How much thinset under backerboard

I would use the cement special screws to attach the hardi to the plywood. Thanks Ron. The other thing is that a little mortar underneath may make the heights work out perfectly. Please explain WHY is thinset necessary? Why are screws alone not adequate? What is it about backer board that necessitates thinset as an additional agent in its installation? I am not asking to be a jerk, it just does not make sense to me. Seven years ago I did a large format tile project sq ft using screws only, as of today it still going strong, no cracks, no anything?

What benefit or capability does thinset add that without it the installation is compromised? It takes away movement. Screws or nails hold the backer down and thinset holds it up.

Once dry, it takes away any gaps and any further movement in the backer board. I do not trust any that the thinset will hold the boards down long term. I am tiling over existing tile, using mapei eco prom grip. Should I use self leveling cement instead. If so, which brand do you recommend? Foam board panels, like Wedi board or GoBoard, come in a variety of sizes and have a procedure for installing over cement.

Additionally, self-leveling underlayment works fine and would give a flat floor, if done correctly. The easiest solution, as long as the heights will match up, would be to use an uncoupling membrane like Ditra or Ditra XL. My kitchen tiles became loose one by one. I lift the wonder-board and I see a straight crack. What could be the reason? So, that tells me that there is no mortar underneath the cement board which could be the cause of your loose tile issue. If you want to use tap cons and install them per the fastener schedule then maybe that will work.

Great forum thanks a lot. I am getting ready to install tile in a small upstairs bathroom. I first poured self leveling concrete to make up for a substantial slope, I then cut Hardi backer which I will install with thin set underneath and finally screw down the Hardi backer through the self leveling concrete and into the plywood sub floor.

Does this seem like an ok idea or do I need to scrap the Hardi backer for a different product over the floor leveler? Thanks a lot, Jon. First thing, is I would check if you installed the correct leveler.

There are only certain levelers that are approved for going over wood substrates and one of those types would need to be installed.

Alternatively, some levelers require metal lath to be installed over a wood subfloor prior to installing the leveler. If you wanted to install cement board then that should have been installed first thing and directly over the wood subfloor. I am in the process of installing a new ceramic tile floor over hydronic viega radiant heat. I will use the viega climate panel, which the pex tubing snaps into. The viega installation instructions say to glue and screw the backer hardie board down.

Your suggestion is to use thinset and screws. What method should be used and if it is glue, what type? Or if thinset, what type issued over the pex tubing? Thanks for any information. Can you put thinset mortar on OSB subfloor? This is not advantech OSB just the Lowes cheap stuff. It depends on what you are installing. If you are installing cement board or an uncoupling membrane then, yes, you would thinset those down and sometimes to OSB.

What is it that you want to stick to the OSB with the thinset? Appreciate this page. I have 1 inch thick by 4 inch wide pine boards, with no subfloor underneath. The boards fasten right to the beams underneath, thus removing them is not really an option I believe. They are solid as only about 10 years old, but not tongue and groove so not super tight in all spots. I have a feeling I need to use plywood above before I put down thinset and backer board but want to confirm that.

I understand that the backer board does not add structural strength, but do I really need that if the floor itself is strong? My home has OSB as a subfloor like alot of homes now. Is it safe to say that I can treat it like a plywood subfloor and place mortar, cement board, mortar then tile or is it not even worth doing with having OSB? At least not yet. The other advantage of this is that it keeps the overall height of the floor down.

Cement board is a great way of going over OSB and the way that you outlined should work perfectly. Additionally, it helps if you can scrape, or sand, the surface to promote adhesion. If anything happens then the particle board will swell and ruin the tile. You can rent a toe kick saw if you need to get under the cabinets.

Link to instagram video about removing vinyl subfloor. You can also install backer board, like you mentioned, but then the floor height is going to be a lot higher than it currently is and you could have issues with door heights, etc. Thank you for a great forum. I am replacing 20 year old 8X8 ceramic tiles in our 80 sqft kitchen installed on gypsum. When I removed the old tiles and gypsum, OSB board revealed random spots of dried mold especially under the refrigerator.

Apparently the refrigerator had small leaks over the years but the compressor heat evaporated the water while causing minor mold therefore we did not have any extensive smell of the mold. Since I had a hip fracture 2 years ago, doing floor work was extremely difficult and expensive especially thin-setting multiple times between layers of the underlayments. I experimented laying DITRA first under the sink cabinet 4 sqft area and realized that 80 sqft will be a huge pain.

However, my enthusiasm has been curbed when I read Hardibacker installation instructions and your recommendations that I still need to have thinset under the cement board. That means I am back to where I am with thinset mess and pain and more expense. Second question is, Hardibacker is not waterproof unless I use Hardibacker Hydrodefense for Walls. Can I use Hardibacker Hydrodefense for floors? For me waterproofing and protecting 20 year old OSB from mold is more important.

Really appreciate your advice. It sounds like you need to come up 1 inch with the underlayment. I think the best way to go would be to add plywood over the floor as it is right now. You would have to check with the manufacturer to see if mortar underneath Hardibacker is necessary. I know Hardibacker wants mortar underneath but they are also assuming that you will be installing tile with a mortar adhesive.

