Floor Vibration Frequency

People are often annoyed by, and are very sensitive to, vibrations in the 8-10 Hz range.
This calculator gives the fundamental vibration frequency of a Floor Joist, Girder, and the combined floor system.
For best results the frequency should be 15 Hz or higher.
For most light frame construction 7 psf would be a reasonable dead load figure. In general the floors with trouble are usually longer spans designed with 30 psf loading.
A good example to try. A floor was designed using 30 psf live load, L/360 deflection. The joist were #2 SYP 2x10's (enter 1.5 x 9.25) allowable span is 19' (enter 228") when framed 12" on center. Modulus of Elasticity is 1.4 million psi. Use 7 psf for the actual dead load, on the 19' span at 12" oc that gives a dead load of 133 lbs. The result is a floor joist with a frequency of 9.1 Hz. The girder is checked the same way. The frequency of each is entered into the third calculator to give the overall floor vibration frequency. Generally designing for 50 lb total floor load with L/480 joists and L/600 girders will give good results.

Dead Load on Joist(pounds)
Span of Joist (inches)
Width of Joist
Depth of Joist
Modulus of Elasticity (million PSI)
Frequency (Hz)

Dead Load on Girder(pounds)
Span of Girder (inches)
Width of Girder
Depth of Girder
Modulus of Elasticity (million PSI)
Frequency (Hz)
Joist Frequency(Hz)
Girder Frequency (Hz)
Frequency (Hz)