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Tile Primers
Avoid Making A Costly Mistake
Or maybe you’re just here because you love reading my tiling stuff (if you are, I appreciate you <3)
Whatever the case, this buyer’s guide is here to educate you on everything you need to know about the magical world of Tile Primers and why you need them! You will also learn about the best tile primer for every substrate.
Hello and welcome to another Tilersplace article!
Today we’ll be diving into a commonly overlooked element of DIY tiling, Tile Primers! Also known as tile adhesive primers or tiling primers.
My name is Carl Anders and I’ve been doing this tiling thing as a profession for just over 25 years. I’d like to pass on my experience so that your next tiling job lasts for ever!
Tile Primers Introduction – The Downplayed King
The vital role they play in a successful tile installation is often overlooked by their simplicity to use. Just get a broom or paint roller and slap it onto your substrate. Done.
Surely, something that is so easy to apply can’t be that important right?…WRONG!
Think about the humble tub of margarine. It’s cheap, spreads on easy with a knife and it isn’t very exciting. But you wouldn’t imagine making a sandwich without it right?
Otherwise, your peaceful lunch turns into a handful, with all the tomato and meat sliding around like kiddies on a slip n’ slide. None of us need that in our lives.
So remember, just because something is insignificant or easy to use, doesn’t mean it isn’t important.
How does a tile installation fail?
The thinset that was applied to glue down the tiles, has been applied over a dirty surface and instead of adhering to the substrate, it adhered to the dust and oils sitting on top of it.
Once traffic starts walking over it, those stresses start moving the tiles and eventually they pop off the floor and get loose.
Another reason that a tile installation can fail from lack of a primer is from the thinset not curing properly.
Tile thinset is a cementitious based compound, and like any cement based product, it requires water to set properly. If there is a lack of water, then it’s full strength will never be realised and it also won’t stick properly to it’s substrate.
When a thinset is applied over an unsealed substrate like concrete or fibreboard/cement board, that substrate will suck up the water from the thinset during the curing time.
This results in lack of adhesion and strength in the thinset, this ultimately leads to a compromised tile installation that will never last as long as it should. Think one year instead of 10+ years.
I hope that know you understand why tile primers are so important and why they should always be used! With that, let’s learn more about these amazing products so that you can purchase the right one for your tiling project.
Tile Primers – What Is It?
It can be applied with a broom, paint brush or roller – depending on the type.
The primary role of a tile primer is to create better adhesion of a thinset, mud bed or self leveling underlayment (SLU) to the substrate (the surface you’ll be tiling).
A latex tile primer can also be mixed in thinset to enhance it’s bond strength, water-resistance and bond-strength. The added properties vary from product to product.
• eliminating dust and other surface containments
• stopping the substrate from absorbing all the water in thinset, self leveling underlayment’s etc (hence allowing a proper and strong cure.)
• adding grit or texture to a smooth surface to allow a strong bond.
A tile primer is also used before applying topical waterproofing compounds and helps the waterproofing to fuse effectively to the substrate.
Without a primer, a layer of waterproofing can be peeled off with your fingers once it is dry as it hasn’t adhered properly.
In essence, a primer is the first step in a tile installation.
A Tile Primer Is NOT Tile Paint
On your journey to learn more about primers, your search engine may have shown you results talking about tile paint. Please don’t get tile paint confused with tile primer as they are two completely different things.
What Is Tile Paint? Tile paint is a specialist paint that is designed to be applied directly over tiles to transform an expensive and luxury product into a flat, monotone colored surface.
Tile paint is often seen as the quickest and cheapest way of refreshing an old tile installation but it’s mostly a method of delaying the inevitable – removing the tiles properly and retiling with a new tile.
Tile paint is not hard wearing, especially on floors and will wear out unevenly, creating a undesired look that will require a reapplication of the paint.
The tile primers discussed in this article are not designed to be used before tile paint is applied.
When Can I Use A Tiling Primer?
A tile primer should be used after the substrate has been deemed ready for tiling. This is generally after you have ripped up the carpet or installed the dry wall, etc. Then once the dust and general debris of building has been cleaned up, the best tile primer for your task can be used.
You can apply a tile primer onto floors or even walls. (If they are lined with a cement sheet like Hardiebacker.) To apply tile primer to walls, a little foam roller works best as it applies a neat coating without making a mess.
A tile primer generally only needs to be applied once on the substrate if you’ll be tiling straight onto the substrate or waterproofing it.
If you will be applying a self leveling underlayment, it’s recommended to apply a coat of primer before pouring the compound and another coat of primer on top of the dried levelling underlayment before tiling or waterproofing. This is because self leveling underlayment is cementitious and can absorb water just like a substrate. This can lead to improper curing of your thinset and waterproofing.
How To Use a Tile Primer
A thick resin-based tile primer like Mapei Eco Prim will require a nap paint roller and a paint brush.
A water-like acrylic based tile primer like Custom LevelQuik® Advanced Acrylic Primer will require a soft bristle broom to apply.
No matter which tiling primer you use, the aim is the same : the achieve a uniform coat of primer on the whole entire substrate that you are wishing to tile over.
If you splash the primer onto any surface that you won’t be tiling, then wash it off immediately with clean water. Wash your tools with clean water after applying the primer to avoid the product drying onto them.
How To Prepare A surface For A Tile Primer
While every manufacturer has their own instructions on how to use their product, there are a few steps that apply to every product.
2. Thoroughly sweep up or vacuum the area you’ll be priming to ensure that the primer doesn’t stick to dust. This will affect the final result.
3. If there are patches of oil residue, paint, oil, varnishes or any finish that can stop the primer from absorbing into the substrate, be sure to remove it before. This can be done with mechanic scarring like a grinder or sandpaper.
6. Avoid pooling and any high spots.
7. Wait the specified time on the primer packaging before carrying on with the next step in your tiling project.
Tile Primer Use Cases
Tile on Tile Primer
A very popular use of a resin tiling primer is to lay tiles over the top of old tiles. This is generally done when you want to spruce up or add a modern look to a tiled room. Bathrooms are very commonly tiled over.
The tile primer will be painted over the top of the tiles and grout, and provide the thinset with a sticky and rough surface to adhere to.
Self Leveling Underlayments/Compounds
A common question I find is : Do I need primer for self leveling compound?
