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Sizer performs rudimentary design for wood I-joists according to NDS Chapter 7 as described in Materials, I-joists. The program does not allow for wet service factor CM (7.3.3), beam stability factor CL (7.3.5), or preservative treatment (7.3.7). It does allow fire retardant treatment factors and temperature factor Ct (7.3.4). The repetitive member factor Cr (7.3.6) is not applicable to I-joists, having a value of 1.0.
These conditions imply that the I-joist is used in dry service conditions, is fully supported on the compression flange, and has not been treated.
None of the special design considerations other than the evaluation of shear at the support (7.4.7) and shear deflection (7.4.5) are implemented for I-joists. Bearing design (7.4.1), web stiffeners (7.4.2), Web holes (7.4.3), notches (7.4.4), load transfer blocking (7.4.6) are not considered in the generic version of WoodWorks Sizer.
Sizer implements shear deflections (7.4.5) by modifying the equations that increase deflection for simple span and loading conditions so they serve as an approximation for increasing the deflection from the finite element solution to any loading situation. In doing so, it uses the shear constant K value stored in the database for that product.
Many of these provisions are handled by customized versions of Sizer distributed by I-joist manufacturers.