates simple Western lumber spans for joists and rafters and for beams with uniformly distributed loads. It is optimized so it can be used on a portable device. Users select the species, size, dead load, live load, load duration factor, span deflection limit and incising status for pressure-treated wood. Lumber DesignEasy then generates a span table for all appropriate structural grades for that species group.

DesignEasy - Joists/Rafter Spans

The DesignEasy - Joists program will create floor joist and rafter span tables for structural grades in the major Western species based on the size of the lumber and commonly used load and use parameters. To generate a span table, users may enter values indicated in blue.

To allow the DesignEasy program to work on PDAs, the cells have not been protected. As such, it may be possible to inadvertently change or overwrite a cell that may impact the calculations. If cells other than those marked in blue are changed, the calculated spans may be incorrect. To reset the program to its default values, follow the instructions shown in the FAQ.

Entering lumber and loading information

The DesignEasy program features individual worksheets for six major Western species groups: Douglas Fir-Larch (DF-Larch), Douglas Fir-South (DF-South), Hem-Fir, Spruce-Pine-Fir South (SPF-South), Western Cedars (W. Cedars) and Western Woods (W. Woods). To select a species group, click on the appropriate tab at the bottom of the worksheet.

Users may change seven different loading parameters to generate joist and rafter span tables. Each of these seven parameters are limited based on available products or common design considerations. The potential selections are:

Lumber Thickness - Spans are calculated for only nominal 2 or 3 inch thick lumber. Entering thicknesses other than 2 or 3 will generate an error message: Warning! -> Size NGindicating the size is no good.

Lumber Width - Spans can be calculated for widths in 2-inch increments from 4 to 16 inches. Entering width under 2 inches, over 16 inches or in other than 2-inch increments will generate an error message: Warning! -> Size NG, indicating the size is no good.

DL or Dead Load - This is the weight, in pounds per square foot (PSF), borne by the structure from construction materials such as joists and structural wood panels. While any number can be entered, the typical values are 1020 or 25 PSF.

LL or Live Load - This is the weight, in pounds per square foot (PSF), borne by the structure from the presence of mobile objects such as people, furniture or items moved in or out of the structure. While any number can be entered, the typical values are 30405060,7580100 or 125 PSF.

Incised? - Incising is a process of cutting slits into the lumber. This is used for Western lumber products that are preservative treated. Incising will reduce the structural capabilities of the lumber. If the lumber is not incised, leave the value at N for No. If the lumber is incised, change the value to Y for Yes.

CD or Duration of Load - Lumber can carry substantially greater loads for short periods of time and this value adjusts spans for the likelihood of certain short durations loads. Three values may be entered: 1.0 for normal duration floor loads, 1.15 for rafters with snow loads and 1.25 for rafters with roof minimum live loads. Entering values other than these three selections will generate an error message: Re-Input CD and CD NG, indicating the Duration of Load entered is no good.

LL L/Def or Span/Deflection Limit - Structural members bend, or deflect under load and deflection is limited based on use. Three values may be entered: 360 for floors or ceilings with plaster, 240 for drywall ceilings or rafters and 180 for rafters with no finish. Entering values other than these three selections will generate an error message: Re-Input LL L/Def and LL L/Def NG, indicating the Span/Deflection limit entered is no good.

DesignEasy - Beams/Headers Spans

The DesignEasy - Beams program creates beam span tables for both solid-sawn timber and built-up Dimension lumber beams and headers in Douglas Fir-Larch and Hem-Fir based on the size of the lumber and commonly used load and use parameters. To generate a span table, users may enter values indicated in blue.

To allow the DesignEasy program to work on some portable devices, the cells have not been protected. As such, it is possible to inadvertently change or overwrite a cell that may impact the calculations. If cells other than those marked in blue are changed, the calculated spans may be incorrect. To reset the program to its default values, follow the instructions shown in the FAQ.

Entering lumber and loading information

The DesignEasy - Beams program features individual worksheets for Douglas Fir-Larch (DF-Larch) and Hem-Fir (HF) in both solid-sawn timber beams and built-up 2-inch Dimension lumber beams. To select a species group and beam type, click on the appropriate tab at the bottom of the worksheet.

Users may change seven different loading parameters to generate beam and header span tables. Each of these seven parameters are limited based on available products or common design considerations. The potential selections are:

Depth - Spans for built-up Dimension lumber beams are calculated for 2-inch thick lumber in depths from 4 to 18 inches. Solid-sawn timber spans are calculated on thicknesses of 6 to 14 inches and depths of 6 to 24 inches.  Entering depth other than 4 to 18 inches for Dimension lumber or 6 to 24 inches for timbers will generate an error message: Warning! -> Size NGindicating the size is no good.

D Load or Dead Load - This is the weight, in pounds per square foot (PSF), borne by the structure from construction materials such as joists and structural wood panels. While any number can be entered, the typical values are 1020 or 25 PSF.

L Load or Live Load - This is the weight, in pounds per square foot (PSF), borne by the structure from the presence of mobile objects such as people, furniture or items moved in or out of the structure. While any number can be entered, the typical values are 304050,607580100 or 125 PSF.

Trib Width or Tributary Width - This is the average width of the loaded area the beam member is carrying. Values are entered in feet and the fractional equivalent of inches. For example, the tributary width of 8 feet, 6 inches would be entered as 8.5

Incised? - Incising is a process of cutting slits into the lumber. This is used for Western lumber products that are preservative treated. Incising will reduce the structural capabilities of the lumber. If the lumber is not incised, leave the value at N for No. If the lumber is incised, change the value to Y for Yes.

CD or Duration of Load - Lumber can carry substantially greater loads for short periods of time and this value adjusts spans for the likelihood of certain short durations loads. Three values may be entered: 1.0 for normal duration floor loads, 1.15 for rafters with snow loads and 1.25 for rafters with roof minimum live loads. Entering values other than these three selections will generate an error message: Re-Input CD and CD NG, indicating the Duration of Load entered is no good.

LL L/Def or Span/Deflection Limit - Structural members bend, or deflect under load and deflection is limited based on use. Three values may be entered: 360 for floors or ceilings with plaster, 240 for drywall ceilings or rafters and 180 for rafters with no finish. Entering values other than these three selections will generate an error message: Re-Input LL L/Def and LL L/Def NG, indicating the Span/Deflection limit entered is no good.

Printing span tables

When used on a PC, Lumber DesignEasy can be used to create printed span tables. Click on the Print icon in the upper right corner for a printed copy of the span table that appears on your screen.