I need to replace the [galley] kitchen floor in my 1953 raised floor home in Southern California. I have 1 3/8″ between the floor joists and the existing floor and door sill and I want/need the floor to match their height.
Can I effectively install a tile floor with the 1 3/8″ thickness limit for subfloor, hardibacker, thinset, and tile? Perhaps 3/4″ ply, 1/4″ hardibacker, and tile? If not, do you have any flooring recommendations other than sheet vinyl or more of the red oak strip flooring that is in the adjacent room?
I’m open to strengthening the underlying joists as much as possible, if necessary.
Thank you for any advice you can offer.
Steve
Replies
Yes you can, and still keep your warranty. I whole heartedly advise the use of Hardibacker. it's compresive strength is around 7000 psi where all cement products are around 2000-2500 psi. It's autoclaved, the others are air dryed, and it is the ONLY one I know of that allows the use of O.S.B. as a subfloor(the TCA tile Council of America does not recognize O.S.B. as a suitable subfloor. 1/4" is fine as long as you put down mortar first and tape your joints with alkali resistant tape.
Thank you for the advice - it is appreciated. I have no intention of using OSB as the subfloor, but it's nice to know that I could with Hardibacker. I wonder if the use of mortar would increase the thickness of the floor beyond 1 3/8" for plywood, HArdibacker, mortar and tile.Another question that I thought I knew the answer to but now have some doubts: Would it be better to go with a thinner ply subfloor and thicker Hardibacker [5/8" ply w/ 3/8 Hardi?] or thicker ply and thinner Hardibacker? Thanks,
Steve
Steve,The thicker ply and thin Hardibacker is best. The Hardibacker adds no appreciable stiffness; the plywood does.Bill
That's what I originally assumed; thanks for reassuring me.Steve
I think the mud will push you past that 1 3/8", how important is that height? You could consider adding joists @ 8" oc allowing for thinner ply.Or if your existing joists are very firm, skip the backer board and just go w/ real plywood no OSB.
Thanks. If push comes to shove I can and will add joists as the 1 3/8" height is necessary if the kitchen floor is to remain even with the surrounding, adjacent flooring. Is a particular type of ply subfloor better than others. I have plenty of Baltic Birch ply lying around, but I don't believe it is rated for subfloor application.Steve
The mortar really doesn't add much height. a 1/16" or more. You comb it out at a 3/16" or less but then you smear the mortar down to the 1/16".
As to the second question, I don't really know which is better, but traditionally everyone uses 3/4" ply and then 1/4" Hardi (they don't make a 3/8") but if in doubt I would use 1/2" wherever possible. I preach about making a floor 1 1/2" finished thickness. (3/4 ply plus 3/4 wood = 1 1/2) 3/4 ply plus 1/2 c.b.b. plus 1/4 tile =1 1/2".
Steve
We install cementitious overlay systems (San Diego), and have worked with plenty of situations like yours. Use a minimum of 3/4" t&g, glued and screwed. If you want a cementitious floor, (stamped concrete, chemical stain, etc) you can staple down 2.5 lb expanded metal lath and fill it with a polymer concrete mortar bed, top it with your desired finish. This is a very simplified answer, but I can help you with specifics if you desire. Yes, it works. I did my home office floor last month with 5/8 t&g glued and stapled over the existing 40 year old, badly installed 3/4 ply. 1/4" stamped polymer concrete overlay over the mesh and mud, topped with a coat of self leveling epoxy and finished with an acrylic urethane. The stamped overlay is not something you want to tackle yourself without experienced help, but you could do all the rest yourself.
Kaz
Thanks for all the help. It's been a long time since I've worked with any sort of flooring other than hardwood. I'll rip out the existing floor tomorrow, screw and glue 3/4 T&G ply and add 1/4 Hardibacker and 1/4 tile. I may also shore up the joists underneath while I have the floor open if I find any damage or weakness my initial under the house inspection missed. Thanks again.And now for the hard part - finding tile that my wife and I both like.Steve