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″.

How is L 360 deflection calculated?

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.

How do you calculate joist deflection?

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″.

Which is better L 360 or L 480?

I prefer to go with a span chart that uses L/480 for the live load. That means L/360 is implied for the total load deflection, and it will result in much better floor performance. With roof trusses, the typical deflection limit is L/240 for live load, and L/180 for total load. They can have a lot of deflection.

Is my subfloor strong enough for tile?

How Thick Does the Subfloor Need To Be for Tile? Tile is heavy, and the larger the floor you’re tiling and the thicker the tile, the heavier it’s going to be. That’s why, on average, your subfloor should be at least 1 ⅛” (2.86 cm) thick with a layer of concrete or ¾”-⅝” (1.91 to 1.59 cm) plywood or OSB underneath.

What is the best floor deflection?

Some experts say the deflection should be no more than L/360 for floor spans up to 15 ft. and no more than L/480 for greater spans.

How thick should a plywood subfloor be for tile?

1 1/8″
The subfloor under the tile should be at least 1 1/8″ thick, with a minimum of 5/8″ thick exterior grade plywood topped by 1/2″ cement backer board.

Can tile be too heavy for a floor?

No, tiles are not too heavy for a second floor because tiles are generally a lightweight material distributed over an even load. Architects and civil engineers ensure that a structure is capable of handling a reasonable amount of additional load.

What is the L 360 standard for floor deflection?

How do you calculate floor deflection in construction?

Keeping this in view, how do you calculate floor deflection? Calculating 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.

What is the maximum deflection allowed on a ceiling?

A general rule for limiting deflection of simple spans, is that the deflection should not exceed the span (in inches) divided by 360 (max D= L/360). The deflection for exposed ceiling beams at the roof is often allowed to be 50% to 100% greater (l/240 or l/180).

How much deflection should there be between floor joists?

Deflection. 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. For example, while joist manufacturers regularly meet the standard L/360 criteria for code construction with 24″ o.c.