How To Reduce Floor Deflection

Even structurally sound code compliant new floors can deflect or flex more than feels comfortable.

How to reduce floor deflection.

However continuous beams result in conditions that must be carefully evaluated. You can shore up floor joists and reduce the bounce in a number of ways but. Got bounce appeared in the august 2012 issue of prosales and dealt with mitigating floor deflection in new home construction. Note it gives the allowable deflection based on a fractional span quantity so a larger denominator will yield less deflection.

See the table below. Even after fixing most of the floor s deflection issues the correct underlayment and installation method is necessary to reduce the risk of cracking in the grout joints. Frequently there is misunderstanding regarding deflection between joists. 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.

Too much bounce though can make the china cabinet wobble. For new home builders a squeaky or bouncy floor is a sign of substandard or code minimum construction practices the effect of which can erode their reputation for delivering comfortable quality. Tom s house was built in 1765 but bouncy floors aren t just an old house problem. Of course new homes also can have bouncy floors if the joists are approaching the maximum spanning distance for the weight they are supporting.

Reducing deflection according to tcna there are several factors that affect deflection including condition of the subfloor and joists joist size type and spacing and how the subfloor was fastened. For example the allowable deflection of a 12ft span floor joist with plaster l 360 is 0 4 12ft divided by 360. This is the second of two articles on proper floor framing. For beam elements such as floor joists one relatively simple way to reduce deflection is to use continuous elements that span over one or more interior supports in addition to the usual support at or near each end.

There are a variety of ways to stiffen a floor. It s a more expensive panel but if you can reduce the number of joists with wider spacing per the span tables you might balance the installed cost of that system. The l 360 standard means that the floor should not deflect more than the span divided by 360. The method or methods tom chooses depend as much on practicality as on effectiveness.

If that same joist had gypsum ceiling l 240 the allowable deflection is 0 6. A 7 8 inch or 1 1 8 inch deck goes a long way to reduce deflection in a code minimum floor says weyerhaeuser s lewis.