Yes, a primer is a requirement when using a self leveling compound or underlayment. Every system comes reccomended with a tile primer that needs to be applied to the substrate before it is poured. By using a primer, you remove any contanaments and seal off the substrate from absorbing the water inside the self leveling underlayment. This ensures a proper bond and a strong cure, ready to be tiled over.
Best Tile Primers
One tiling primer is basic acrylic based milky liquid and used on porous surfaces like concrete or fibre board. The other thicker type of primer is resin based and works on non-absorbent smooth surfaces like existing tiles.
I have selected a range of primers that should cover most of your use cases, just select the primer that sounds like it’s right for you.
Generally, the more expensive primers have better performance so if you’re not sure, just buy the expensive and thicker primer and rest assured it’ll work.
MAPEI ECO-PRIM GRIP – Overall Best Primer + Best Tile On Tile Primer
The Big-Daddy of Tile Adhesive Primers, Mapei Eco-Prime Grip is a synthetic resin-based primer that works on the most difficult of situations.
This thick boi should be your choice when failure is not an option. It can adhere to all porous and fibrous surfaces and also highly smooth surfaces like vinyl and existing tiles.
It will create a sticky and suitable surface for all tile adhesives and self leveling underlayments to adhere to after it has dried properly.
Only one coat of this primer is necessary and it can be used both indoors and outdoors.
How To Apply:
Mapei Eco Prime should be applied with a 3/8″ nap paint roller and a paint brush to achieve a uniform coat. Allow 3-5 hours to cure properly.
Coverage:
1 U.S. gal = 150 to 300 sq. ft. /3,79 L = 13,9 to 27,9 m2 (actual coverage is generally less than stated by manufacturer.)
Primer Use Cases:
This is my go-to for any challenging substrates or when tile on tile is a viable option. I use it to surface prep before pouring a self-levelling compound in heavy trafficked areas. This primer is about as good as it gets in terms of primers, it’s pricey but the peace-of-mind is well worth it.
Limitations and disadvantages:
While this is a product that promotes adhesion, it’s performance can still be effected by paint, asphalt, wax, oil, sealers, curing compounds, and poorly bonded or incompatible adhesive that is on the surface. If your substrate contains any of these things, I’d recommend sanding and roughing up the surface, otherwise the primer will simply stick to the wax or oil and not the physical substrate. It cannot be used in permanently immersed applications like swimming pools, outdoor ponds or spas.
Loose tiles or flaky adhesive should be removed as they will affect the final result.
If you are not sure if your substrate is suitable to be primed, just shoot me a comment below this article, I actively monitor comments so I should be able to help.
Buying Tip:
If you have a large job, the 3.5 Gallon bucket works out much cheaper.
Custom MBP Tile Primer
MBP Tile Primer is a more affordable tile primer with similar use cases to the Mapei Prime Eco Grip.
It is also a single part primer that can be used on smooth and porous surfaces. What makes this one different to Mapei is that it has added aggregates to produce a more gritty surface that will aid in adhesion
It is not suited for exterior commercial uses or in areas subject to heavy water saturation or immersion – keep that in mind!
How To Apply:
Apply Custom MBP with a paint brush, 1/4″ or 3/8″ nap roller.
Coverage:
1 U.S. gal = 150 to 300 sq. ft. /3,79 L = 13,9 to 27,9 m2 – The same as Mapei Eco Prim (actual coverage is generally less than stated by manufacturer.)
Primer Use Cases:
This primer is used in similar cases to the Mapei, be it adhesion to tricky smooth surfaces or even tile on tile. It has a few more limitations over the Mapei so I prefer to use it in residential homes only and in areas that won’t see excessive water like the living areas or hallways. It’s more affordable price-tag makes large jobs easier on the client’s pocket.
Limitations and disadvantages:
This primer has similar limitations as the Mapei; do not apply over paint, wax etc without removing them prior.
This is inherent with any coating. The main things to watch with this tile primer is that it can’t be subjected to heavy water saturation and it can’t be used with Saltillo tile. It also can’t be diluted and requires thorough mixing before use, so if you don’t have a drill mixer, it’s an additional tool you need to acquire.
Custom LevelQuik® Advanced Acrylic Tile Primer
This is a basic, acrylic based tile primer designed for priming concrete floors and fibresheets before tiling or applying a self leveling underlayment.
It’s a great tile adhesive primer and can be applied liberally to substrates.
Acrylic based primers are what I use on a daily for common jobs that are on concrete or fibresheets like HardieBacker. I always keep this stuff in my truck and use it on a daily. Whether I’m tiling or applying topical waterproofing, this stuff is excellent prep for that.
This sort of primer can/must be diluted with clean water as well, meaning that you get more bang for your buck and even more reason to use a tile primer!
How To Apply:
Use a soft bristle broom and sweep it onto the substrate. Any pooling of liquid should be swept to achieve a uniform coat.
If applying over cementitious surfaces, you can dilute the primer 3:1. For example 3 parts water to 1 part primer. Surfaces that are very porous should have a second coat applied once the first one has dried.
Coverage:
1 Quart (946 mL) Porous 1:3 (primer:water) 150 ft² (13.93 M²) to 300 ft² (27.89 M²)
Primer Use Cases:
This tile primer is a great every day primer for situations where you are working over porous and absorbent surfaces. Anyone tiling over a cement floor (old or new) or over a floor that has been covered with a cement/fibreboard, then this primer is more than adequate for the task.
Limitations and disadvantages:
This primer is not suitable to be used over Luan plywood, particle board, parquet, cushion or sponge-back vinyl flooring, metal, fiberglass or plastic. Wooden surfaces should be covered with a backer board first in any case, then you can prime that board with this acrylic primer.
Some metals and plastics can be tiled directly with highly specialist tile adhesives otherwise you’ll need to prime it with one of the other two primers mentioned in this review first.
Tile Primer Drying Times
It is best to obey these curing times, even if the primer seems to be ready to be worked over as the chemicals will still be reacting and achieving a full bond with the substrate. This is especially the case with the thicker primers from Mapei and Custom.
You can open up windows or setup fans in rooms with poor air flow to help with curing.
Tile Primers Conclusion – Your Key To Success
They are an investment in a property and they are also considered a luxury item. You don’t need them in a home or commercial property for that building to be functioning.
Sure, you can buy some dirt cheap tiles and slap em in your rental property because the tenants won’t wreck em as quickly as vinyl or carpet, but the tools and materials required to install those dirt cheap tiles still cost.
