Installing a slate floor over existing vinyl floor?
June 24, 2009
Hello-
I plan on installing slate tile flooring in my kitchen and I have a few questions before I start. First, I have unsightly and stubborn non-cushioned vinyl flooring on top of two layers of plywood subfloor. I've decided to place cement backer on top of the vinyl floor–which is permissible according to the manufacturer's instructions, and will save me hours of labor and frustration–but I was not sure if a particular type of thinset is required for adhering backerboard to vinyl? Also, there are a few areas of the floor that are unlevel–at the door thresholds to the attached garage, which requires a step down, the sub floor dips–that may require self-leveling compound. I've read other posts about SLC on this thread, but can I apply the SLC directly to the vinyl? Or, can I just add extra thinset to this area to smooth it out?
Thanks so much for any guidance you may have!
-Marshall
Yes, I am sure it is not luan. In fact, it may not even be plywood. It looks as though it is cut in 1 by 4 planks, placed on top of plywood. The top planks look like pine. The home was built in the 1950s and by the looks of it, this looks original to the home.
Posted in Slate Floor Tile
content rss
June 24th, 2009 at 1:05 am
The backerboard must be nailed/screwed down in addition to the use of a little thinset beneath it. This means that you cannot have a thick layer of self-leveler beneath the cement board since you will not be able to nail through it. You can use self-leveler on top of the backerboard (Mapei Novoplan 2 or 6 is great). It is sometimes easier to use a layer of thin plywood beneath the backer if the low spots are severe. Then apply a liberal amount of thinset to these areas as you install the backerboard.
The purpose of the thinset is mainly to stabilize the backerboard by filling any voids beneath it, and not to hold it down, as many believe. I use 1 1/4" galvanized roofing nails to fasten backerboard but screws are ok too.
Leaving the old vinyl will cause no problems whatsoever so don't worry about that. Any good thinset will work well (Mapei Ultraflex 2, Laticrete Gold or Platinum) . I usually use a 1/4" x 1/4" trowel for spreading beneath the backerboard and a 1/4" x 5/16" or 3/8" for slate tile because of its irregular surface.
If you have questions about any details or installation, feel free to email.
June 24th, 2009 at 1:05 am
First, start with the leveling of the existing floors. Although backer board is rigid, it will follow drops and dips eventually. I would use dry mix type floor leveling compound. It probably won't adhere to the linoleum to the greatest extent, but it is easiest to apply in my opinion, You can even build it up just a touch to allow for later settling.
I would use PL200 or PL 400 to adhere the backer board to the linoleum after scratching the original up with very rough sandpaper or whatever, as much as possible to get rid of slick spots, wax, and to make better adhesion. vacuum aftger all sanding. Finally, backerboard is smooth on the upper side and has quite a bit of rough exterior on the reverse, down, side. That helps adhesion. If you set the slate right, with the correct trowel size, you should be okay after that. I doubt the slate will break on you. Grout can always be dug out and replaced easily if you start to see cracks developing in between the slate, unless you are going edge to edge.
June 24th, 2009 at 1:05 am
Are you sure its just over plywood and not luan? If there is luan underneath, it could eventually delaminate and cause the floor to fail. Otherwise, you're fine going over vinyl, just use a belt sander to rough it up. Also, if youre going to self level, do it over the backerboard, just make sure to use a latex primer so the SLC adheres to the backerboard.
June 24th, 2009 at 1:05 am
Remove the vinyl. Slate makes a beautiful floor, but if you try to save a day or two's work now, you'll regret it later when problems start to surface.