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Planning on starting a tiling project but not sure how to prep your surface? Or maybe you have heard about tile primers and have no idea what they are and whether or not you need to use em?

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.

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?

If you don’t use a tile primer, you face the risk of your tile installation failing prematurely. Anything from 3 months onwards, depending on the amount of track.

I’ve seen this time and time again and when I lift a tile up, it comes clean off the floor and you can see that the substrate is immaculate – no thinset has ever touched it, even though it was technically applied on it.

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.

A tile primer is a liquid tiling product which is used during the surface preparation phase. It is primarily based on latex, polyurethane or epoxy and has the general viscosity of plain water, depending on the type.

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). 

In essence, a primer is the first step in a tile installation.

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.

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 you apply a tiling primer will depend on whether you are using an acrylic or resin based primer as the thickness of those products is different.

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 Henry 564 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.

While every manufacturer has their own instructions on how to use their product, there are a few steps that apply to every product.

4. For highly polished concrete floors, mechanical scarring may be needed in order for the tile primer to penetrate it. Use an angle grinder with a diamond grinding wheel to scuff up the surface.

5. Once all preparation has been completed, start from the wall furtherest from the door and make your way backwards. Work slowly and methodically to cover the whole surface area with tiling primer.

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 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. 

There are two main types of tiling primers that you may require for your tile preparation work.

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. 

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. 

View Manufacturer Info Sheet. 

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.

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!

View Manufacturer Info Sheet – View FAQ 

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.

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. 

They can 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! 

View Manufacturer Info Sheet

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 1:1. For example 1 quart of primer to one quart of water.

Coverage:

100 to 150 sq. ft. per quart/9.3 to 13.94m2 per 0.9 litres.

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 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.

All primers say that they require atleast 3-24 hours to cure properly. Substrates that are porous will help the primer cure quicker.

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.

Let’s face it, tiles are expensive.

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. 

All the best for your next project, remember to have fun!