So when you’ll be spending all that money, you’ll want to be sure that your investment will last as long as possible and not crumble away after a year or two.
By using a tile primer during the installation phase, can insure your tile investment will last. A little extra money spent today will save you a fortune in redoing it tomorrow.
We looked at three tile primers today that will work in nearly every situation and substrate that is possible to be tiled over.
Mapei’s Eco Prim Grip was deemed to be the best tile primer overall thanks to it’s large field of capabilities and flexibility to be used across a wide range of substrates.
It is also possible to be used as a tile over tile primer, where you can install new tiles over existing tiles.
This is a popular form of renovation and helps saves time and money in demolition time and disposal of the old tile debris.
We also looked at two other tile primers which were more affordable over the Mapei and both featured their unique advantages and use cases.
Hopefully this tile primer guide convinced you to properly prepare your substrates for tiling next time you start a project and will go order your tile primer after finishing up here.
Just wondering can ecoprim be used over glass tiles?
Hi Gord, thanks for the question!
I checked the technical data sheet for you and YES you can use Ecoprim primer over glass tiles.
Hope that helps with your project.
– Carl
Very good information. I am tiling over tile in my shower (I’m thinking it’s porcelain). I used a belt sander with 36 grit on it but you can’t tell so I thought about priming it. Then I read your column on priming. Do I need to use a grinding wheel on it if I’m applying Eco primer. Thanks, David.
Hi David,
Thank you for the comment and dropping by my site.
In theory, the Eco Prim dosen’t require surface preparation but since it is a shower, I would give the existing tiles a blast with an angle grinder. A grinding wheel like this will remove a lot of the shiny surface of the tile and provide a very coarse and excellent gripping surface for the primer. It will bond immensely well if you do that. You can also use a standard stone grinding wheel if you got one, it won’t remove as much material but still buff up the surface nicely.
So, if you got the time – then definitely give it some love with the grinder and then apply the Eco Prim.
Hope that helps,
Carl.
I want to tile my kitchen backsplash. It is currently orange peel textured with a coat of semi gloss paint. Do I sand the wall a bit then put a coat of primer? Anything else I can do to increase adhesion?
Hi Rodney,
That’s correct. If you do those steps, you’ll have more than enough adhesion for your wall tiles. An extra step could be to wipe down the sanded wall with clean water and a rag to remove any paint residue from sanding. Then apply your primer. You should be good as gold to tile after that.
Have fun with your project.
Hi. We put tiles on for floors and they are popping up. Should we remove them and add the primer you recommend to do we have to remove the flooring. Thanks for your help
Hi Dave,
In what way are they popping up? Are they actually just coming off the floor or are they “tenting”? Tenting is when two tiles lift and form a sort of triangular tent shape.
If they are just coming clean off the floor then I would say there would be a few issues as to why this happened. One, yes the surface was improperly prepared and the thinset did not adhere well. A primer would have helped with this. Also, I’m thinking your thinset may have been too dry when you applied the tiles and didn’t bond properly with them. You could also have had a lack of thinset coverage on the tile itself, did you back butter the tiles before setting them?
Without seeing the job I am just throwing out everything that comes to mind, hopefully it gives you some insight. And yes, if needed, lift all the tiles that are loose or easy to lift and apply a primer. Be sure to remove any of the old thinset beforehand.
Thank you for dropping by my website, if you have further questions, please let me know.
Hi Carl: I am a novice at tiling and thought it might be a good idea to PVA over some existing quarry tiles prior to putting some new tiles down.
I have since read this is not the case – can I just now put a primer over the PVA and if so which one – if not what should I do?
Thank you.
Hi Dave, I have replied to your email but for the benefit of other readers I’ll attach an amended version here as well.
Yes, you definitely should not tile over those quarry tiles if you’ve applied a layer of PVA.
Unfortunately the whole PVA glue as a tile primer has caught a lot of well meaning people out. I’m not sure where this idea came from but PVA is not suitable as a primer for tiles for many reasons.
PVA just creates a weak layer between the substrate and the tile adhesive, it’s a glue after-all. So essentially, your whole tile installation rides on how well that PVA has stuck to the substrate = not well.
Also, PVA returns to liquid form if any water touches it, so in high traffic areas, outdoors or wet rooms, water will find a way into that PVA and cause it to be liquid. When it’s liquid, anything above that layer of PVA will become loose and fluid = your adhesive and tile. Which means tiles lifting up, grout cracking etc.
So what should you do?
If it’s possible, I’d try remove as much of the PVA from the quarry tile as possible. A wet sponge and a bucket of water should help. If it’s thick enough, you might be able to just peel it off.
Then you can apply some Mapei Eco Prim Grip over the quarry tile and that will make it ready for tiling. You can use alternative brands if Mapei isn’t available in your area. Custom MBP is another alternative.
I know all this sounds like a lot of hassle but it’ll be well worth it in the long run. Why invest so much time and effort into putting in new tile if it’ll fail in a years time (PVA primer jobs usually fail within 6 months).
Hope that helps!
Hi …can you paint over eco prime grip? shower walls are covered with light old pink ceramic tiles…I want to paint them …I was trying to sand them with 60 grade sand paper but the tiles are not fully flat…they have two different shines to them…so can they be eco grip primed then painted with acrylic tile paint?
Hi Alexa,
Eco prim grip will hold to the tiles but the paint may wash off in the shower. Check if the tile paint is rated to be used in wet areas before buying the materials. I have never worked with tile paint so unfortunately I can’t be of more help than that.
hi, what primer would i need for thistle dri coat for tiling
Hi Allan,
A standard acrylic tile primer can be used to prime over plaster.
Hi, Just wondering what to use over the sticky adhesive left on my plywood after removing vinyl flooring. I removed as much as I could , but can still feel it sticking to my shoes as I walk over it. The floor was laid 14 years ago and putting down tile now. I was told by a friend to use Mapei Primer T. Is that ok or Mapei Eco-Prime Grip? Thanks for your advice!
Hi Lou,
Mapei Primer T is a general purpose acrylic primer. If the plywood is heavily saturated with the residue, then go with Eco-Prime, but if it’s only in places and not too thick, then Primer-T should be adequate.
You can always rough up the residue with some sandpaper or a cup grinder as well to be extra safe.
Hope that helps.
