WHat happens when you lay ceramic tile directly over osb or plywood? My main interest in in the osb

Hi Brewer

OSB makes a terrible surface for any kind of tile installation and although regular exterior grade plywood is a better surface ... it's still not the preferred product for the job. OSB is compromised by the moisture in the mortar causing the OSB to swell and give a poor bond. All wood has characteristics which cause it to expand and contract making your tile installation suffer with cracked grout and/or loose tiles.

If you have the required joist spacing and acceptable substrate then either a cement board or isolation membrane such as Ditra will give you the surface required for the best installation.

Hello brewer,

I have a family room with OSB and I installed hardibacker before installing my tiles. You can see some pics of my room in Larry's Gallery. Take Harry's advice and you'll be glad you did.