Expert: Bruce E. Johnson - 10/10/2009

Question
I am remodeling bathrooms for the federal government and have ran into a problem. the existing walls are wire pencil studs with 3/8 buttonboard and 3/4" plaster.  Can I tile over this or do I have to put up cement backer board?  There is nothing to nail to because of the type of existing stud.  If I have to tear down the wall and reframe it, my budget will be blown out of the water.

Thank you in advance,

Bob

Answer
Hi Robert, most certainly you can tile directly to this type of wall system..as long as the paint is in decent condition.  The plaster is more than substantial but if there are thirty coats of paint on top of the plaster it may create a poor substrate.  I would definitely use a thin set mortar as opposed to a mastic for the install.  I just completed a project with similar framing.  If  you have to screw on a backer board you can locate the cold rolled "pencil studs" and screw to them using a self tapping screw.  I would try the thinset over the existing substrate first.  Follow the thin set instructions regarding a painted surface. You may be required to rough up the surface first to facilitate adhesion.  I hope this information helps, please feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com