Carl,
I am prepping my concrete floor laundry room for tile and the first order of business was to scrape up some tile, and two layers of old vinyl. Now I’m left with a black adhesive on the concrete. I’m thinking I could prime with the Eco Prim, feather the floor into a newly installed floor drain (with concrete?), apply some self leveling concrete to address some low spots, install decoupling membrane, and finally install my porcelain tile. Could you comment on this approach? What would you use to slope towards the drain? Do you think the Eco Prim would adhere to the old black adhesive? -Thanks!
Tyler
Hi Tyler,
Your plan sounds excellent. You can feather the slope with a mud screed as long as you have a minimal thickness of 3/4″.
I’m not too sure about that black adhesive, technically if it’s bonding well with the substrate beneath, you can roll with a primer and continue tiling. I’d try rough up the adhesive first with either sandpaper or a grinder and then prime. In any case, Eco Prim will work great on that surface.
Hope that helps.
Carl,
Thanks for the advice. I noticed that the Mapei thunder I have requires any new concrete to have a cure time of at least 28 days. Does that apply to the mud as well? Also, if the mud requires at least 3/4” thickness how can I manage to taper off to near zero by the time I get to the drain?
Sorry…thunder should be thin-set. Lol
Hi Carl,
I’m tiling a painted porch that gets some water when it rains in San Francisco but stays dry the rest of the time. I need to put some self leveler in a couple areas, was planning to use hardibacker and redgard. I see now that I probably don’t need the hardibacker but since I have it already…
So, what kind of primer goes on the painted porch first? Then I was going to use thinset with a primer to attach the hardibacker, use the self leveler for the low spots, use the primer you suggested over the hardibacker and self leveler, then redgard, modified thinset, tile. Tile is porcelain 12 x 12.
Thanks!
Hi Xan,
I would recommend you sand down the paint first and get rid of any flaking patches. You won’t need to fully remove all of the paint but roughing it up and removing any loose areas will go a long way towards getting a proper bond with your primer. I’d say you can just go with a standard primer after that. If the paint on the porch is too thick or creates problems, you can apply Eco-Prim as it’ll bond very well to it.
Good luck with your project and I hope that helps.
Question: I need to re-tile a deck that is over my kitchen. Currently the deck has tile. Can I use Mapei Eco Prim and tile over existing tile outside? The deck is exposed to outside weather such as rain and sun. I live in Southern California. What is your recommendation?
Hi Rudy,
Mapei states that Eco Prim is suitable for exterior walls and floors, so it should be fine to use over those old deck tiles. As long as their structurally sound and not loose, you shouldn’t have any issues.
When doing a shower with hardi backer, should I use a primer and if so which one before I use aguadefence?
Hi Aaron,
Yes, any type of topical waterproofing will require a primer. Otherwise it won’t achieve a proper bond with the backer board and may peel off. Primer-G from Mapei is compatible for your waterproofing and substrate.
Hi Carl,
As an extra measure, would applying the Mapei Eco Prim to the backs of Porcelain tiles (with the proper curing time) before they are laid onto the adhesive be a good idea. It just seems that with the lack of porosity or key to the back of the Porcelain tile that this can be one of the easiest places for failure of adhesion ?
Hi Matt,
Thanks for the interesting question!
You’re on the right track with prepping the rear of the tile but you want to key in the tile with your thinset, not a primer. You can either fill in the voids with the flat of your trowel or do the common method of “back-buttering” before you lay the tile. In that instance you spread out the thinset as usual but also spread it onto the back of the tile with the notched side of the trowel. This gives you 100% coverage of thinset which is essential for large format porcelain tile.
If you notice a lot of kiln dust on the back of your tile (fine white powder), you can wipe it off with a wet sponge before work as well. Doing all that will definitely give you plenty of adhesion to the tile and your substrate without any failure.
Hope that helps and thanks for adding to the conversation!
Carl, help!
I have (slightly warped)wood flooring. We’ve already sanded and applied wood filler. I’ve bought groutable(peel and stick) luxury vinyl tile thinking it would be easy :/ I primed a portion with a TEC multipurpose primer and attempted but it won’t adhear. I read your whole article and learned alot but I have lots of doubt. Any input of yours would be greatly appreciated!
Hi Maria,
Was the primer dry before you tried stick a tile down?
If it was, maybe the adhesive on the back of the vinyl tile is simply not strong enough. You can try purchase a specialist glue and use that to help glue the tiles down. You’re slightly warped floor should still allow the tiles to conform to the shape and hold. You can head to your nearest home improvement store and ask someone there for a glue that works with vinyl tile.
The glue will have instructions on how to use it, but usually it’s apply to both the surface and the tile, let it dry a little and then press it down.
Hopefully that will solve the problem! You did well by priming the surface first, that’ll kill any dust that prevents proper adhesion.
If you have any further questions, let me know!
I’m redoing my shower. Other than the curb that is under the glass block all tile has been removed and laid. The curb has tile that is very sound, I plan on taking diamond cup wheel to it, should I prime that or not? I’m using pro lite thin set for large format tiles. Curb is about 6 inches high.
Hi Daniel,
If you’re roughing up the tile with the diamond cup, it should be fine to tile over without primer. Just be sure to clean off the dust with clean water before tiling.
Hope that helps.
I am tiling a kitchen backsplash. I put a layer of drywall mud over the surface after removing the old laminate backsplash. I have Mapei Eco Prim Grip to use as a primer. It says to use a self-leveling underlayment within 24 hours of application. Does that 24-hr window also apply to vertical wall mortar? I don’t know if the wall mortar can stick to the primer after it dries. Also, is this the product that you would use for my project?
Hi Michael,
You should be fine to just use the Mapei Eco Prim and tile over it using your wall mortar. The instructions are referring to instances where you apply the primer over existing floor tiles as this primer is mainly used for that sort of thing. It’s nothing to worry about.
Since you have already purchased it then you may as well use it but it’s a little overkill for your use-case. A standard acrylic primer would have been sufficient.
Hope that helps, let me know if you have any further questions.
So the same acrylic primer that I use for painting will work?
Any acrylic tile primer like the HENRY 564 floorpro that I mentioned in the article would be my pick. I haven’t tried using a paint primer for tiles so can’t honestly say but I’d avoid it as the formulations can be different.
I have the same question as Michael regarding the 24 hour application window. I am using Mapei Primer T on new drywall for a kitchen backsplash replacement. The instructions note a 24 hour application window for drywall. Does this mean I have to apply my tile within 24 hours of Primer T application? It’s a bit confusing because it does say for flooring/underlayment but also says for drywall. Just want to clarify as we already applied the Primer T to get ahead of the game but we can’t install the tile for a few more days. Thanks so much for this great information and site, we’ve learned a lot!
