Tile industry associations recommend special total load deflection limits the following tables list the components and weights of typical floor systems along with the deflection limits that apply.
Live and total load deflection for title floor.
Allowable deflection for this floor joist is approxi mately 1 2 in.
Figure 2 live loads and deflection limits are set by code.
Living room floors l 360 40 psf.
This sets an allowable first floor live load of 40 psf a dead load of 10 psf and a deflection of l 360.
3 8 2 cast in place concrete floors.
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.
Camber is a curvature in the opposite direction of the dead load deflection curve.
When the dead load is applied to a cambered beam the curvature is removed and beam becomes level.
Step 2 span table.
The dead load deflection is usually compensated by cambering.
These tables are from the icc international residential code.
Typical deflection limits referenced in code books are l 360 l 240 or l 180.
Now consider the same floor joist supporting stone tile flooring such that floor dead load is now 20 psf.
Design substrate for total load deflection not exceeding l 360 as measured between control or expansion joints.
Select the appropriate table in span tables for joists and rafters.
The subfloor areas over which stone tile is to be applied must be designed to have a deflection not exceeding l 720 of the span.
Chapter 3 of the international residential code irc provides the maximum allowable deflection for a given structural member floor roof wall etc.
Calculating dead loads the prescriptive tables of the irc detailing continu.
Therefore the live load deflection is of concern in the completed structure.
If we use the same joist total deflection will be 1 50 1 25 0 25.
The amount of flex depends on the magnitude of the load applied span of the member and stiffness of the member.
Span rafter with a 4 12 slope and no ceiling attached has an allowable deflection of l 180 which is twice the deflection allowed for floor joists.
Bedrooms and habitable attic floors l 360 30 psf.
With an evenly distributed live load of 30 psf which the tables show the floor is able to support the total weight on the floor would be about 3 360 pounds.
The table of contents indicates.
Examples of code prescribed deflection limits and live load values are.
Typically for better performing floors minimal defection is desired.
