Tile Over Osb With Silent Floor Joists

Floor joists beneath ceramic tile floors must not deflect more than 1 360 of their span.

Tile over osb with silent floor joists. For a given floor joist as you increase the distance between supports the joist will deflect a greater amount. 1 2 cement board over 5 8 plywood is often frowned upon as the cement board offers up no rigidity to the floor assembly. Floor joists are basically wood i beams. I have ripped up many a floor with 1 2 plywood as the tile substrate over 5 8 sheathing.

As the plywood or osb expands the ceramic won t. Tile can be installed directly over existing tile given that it is free of cracks and there are no loose tiles. Jim and rich advise using a bond promoting primer to enable the mortar to better adhere to the existing floor and to set the floor with a specialty polymer modified mortar. Tile over tile or resilient flooring.

This bounce will crack the tiles. Uncoupling membranes aren t recommended for tiles smaller than 2 inches square and should not be used when covering old hardwood flooring due to adhesion problems. Plywood and osb expand and contract with humidity and temperature much more than ceramic tile. Assuming your joists are 1 grade and the span is no greater than 16.

Regular seasonal humidity shifts are significant enough to make the average 10 x 10 wood subfloor floor expand or contract as much as 1 2. To remedy this situation cut a piece of joist material 2 8 2 10 or 2 12 depending on the circumstances to fit crosswise between the two joists under the soft flooring. Building codes specify the minimum joist depth and spacing typically 12 or 16 inches on center for spans up to 20 feet but those requirements are intended to prevent plaster ceilings from cracking not to. Always follow the manufacturer s installation.

Ceramic tile doesn t expand contract nearly as much. Osb panels provide an excellent base for many types of finished flooring including ceramic tiles if careful attention to the construction and preparation of the subfloor is paid in order to avoid costly callbacks. This house was built 7 years ago and since i selected a vinyl floor the builder placed my joist 24 inches on center. Planning and patience along with these tips will help ensure that you install the quality of finished flooring you are looking for.

The builder has recommended hardwood over tile for the job but thought a 3 8 or inch piece of plywood with ditra on top would also suffice. A 3 4 inch plywood subfloor on a joist structure with 24 inch spacing needs the extra thickness of cementboard or the floor will flex and the tiles will crack.