Hi Sam,
You should be fine with the one coat of primer and starting tiling after a few days. Just try not to splash any cooking oil or general dirt whilst using the kitchen in the meantime. If it does get dirty, you can degrease the surface and apply another coat of primer just to be sure. Since it’s a wall and won’t be under the same stress as a floor, you won’t have any issues with adhesion.
Good luck with the project and I appreciate the comment and compliment 🙂
Hi! I want to put tile on part of my bathroom wall, outside of the shower that was professionally tiled. It’s just a 2.5 x 4 foot area. The wall is painted plaster. I’m betting that there is lead paint below the current paint, so I don’t want to scrape it off. Would I have to replace this section of wall with backer board or is there an easier way to prep the wall? Many thanks!
Hi Phil,
If you thoroughly sand and prime the top layer of paint wall with, it should be okay to tile over without removing all the drywall. If the paint is sound and isn’t flaking, it should be fine to adhere tiles to it.
I am attaching 6×12 inch travertine ledgerstone panels to a previously painted brick fireplace. The surface of the bricks is very porous. I’ve sanded the brick surface and the remaining paint isn’t going anywhere. I’m using a modified thin set large tile mortar to attach the ledgerstone to the brick. Would the Mapei Eco Prim help the mortar adhere to the brick? Thanks for your advice.
Hi Mike,
Sounds like you have all the preparation done right. You won’t need to use Mapei Eco Prim for such an application, a regular acrylic tile primer will be more than adequate for the job. Just follow the instructions and make sure to dilute it to manufacturer spec.
Hello Carl, I just found this article and have a question. I am also going to tile over my brick fireplace. The brick is completely covered in paint. The following is my master plan:
1. Apply Eco Prim Grip to the painted brick
2. Apply modified thinset and install hardiebacker board (securing to the brick with appropriate fasteners)
3. Apply Eco Prim Grip to seal backerboard and provide extra grip strength for the mortar
4. Apply mortar and install tile
5. Grout tile
6. Rejoice in a job well done
My question to you – do I need to sand/rough up the surface of the brick prior to applying the Eco Prim Grip, completely remove all the paint, or just apply the Eco Prim Grip?
HI Kelly,
Sounds like a solid plan. If the bricks are pretty flat and level, you can skip mounting the hardiebacker and mount the tiles directly to the bricks.
Roughing up the paint is always a great idea as not only will it give the primer more grip to adhere to, it’ll show any flaking or weak paint that can be removed with a bit more sanding.
Goodluck with the project
Hi Carl,
Great page with tons of info! I can’t believe I just now stumbled upon it.
I’m tiling the second floor of a condo. I pulled up the old vinyl tile and scraped the adhesive. I’m not sure if the subfloor is gypcrete or lightweight concrete so I used Mapei Primer T. It says to use SLU within 24 hours but the floor is pretty level. Can I tile directly over the Primer T within that window or prep the floor with something else? Thanks!
Hi Drew,
Yes, it should be okay to tile directly over Primer T, within or after that window. I believe they’re just saying that in case you will be leveling with SLU, to level it within that window for best results. It’s just to prevent new dust, debris etc building up on the surface. Hope that helps.
Hola Carl Anders
Thank you for your time and for sharing your knowledge.
I want to decorate my outdoor columns with glass pieces (like glass tiles) by cutting each piece and create designs.
My concrete columns have a white paint or primer(not sure what it is) and plan to sand them to remove that material before applying the primer.
I’m not sure which primer should I use before applying the thinnest-mortar.
I live in south Texas where the columns are exposed to the extreme weather.
Hi Lulu,
You can use a standard acrylic primer for such an application after you have sanded the existing paint. Your choice of adhesive will be more important in this instance. Something like Ardex X77 is suitable for glass tiles and is also frost resistant so it should hold up to anything the weather will throw at it.
Hope that helps and good luck with your project.
How long after applying primer can it be left before the tiles are fitted?
It depends on how much foot traffic and activity is happening in the area but it’s usually good to start tiling within 24 hours of priming the surface.
Hi, I’m planning on tiling a wall in a bathroom . The wall is partially tiled already , I’ve bought matching tiles to tile the remainder . My question is , the wall is painted with bathroom emulsion but in very good condition . If I was to roughen up the painted area would this suffice or do I also need a primer ? TIA
Hi Janet,
Sanding the paint thoroughly should be enough for the tiles to adhere to. Just be sure to remove any dust leftover from the surface and to use a quality tile thinset suitable for walls.
Hi. I just removed 2200 sf of parquet that was glued (bruce parquet adhesive) down over concrete. We used a (ride-on LP scraper) machine to scrape up the wood and some glue. The remaining glue I scraped with over 200 4″ razors blades. I went over the whole thing twice. There is still some staining from the adhesive and in some spots, if you stand too long, your shoes will stick to the floor. Scraping these areas the third time results in a layer thinner than plastic wrap. The 90% of the slab will not readily absorb water. It sits on top as opposed to bare slab where it would get sucked in like a sponge. Which primer should be used?
Hi James,
That’s a huge effort! Congrats on getting all that done.
If I was doing it, I’d hit the surface with a grinder and diamond wheel to rough up the surface and help remove some of that glue. Once that’s done a basic acrylic tile primer will work great. You won’t need to use the more expensive Eco Prim on such a surface.
Hope that helps.
Hi Carl! Just found your site – awesome content and laughed at the line about drinking primer haha I am going to be putting some thin set on a painted drywall to achieve a concrete look and was wondering which primer you thought would be best. After reading your article I was thinking LevelQuick Acrylic but wasn’t certain. Thank you! Rob
Hi Rob,
I’m glad you enjoyed the joke! I knew that somebody would find it funny apart from me haha.
Yes, you are correct. A standard acrylic primer will be more than enough for painted drywall. Just check if the old paint isn’t flaking by running a spatula or putty knife over it and give the paint a quick sand. Then just apply the primer with a foam roller or brush. Should work out great!
Thanks for the comment and dropping by.
Good luck with the project!
Thank you for your help and follow up! The joke really gave me a good laugh! You really have created a great site with tons of info – so I’ll be reading more! Thank you! Rob
You’re a legend Rob. Thanks a lot for the positive comments and I’m very pleased my site is helpful and even a little bit entertaining! The internet needs more people like you.
