How is L 360 deflection calculated?

For example, the allowable deflection of a 12ft span floor joist with plaster (L/360) is 0.4″ (12ft divided by 360). If that same joist had gypsum ceiling (L/240), the allowable deflection is 0.6″.

How do you calculate floor deflection?

Divide the total span of the floor joists (in inches) by 360 to determine the maximum amount the floor can give in the middle under a live load of 40 lb./sq. ft., plus any long-term deflection due to the weight of the floor. For example, the maximum deflection for a joist span of 15′ is [15 * 12] / 360 = 1/2″.

What is l360?

L/360 is the length of the unsupported span in inches divided by 360, so for a 10 foot span, L= (10feet x 12inches per foot) so L is 120, 120/360 is 1/3 so the max deflection is 1/3″ for that span.

What is the deflection of ratio?

The deflection ratio is then: . 5 inches/360 inches or just . 5/360. If the deflection was, say 1.25 inches, then the deflection ratio would be 1.25/360.

What is excessive deflection?

Causes of Excessive Deflections in Beam Material used in the Beam. Ignorance in design of beam when we select small depth for beam but in most cases lead to excessive deflection. Decrease in thickness of the beam. It happens when we provide no reinforcement in Tension Zone of the beam.

What is deflection limit?

Maximum deflection limits are set by building codes. They are expressed as a fraction; clear span in inches (L) over a given number. For example: a floor joist appropriately selected to span 10 feet with an L/360 limit will deflect no more than 120″/360 = 1/3 inches under maximum design loads.

What’s the maximum deflection distance for l / 480?

For L/480 deflection, the maximum span drops to 15 feet, 6 inches. Those maximum distances vary based on joist strength, depth, and on-center spacing.

What does L / 360 deflection mean in wood beams?

When I am looking at the criteria for engineered wood beams these different ratings are used (L/360, L/480, etc). I have searched the web to find a definition so that can get some idea of what these beam tables are telling me. Anyone out there know?

How can I determine the maximum beam deflection?

This beam deflection calculator will help you determine the maximum beam deflection of simply-supported beams, and cantilever beams carrying simple load configurations. You can choose from a selection of load types that can act on any length of beam you want.

How much deflection do you need between joists?

Deflection. The L/360 standard means that the floor should not deflect more than the “span” divided by 360. If the span of the joists is 10 feet (between supports), then the deflection should not be more than 1/3″ between the center and the end. Frequently, there is misunderstanding regarding deflection between joists.