Subfloor Thickness For Ceramic Tile

We are planning on using ceramic tile with granite counter tops.

Subfloor thickness for ceramic tile. 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. The subfloor is 5 8 t g. A subfloor system that worked fine for a single layer of ceramic tile may not be strong enough to handle the many hundreds of extra pounds added when a second layer is added. Typically made of plywood or osb and ranging in thickness from 19 32 to 1 1 8 thick the subfloor is truly structural second only to joists in this respect.

Subfloor holds up all of the above layers of flooring as well as everything in your house people dogs cats pianos furniture. 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. 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. This guide will show you how to prepare your subfloor for a tile installation project to ensure that it s fit to support ceramic or porcelain tile.

I have visited several tile stores and received conflicting subfloor thickness requirements. The thickness of plywood panels in a subfloor is regulated by the spacing of the joists. The subfloor must be structurally sound as well as thick and stable enough to hold the weight of the tile without moving or flexing. Most of the cabinets are on the perimeter on the room with a peninsula that runs to the center of the room 7 from the outside wall.

With ceramic tile you also need to limit the deflection between joists which is a function of the subfloor thickness and how it is installed. This number is known as a span rating. Preparing a subfloor is an essential step for installing floor tile it provides a level surface that will allow the tiles to properly stay in place. An extra layer of ceramic tile adds substantial thickness to the flooring layer.

When installing a plywood subfloor on top of the slab at grade the. It sounds like your joists are well within the acceptable limits of l 300 so your main concern is the deflection of the subfloor between joists.