Let me know if there is any other articles you’d like me to write!
All the best,
Carl.
Hi Carl I’m thinking of tiling over my kitchen tiles with bigger tiles, the original tiles are very shiny gloss type will the eco primer adhere to these tiles
Many thanks
Lee
Hi Lee,
Yes, you are correct. That’s the right primer to use for those tiles.
I’ve been dying to find someone who can answer a question on this subject, but no one seems to have the expertise demonstrated in this article! I have a very solid 5/8″ kitchen plywood floor in a 50s ranch house (joists 16 oc). I’ve removed the top layer of old linoleum and I’m left with a grayish paper-like layer which will NOT come off. It is quite smooth however and I can sand/grind down a few bumpy spots. It does not get soggy or pliable when thoroughly wetted down. I would like to use the Schluter Ditra uncoupling membrane and then tile.( I want to avoid raising the floor height with a clean layer of plywood. The Schluter handbook states that 5/8 is sufficient for tiling over Ditra.) I’m assuming the Mapei Eco Prim would do the job? Also, if 5/8 is the very minumum subfloor thickness, would it make sense to do some blocking between the joists for extra rigidity? I would REALLY appreciate your opinion. Thank you!
My bathroom floor is plywood over subfloor. The floor is rough in places and unlevel . I planned on cleaning, priming, leveling, priming, mastic, putting down not sure if hardy board or cement board, electric heat, tile mastic then tile then grouting. Not sure if I have the right order or stuff.. would really appreciate you putting me straight. Thank you. It has taken a couple of years to get to this point because of mine and my husband’s health. Can’t afford to hire anyone so it is a case of do it ourselves with arm power of family.
Hi Lynn,
It sounds like you are on the right track with the process – great work.
You will want to use some cement board over the plywood as it’s not a suitable substrate for tiling. So the process will be:
1 – cement board
2 – prime
3 – electric heat
4 – pour leveling compound (depending on your system, electric heat may go ontop of leveling)
5 – prime again (if electric heat is underneath leveling compound)
6 – tile
7 – grout.
Please do not use mastic adhesive as it’s not suitable for floors or heat. I would get a bag of flexible tile adhesive that is mixed with water and isn’t premixed. Your local home renovation/hardware store should sell some sort. Just ask the staff which one will work for your application. Usually these adhesives are the most expensive ones, don’t go with the cheapest as they are for concrete floors only.
I believe that’s everything. Let me know if you have any further questions.
Carl.
Hello tile guru I hope you can help and I am very sorry if I am bothering you. I have a laminate shower backsplash painted with acrylic high gloss paint. so it is very non-porous! What is the best prep to do to make it suitable to tile over, and what is the best adhesive for this job? Would greatly appreciate any help please and thank you.
Hi Dan,
No problem at all. If I didn’t want to be bothered, I wouldn’t allow comments 🙂
I’d sand off as much of the paint as possible and scratch up that laminate so the adhesive will have something to cling to. Then use Mapei Kerapoxy. It’s an epoxy grout that can be also used as a tile adhesive in situations like yours. I’ve worked over a plastic shower liner with Kerapoxy and it worked great (it’s designed to stick to it.)
You can then grout the tile with whatever you like.
Hope that helps, that’s how I would do it if I had to work over laminate shower walls.
Thanks for stopping by.
Hi Carl,
Thanks for your informative site. I’m a handyman with 40 years experience. I’ve done a lot of tile repairs in that time, and I have also done new installations. I currently have a job where my customers are “DYI” people. So, they want a new kitchen tiled backsplash wall, and they installed new greenboard and they mudded and taped the joints and then painted over it all with Kinzer 123 paint primer. I think I know the answer to this, but I’m running it by you first. I am uncomfortable with installing the tile by using mastic directly on the Kinzer-primed surface. I believe that I need to rough up the Kinzer primer with sandpaper and then apply a mastic primer over the Kinzer before installing the tile.
Your thoughts?
Thanks,
Tim
Hi Tim,
That’s spot on. Do exactly that and you shouldn’t have any issues.
Thanks for visiting.
Hi, I’m tiling my kitchen splashback with a 50mm x 20mm brick effect mosaic. The wall I’ll be tiling on is painted plaster. The paint is satin and is in good condition. What preparation do I need to do? Do I need to sand and score the wall then prime? If so what primer do I use? Also what adhesive should I use for white brick effect mosaic?
Hi Ainsley,
You can sand the paint to give the adhesive some grip and then prime with a standard acrylic primer. You can use pre-mixed mastic adhesive or a quality bag adhesive that is colored white. Just ask for it at your local hardware store, I can’t make recommendations on brands as I don’t know which area you live in.
Kitchen splashbacks are pretty easy in terms of prep and tiling, don’t over think it too much. Your choice of tile will provide some challenge though as mosaic requires plenty of care and some experience to get right.
All the best,
Carl.
Excellent article,
In my bathroom I’m thinking of degreasing, filling in the grout lines with filler, degreasing, then painting eco grip over the existing tiles, then painting over that with Zinnser Permawhite- To give a rough finish.
You think this would pose any issues? These are wall tiles btw, not submerged.
Hi 82-IU,
In theory that should work however you’ll be using the product outside of it’s designed specification. Tile primers are solely formulated to allow adhesives and levelling compounds to adhere to them, not paint. By all means you can try it, it should work but the paint might wear off faster than usual. Especially in wet areas.
Every flooring company and contractor I’ve talked to say you cannot use an epoxy based primer or oil based primer before putting the thin set down and installing the tiles. Your product is epoxy based correct? These people say that the tiles will not last 2 weeks.
Hi David,
Not sure where you read this in the article. None of these primers are epoxy or oil based.
Also, none of these products are mine, they are manufactured by reputable companies that specialise in tiling products.
I can see there is some confusion here so just go with whatever your local flooring companies say.
Goodluck with the project.
Hello Carl, I’m tiling a plaster wall in our bathroom. The top/white coat of the plaster came off with the old tile removal leaving the plaster brown/gray coat underneath. I have primed with Zinsser BIN shellac based primer in preparation for new tile. Is that primer good enough or do I need something else? Do I need more than one coat of primer?
Thanks Mark
Hi Mark,
I’m not too familiar with this primer, from reading the spec sheet it looks like a very robust primer for stopping stains from coming through. From what I understand, you should be fine to tile if it’s not in a wet area (like inside the shower stall.) To be safe I would sand the area with a fine sandpaper to give the adhesive some grip and go from there.
