Gmoore:
On all new construction I specify only 1" decking with tongue and groove edges. If you really need the space and considering the low quality of plywood being produced, the least I would advise is 3/4 inch. My experience has been that 5/8 flexes too much for ceramic tile. With any plywood, be sure to run the grain perpendicular to the joists. Apply a bead of "liquid nail" to the top of each joist just before laying the decking and fasten with screws or ring shank nails.
As a note of interest, many of the recomended plywood thicknesses were established using full dimension products. This means that 5/8 inch plywood recommended was actually 5/8 inch thick. Although full dimension plywood is still available by special order, most lumber yards now stock only "nominal dimension" or "span rated" products which are never the full thickness alluded to. A sheet of plywood sold as 5/8 inch is usually labelled as 19/32 and actually will measure at 9/16 or less. This is a 10% reduction in thickness and about a 20% increase in deflection (flexing under load). I have bought 3/4 inch plywood that actally measured to be 5/8 inch.
Once the decking has been replaced you can install the cement backer board as Tileguybob described.
Regards |
Member Since
06/24/2004
Total Contributions
214 Posts
|
Moderated by Handyman 
