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Flooring and Carpeting/Porcelain floor tile on subfloor


I am planning to replace wood floor with porcelain floor tiles in kitchen and foyer area. I found there are 2 layers of polywood subfloor in these area. I wonder if the tiles can be install directly on the top subfloor. This is simple solution I can DIY. I believe there should be some reason to have 2 subfloors. There will be height problem to add another layer of cement board since the floor level is already higher than other rooms. The house is more than 40 years old. Will there any problem with my plan?


Sorry I am tardy with my reply busy at work lately.

Thank you for your question...

    If the top layer of plywood is genuine and you have "two" layers of it, then you have a very special sub-floor indeed. What you have is "old school" sub assembly that drastically reduces the amount of deflection or movement in the floor. When you add wood to this you make the floor even more rigid and less prone to flex. Once you remove the hardwood layer you will need of course to check/test the remaining layers of sub-floor to be certain that it is adequately secured to the floor joists below. So this will entail looking for nail heads and their frequency at both the side and butt seams and also within the field of the plywood sheet itself. You will want to have a nail (or add a screw) so that there is one or the other every 4-6" apart at the seams and 8-10" in the field of the plywood. Once you have reached the desired amount of anchors holding things down you may need to sand the surface of the plywood to make sure there are no chips or places where the old nails that once held the hardwood is gone and things are nice and flat. I would damp mop/sponge rinse the entire floor prior to starting and the last piece of this equation is be "sure" to purchase a thinset that is approved for installation over plywood. There is a difference and you do not want this new install coming up in less than 6 months...ok? There are numerous suppliers out there that can provide you with what you need. I see nothing wrong with your plan so get started and thanks for stopping in, feel free to return anytime...

Perry V.

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Perry Vellenga


Ceramic Tile/Marble. I can answer questions about floor preparation, tile selection, layout questions, performance of products, expectations of finish, compatabilities, questions about grout and epoxies, evaluating an installer, asking the right questions to check competence...more? 33 years this August 2012/ many years in commercial application from exterior finishes to Mall store fronts/ interior finishes like floor packages in stores inside Malls examples: The Limited, Lerner/NY, Lane Bryants, Bombay Co., Now involved in Residential new construction covering all types of interior finishes and designs.


I worked in an exclusive field of floorcovering called "Tenant Development" which is by invitational bid only, by way of a National bid list. These are large floor packages usually over 3500 sq. ft. of 18" x 18" Marble and Granite and many other types of Marble and sizes. They are specialty stores where the floor package can cost upwards of $50,000 for one store. I have also done "Structure" stores and J. Riggins stores, Lane Bryant,Express and Body Shop stores where wood flooring is used. Presently work for a National Flooring Company in the Residential new construction arena that covers most interior design elements..Granite Slab tops/wood flooring both job finished and prefinished ect..

My response's are published all across the Internet and picked up by multiple Interior Design sites and Industry related web sites where people have questions...

too many most of which don't count...

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