All the best with the project,
Carl.
Hi Carl,
I am going to be applying stone ledger panels to an existing fireplace that has painted brick. I am also extending this all the way up to the ceiling. I have built out a frame and attached cement board to the framing above the brick. I need to level out the brick with a layer of thinset first to get an even surface. What primer would you recommend for me to use for this project. Is it ok to put a layer of primer over thinset and cement board?
Thanks,
Matt
Hi Matt,
A standard acrylic primer will do if you rough up the existing brick and remove as much paint (if the brick is painted.) Mapei eco prim can be used if the brick is heavily painted. Once the backer is one, definitely prime it with the primer again to avoid it sucking up the thinset’s water too quickly.
Hi Carl,
Thank you so much for all the great information! I’m looking for U.S.-available products comparable to “Omnicem PL85” (a powder adhesive), “Omnibind TP” (a primer I believe) and “Omnifill 102” (a water-resistant grout for thin joints). This is for cement tiles hand-made in Morocco, see here: https://www.emeryetcie.com/en/catalog/tiles/cement-tiles/laying-and-maintenance/ The company says Mapei makes equivalent products. Do you know which ones are the equivalents to these international products? And one of your comments above suggests using the adhesive, not the primer on the back of the tile but the instructions for this tile suggest using the primer on both surfaces to also seal the tile and then apply the adhesive to both surfaces. If you have any thoughts about that I’d be curious to hear. Thanks again for all your great tips and information!
Hi Tamara,
I would suggest you follow the manufacture instructions as they may have a certain process that needs to be followed to enable their tiles to adhere properly. Unfortunately I have never worked with these tiles nor with the products recommended so can’t comment with factual advise.
Primer can be applied to the back of porous tiles to prevent them from sucking up the water from the adhesive too quickly. A primer will seal off the tile and prevent it from absorbing too much water. Once it’s dry, you apply adhesive to stick it to the wall/floor.
The tiles you have are cement tiles that require sealing with a waterbased sealer like Stonetech Bulletproof. Both front and back sides. You can then use a suitable tile adhesive for your substrate. Grout choice is up to you. If you choose to use epoxy grout, you’ll need to do a spot test first as some cement tiles can get picture framing if not sealed properly.
Hi Carl
I am wanting to tile a shower enclosure that is completely lined with toughened glass with coloured backing similar in appearance to a kitchen backsplash . Can I use Mapei Eco Prim and simply tile over the top of the glass?
Regards Pete 🔨
Hi Pete,
I guess it can be done but I wouldn’t do it professionally due to it being a wet area with steam. These components may affect the Eco Prim and cause it to loose adhesion over time. Of course I’m thinking about my warranty and liability. As a homeowner you don’t have those concerns and can just go ahead, chances are nothing will happen and your tiles will remain intact for decades.
I would scratch up the glass thoroughly with some fine grit sandpaper to really give that Eco Prim a great surface to cling to. Degreasing the glass to avoid any soap scum and body oil is a must as well. Lastly, use a premium powder adhesive – not mastic – as your glue. Epoxy grout would also be a good choice to really give the installation some strength and ease of maintenance.
Thanks for your expertise. I’ll be using 12×12″ porcelain tiles on cement. Half of the 240 sq. ft. area is new cement; the rest is old and has vinyl tiles and horrible adhesive to remove. Does absolutely all the (water-based but still awfully persistent) adhesive have to be removed prior to the primer? My other question is, I’m concerned about cracking of the tile floor since my area has some train vibration, and would like to use an anti-fracture membrane like RedGard. Do I need to use tile primer AND RedGard, or could I just use RedGard and no primer, since RedGard both blocks moisture and helps reduce potential cracking? Lastly, does ALL the adhesive from old vinyl tiles have to be removed to use RedGard? Many thanks!
Hi MP.
The old adhesive doesn’t need to be fully removed. You can scratch it up with rough sandpaper and then wash it with a degreaser. Ideally a grinder with a diamond cup wheel would be ideal but not necessary. If the glue is stuck down properly and there aren’t any large chunks that’ll deflect your tiles, you should be fine to go over the top.
Yes, you’ll need to use a primer before applying Redguard. The primer will ensure your Redguard adheres to the cement and doesn’t peel off once you begin walking over it. This is a common mistake. A primer is your best friend in flooring and can be used before anything is applied. RedGuard, self leveling compound, mud bed, etc. It arrests dirt and dust and also prevents your substrate from sucking up the water from your products. A lack of moisture during curing equals to a failure to adhere to the surface and a weakened product overall. So yes – use an acrylic primer before applying RedGuard.
Hope that helps,
Carl
Hi Carl,
I’m tiling a kitchen with porcelain tiles. Used to be hard wood flooring. Underneath is concrete that was sealed. It’s not glossy or shiny. Can we use Mapei Prim Grip on this concrete floor to lay ceramic tiles over?
Thanks!
Hi Demetrios,
You won’t need to use Eco Prim, just a basic acrylic primer for tiling should work fine for your application. Eco Prim is more for tiling over old tiles and you require that extra grip.
Hope that helps,
Carl
I am planning on 6×6 ceramic applied to drywall outside/around shower and around bidet, toilet, and freestanding tub. Drywall currently has wallpaper. Question – Is it necessary to remove wallpaper before tile ?
Hi Dale,
Since you’re working in a wet area that is subject to steam and moisture, I would remove the wallpaper or as much as possible to hit the drywall. Remember that you’re tile will essentially be stuck to the wallpaper, if that fails due to trapped moisture, your tile falls off along with the wallpaper.
It’s an added step in the process but if you want your tiles to last for decades, an extra days work is well worth it.
Hi there Carl,
What a great article. My 12×12 inch ceramic tile shower floor is getting a 2×2 inch tile overlay. Original plan (not my preference but it is what the builder will pay for) was to use Redgard for the tile on tile installation for added waterproofing and crack prevention. When the contractor arrived without the Redgard, I panicked. They insisted on instead using the Custom MBP primer and no Redgard. I want the best outcome as the home is still settling and I don’t want cracks and separation where the floor meets the wall in the shower and between tiles (which has happened within a year of construction). I am a little worried because they didn’t do anything to the substrate surface to rough it up other than apply two coats of the MBP primer 3 hours apart.
