Now consider the same floor joist supporting stone tile flooring, such that floor dead load is now 20 psf. If we use the same joist, total deflection will be 1.50 (1.25 + 0.25). However, the limit on total deflection is Span / 720, resulting in the need for total deflection to be only 0.50 (half of the 1.00 value for Span / 360). Therefore, moment of inertia for the joist must be 3 times greater (1.50 / 0.50) than moment of inertia required to support wood flooring. Using the Marble Institute standard to govern design, there will be a major design deficiency (for stone tile flooring) if the architect designed for wood flooring using the maximum deflection limit per the building code.