ggpk Tile Floors July 11th, 2018 - 18:56:14
How thick is the subfloor and what is it made of? In new construction. ¾ inch plywood or Oriented Strand Board is a standard subfloor over joists that are 16 inches on center apart. We find that is almost never enough to meet the deflection standards in most homes. Other times there is old plank flooring beneath a layer of plywood. This is a wild card. since the engineering tables usually don`t include the value for planks in their calculation. but common sense says it does add some stiffness.
What condition does the wood appear to be in? Even if the amount of wood support seems adequate according to the tables. if it appears to have been water damaged. if sections of it look moldy or corroded due to rot or decay. it`s not doing its job. Options include replacing or reinforcing it. but not just ignoring it. Also. has it been cut into in various spots. such as a plumber cutting sections of the joists for positioning pipes? All of these problems can make the wood less effective.
It is remarkably durable. Have you ever considered that the Romans used tile that`s still around today? It holds up exceptionally well even in the highest-traffic areas. From porticos to palaces. the durability of tile has been tested and proven through centuries. So it is a long-lasting investment. A major home improvement website actually declares ceramic tile will last "a lifetime"; in other words. as long as the house is in use! Dime for dime. tile is clearly one of the most cost effective flooring surfaces you can choose.
There are formulas used in the industry to determine if the subfloor has excessive `deflection` [bounciness. lack of rigidity]. The most cited one is the Tile Council of North America standard for deflection. which is stated as L/360 as a minimum. before tile underlayment is installed. L/360 means that the floor should not bend under weight more than the length (expressed in inches) of the unsupported span divided by 360. For example. if the span between supports runs for 20 feet then the deflection should not be more than 2/3" between the center and the end. L=20 x 12" = 240". L/360 = 240"/360 or 2/3". So 2/3" is the maximum amount of movement the center of the span should be allowed to move.