If you are planning to tile your kitchen backsplash or the walls in your bathroom, there are a few things you will need to do to ensure the job goes smoothly.
Without the correct preparation, you may have loose tiles or a mold and mildew problem.
Primer is usually applied to porous surfaces before being painted, but do you need to prime drywall before tiling?
If you are tiling over unpainted drywall, you must apply a primer first to ensure proper tile adhesion. For painted drywall, you do not need to use a primer before adding tile because the surface was sealed before it was painted.
Ensuring the drywall is primed and sealed before tiling will prevent issues with tile adhesion and future damage from moisture or heat.
Keep reading for more information on why priming your drywall before tiling is important.
What Is Primer?
Primer is a product used on drywall or other porous surfaces before painting or applying tile.
The primer helps seal the drywall to prevent moisture from seeping into it and forms a bonding layer.
This bonding layer increases the surface energy of the drywall and allows the paint to adhere to the wall so it does not peel away.
Without a primer, drywall is prone to mold and mildew growth, and damage from heat and sunlight.
Primer is also used to cover stains in drywall when there is no way to remove them.
Reasons for Priming Drywall Before Tiling
Many people assume they only need to apply primer to their drywall if it is going to be painted, but this is simply not true.
Ensuring your drywall is primed correctly before installing tile is the most critical step in the entire process for various reasons.
For Proper Tile Adhesion
The porosity of drywall means it will absorb the solvents in the glue you are using to adhere the tiles to the wall.
This is not ideal, as most glues rely on the solvent evaporating slowly during the chemical reactions as they dry.
If the solvent evaporates too quickly, the glue will harden, and adhesion will be compromised.
The drywall and the tile bond will be weak and result in loose tiles, which may separate from the wall completely and fall off.
Applying a primer to the drywall before tiling will seal the wall’s porous surface and give the glue a surface to bond to
To Prevent Mold and Mildew From Forming
Since drywall is so porous, it will not only absorb the solvent in your glue but will also retain moisture.
Once the moisture has seeped into the drywall, it becomes a breeding ground for mold and mildew.
This creates a significant problem, especially since most tiles are installed on bathroom walls where moisture is abundant.
Mold will cause several allergy symptoms, and repeated exposure will increase a person’s sensitivity, leading to more severe reactions.
Symptoms of mold exposure include:
- Runny nose
- Watery eyes
- Difficulty breathing
Priming the drywall helps seal the porous surface and prevents moisture buildup, reducing your chances of mold growth.
If you are tiling a shower, you will not be placing the tile on drywall.
Installing the tile directly onto drywall in a shower will cause severe mold and mildew problems in your wall, no matter how well you prime and seal it.
For areas with a lot of moisture, such as a shower, you will attach the tile to a cement backer board.
The cement board will also need a vapor barrier underneath it, and you will need to use moisture-resistant tape to seal any seams.
To Protect from Heat and Sunlight
Temperature is another important factor in the effectiveness of your adhesive.
If you do not prime your wall before installing tile, sunlight and hot temperatures will begin to weaken the adhesive.
Primer contains polyvinyl acetate, one of the ingredients in carpenter’s glue.
The polyvinyl acetate makes the primer moisture and heat resistant.
Because of the similarities in the chemical makeup of primer and glue, there will be a strong bond between them.
This bond will prevent your tiles from becoming loose and possibly falling off the wall.
To Increase the Surface Energy of the Drywall
High-strength adhesives have high surface energy, which makes them incompatible with drywall because it has much lower surface energy in comparison.
Applying primer to drywall increases the surface energy and allows the tile adhesive to form a stronger bond.
This bond ensures the glue will dry properly, and your tile will stay in place.
How To Apply Primer to Drywall Before Tiling
Before tiling your wall, there are several steps you will need to take to prepare your drywall.
If you have just installed the drywall, it is crucial to wait at least one month before tiling it.
When you tile fresh drywall too soon, you may end up with cracks or other structural issues in your wall.
The first thing you will do is thoroughly inspect your drywall to ensure it is firmly secured to the studs.
Use drywall mud and tape to seal seams and allow the wall to dry.
Related: Make taping easier with a banjo.
Medium-grit sandpaper will be needed to sand the seams and smooth out any uneven areas.
The drywall surface does not have to be perfect since it will be covered with tiles, but it still needs to be smooth enough for an even application.
Remove any dust with a damp sponge and allow the wall to completely dry before applying the primer.
Apply a coat of primer to the wall with a fully-loaded paint roller, and work in small sections from top to bottom.
Once the primer is applied, you will have to wait until it is totally dry before adding your tiles.
Any damp areas will prevent your tile adhesive from sticking to the wall.
When you have ensured the primer has dried, you may begin to apply an adhesive layer and start placing your tiles.
It is always a good idea to plan your layout ahead of time so you do not have any issues with tile placement.
It is best to wait until your tiles are fully set before you grout them, or they will move, and your grout lines will be uneven.
Related: How many coats of primer on drywall?