Should I press them to apply the Redgard before the Thinset and subsequent tile/grout installation? This is my master shower and it gets lots of use! Any advice on this? What would you recommend in this situation? THANKS IN ADVANCE FOR SHARING YOUR EXPERTISE!!!
Hi Kai,
I’ve never come across an instance where you coat MBP with Red Guard. Since you are keeping the existing tiles, there should be a waterproofing installed underneath them, hence making your shower waterproof. (IF you’re shower was installed correctly – some don’t waterproof.)
At the end of the day, the best solution is to tear everything back to the stud and do everything properly. I understand the budget may not be there for that however. If you did your due diligence and hired contractors that are insured and qualified then you shouldn’t have any problems.
In terms of grout, if you want the best long term solution – go with Epoxy grout. (Unless you’re using pebbles or small stones in the shower base.) Epoxy grout will be easier to clean, make the whole installation stronger overall and also add a higher degree of waterproofing. (Water won’t penetrate the grout line.) It does cost more so discuss this with your contractor first and see the differences in price before going with epoxy or regular grout.
Oh I forgot to ask if there is a special type of grout that should be used for shower floor?
Carl,
I want to put tiles on a balcony. The surface of the balcony is covered with a Tremco (an American company) 351 membrane and I am looking for
a primer that will bond with the membrane..Once the balcony is primed I will then install the titles to give a better look.
Can you suggest a primer that will bond with the membrane and also the glue which will be used to stick the titles
Thanks.
Hi Grame,
Unfortunately I don’t have experience with Tremco but with any construction product, the best course of action is to call their technical helpline and ask what they suggest. They always have a list of products and instructions on how to use their products. On their website, you can find a local representative as well.
I hope you find the information you need.
Carl my son had black mastic in his rec room it’s very thin . we sealed it with a water based acrylic sealer product designed for asbestos like a paint . Now I’m reading it’s not a good idea to tile over a painted floor. I am doing a test spot with one tiles check for Adhesion . Do you recommend a product to apply over the sealer prior to thinset ?
Hi, I’m tiling over laminate countertop and was planning on using the MBP primer because of the aggregates, but then noticed its water based. That gave me pause because obviously thin set is mixed with water! Is that a valid concern or am I overthinking it? Thanks/Mark
Hi Carl, I’m working on tiling backsplash in my kitchen. Got a 100-yr old house with plaster walls. The paint behind the old backsplash was positive for lead, so I’ve applied thick coats of lead-encapsulating paint that I don’t want to sand. Also, the wall is uneven with relatively thick pieces of material that were probably used in past jobs, but I’m afraid to scrape off. Recommendations on how to prep walls? Can I use Sheetrock Plus 3 Joint Compound to smooth the wall and then apply a multisurface bonding primer over it?
Hi Carl.
Great forum. I am tiling onto a concrete patio. Have used the correct primer, but due to been laid up with a bad back and then a holiday, this was four weeks ago. do I need to prime again?
HI Ricky,
If you have the primer laying around then I’d quickly brush on a new coat just to be sure. It’s a few minutes work for a job that’ll last a lifetime.
Hi carl- i am so overwhelmed by different answers from other sites. Could you please help? We installed 1/2″ regular drywall for a kitchen backsplash. We are hiring someone to tile. I’ve read that thinset morter is better. So here are my questions- what brand primer?- prefer water based due to odor of others- how may coats and do you sand afterwards/ in between coats if more then one? – what brand of thinset is best and premix or add water? we are planning on ceramic or porcelain tile. Also read that you need to let drywall cure for a month before tiling. We have one small joint about 12″ so does that need to be taped and mudded then sanded? Also have a few screws a bit deep- fill those in or not? Best grout and premix or not? And best silicone for sealing to top of countertop built in backsplash ( laminate) where tiles end. Should inside corners be taped? Best tile sealer? Phew!!! Lot of questions but need lots of advice- anything else you would suggest? Thanks
Hi Daphne,
If you’re hiring a tiler to install the tiles then you shouldn’t be concerned about these details. I’m not going to say what products they should use as that’s disrespectful and intrusive on their methods. At the end of the day, their word is above mine as I’m just a voice on the internet whilst they are a real, physical professional who can assess the work and understand what’s required.
Hi, We recently had a shower added to our bathtub. Now I want to put ceramic tile on top of painted plaster. The home was built in 1927 so I’m sure there’s lead paint under the two coats of paint I have applied in the last 20 years. My question is, can I put ceramic type on this and if so, what sealer and primer do you recommend? Also, would you recommend epoxy grout ? Praying you don’t tell me I have to rip it all out. Thank you for all the helpful information. I want to do it right, but certainly can’t rip out plaster walls on my own.
Hi Carl I have a kitchen floor that has linoleum on it that I believe has asbestos in it, my plan is to clean linoleum use a primer and then use uncoupling membrane to lay ceramic tile, the tile is super tight to plywood, there’s one layer, and I don’t believe that it is cushioned, is there any reason to believe this won’t work,thanks!
Hi Mike,
That sounds like a solid plan and it’ll help alleviate any problems with the asbestos. Just be sure to use the recommended adhesives for the uncoupling membrane and you should be fine.
Hi Mike, I have a customer that has asked me to tile some outdoor block walls in various sizes of slate.
Which primer would you recommend ?
Kind regards
John
Thank you for this great site – it is so appreciated! Ok – doing a tile over tile in my shower. I am using the Mapei Eco-Prime Grip and did apply and let dry for a few hours. Then on a recommendation – I also applied 2 coats of the Mapei Aquadefense. I started tiling using the Keraflex Plus mortar. Got about 5 rows in on the back wall and finished for the day. I also used Spin Doctors for leveling. I came back in the afternoon and started to ‘bang’ off the levelers – and a few tiles popped off. I am going to chalk that one up on not mixing the mortar correctly (seemed wet enough) – but, since I’m new at doing this – I think that the mortar sat for too long and dried out. As I started to clean up the areas that the tiles came off of – the Aquadefense started to come off w/ the mortar. Well, all of it came off – Eco-Prime and Aquadefense…uhg. My main question is – do I need to do the Aquadefense? Seemed like the Eco-Prime was fine and dandy – just didn’t know if I needed the extra waterproofing…..cheers!!!
The tiles should definitely not be popping off after you removed the spin doctors. I believe you had poor adhesive coverage on the tiles and were barely holding on to the substrate. Your preparation sounds fine. Are you buttering the backs of the tiles with adhesive before setting them?