You can waterproof over the Hardibacker on a floor if you want. Also, on one side of the tub against the wall they installed green board. At the back of the tub there is the Hardibacker where it joins into the open shower.

I had thought to put Redguard over that section which will not receive a lot of water. Am I cool? Or should I demand it be cut to the height of the tile installation and hardibacker installed.

The shower is separate from the tub. Either thickness of Hardibacker works just fine over a floor. IUsing thinset under cement board depends on your subfloor. Over plywood I agree.. They spray a wax waterproofing on the floor. Thinset will not bond to it. Most new houses have advantic in them. You have to sand the whole floor down.. It usually dry before that and you can tell by the color change of the mortar. We put the cement board smooth side out, because for reason reason I had it in my head that thin-set was a mastic and not mortar.

Am I doomed if I use thin-set on the smooth side? I have a laundry room that had a laminate sheet flooring in it. I removed the laminate to find they had put down 3 layers of it glued in various places. It all looks to be the same so I guess it was done at the same time. I finally got this up and find the glue is not coming up. Can I use a cement board to give me a clean level surface to lay my tile on?

However, if you have a wood subfloor then you may not be down as far as you need to be. Typically, the flooring is over an underlayment that is on top of the subfloor. That underlayment should come out as well. It is on a concrete floor. As I said I am down to just the remaining glue. It is hard and not coming up. I talked with a contractor and he said we could do the backer board or a leveling compound. Not sure what to do as I now have a cement floor with the glue remanence on it.

You could use a foam board like Wedi or a leveling compound. The best way to get rid of the glue is to grind it off with an electric grinder and a diamond cup wheel. Remember you are in this business for the long haul. Try to be patient and learn or to voice your concerns early, your timing can realy affect your overall experience.

I am not saying be a sucker but be a good manager, learn to have emotional intelligence and use it in your favor. Yes, if you want something specific then you do have to learn how to make sure the conditions you want are in the contract and specified.

This is all part of learning. Most of go through this learning curve. You do not have to pull out your hair, stomp your feet, or scream, simply discuss things with your contractor and if they feel they can guarantee their work they should have no problem assuring you that if you have quality problems with their work that they are willing to stand behind it and will take care of anything for you should the need arise.

I mean this is already a legal requirement for them but it helps if you can get them to reassure you and perhaps just bringing things to their attention will promt them to do better job if they are not doing it already.

Most contractors want to earn your trust and get your repeat business. This is also a part of putting together the best team you can to work with and that includes selecting the contractors you want to keep working with. Guess who I kept on my long term team? I personally never use twinset under cement board, but my cousin swears by it. At this point I would accept it, but if this is what you want I would make sure to specify specifically in the future, and have wording saying that no payment unless its done that way.

As a side note my cousin charges a upgraded charge to put it down with the thin set, so most likely you would have had to pay more to have it done that way.

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Real Estate Books. Featured Book. Get the Magazine. Search Nova. Log In Sign up. Forums Arrow Contractors Arrow No thinset under cement board. Create post. Our agreement was to put down cement board and tile. Should I have been more specific in work instructions? Should I demand he redo the job to what I think is the right way?

Should I meet him in the middle and pay a bit more? Most of the sq ft of tile is already down. What would you do? Rotate Log in or sign up to reply. I've never used thinset under cement board, for what it's worth.

The manufacturers all require it. I'll probably not make a big deal of this. I did not use to put thin set on before I knew about it and haven't had a call back. Many years of experience. As with all of these, when you read the fine print, all leveling should be done prior to their installation that includes cbus and membranes. All times are GMT The time now is PM. Thinset under backerboard?

User Name. Remember Me? Mark Forums Read. Tile Calculator. Thread Tools. Find More Posts by Buck Find More Posts by Kman. Find More Posts by Zoltan. Posts: Find More Posts by Swedes Tile. Find More Posts by cx.

Find More Posts by Dave Taylor. Find More Posts by jadnashua. Quote: Originally Posted by Buck What I am interested in is laying a sound floor but not creating a headache for someone else down the road if I can avoid it. Find More Posts by evan Posting Rules. Similar Threads. Thinset under backerboard. Thinset under Backerboard. Thinset before backerboard? A very sturdy and strong substrate. I started by placing 30 roofing paper to act as bond break to avoid squeaks before installing the cement board being sure to stagger joints.

Is thinset truly necessary? I have two questions for you. We are in the process of gathering supplies for a basement bathroom redo. The walls are currently papered. What we want to do is tile everywhere!

Floors, walls and ceiling within the shower. My question is do we need to put up backer board onto the walls that are block? I know we need to do inside the shower regardless of wall construction, but, in the rest of the bathroom can we just put the tile directly on the block walls? Or will it be too hard to get a level job done due to the strike lines? Would it be best to use backer board everywhere? Also, how do we attach the backer board to block walls?

Screws and thinset?