Do I Need To Seal Cement Board before Tiling: 7 Points to Know

Last Updated on January 8, 2023

Sealing cement boards before tiling has been a key part of the tiling process for many years. This is because sealing cement boards offers numerous advantages that result in a more durable, water-resistant tile installation.

Among these advantages are an increase in the strength and durability of the tiles, as well as a reduced risk of moisture damage to the sub floor or walls below them. However, there are also some drawbacks to consider when it comes to sealing cement board prior to tiling. 

These include the additional time investment and cost required for sealing processes, difficulty reaching hard-to-reach areas such as corners and joints beneath cabinetry, potential damage due to incorrect application, and regular maintenance needs if sealants wear out too quickly.

As such, it is important to know what type of sealant best suits your tiling project before beginning work. 

Advantages of Sealing Cement Board before Tiling

Increased Water Resistance

When it comes to tile installation, nothing is more important than ensuring proper waterproofing. By sealing cement boards before tiling, you can increase the water resistance of your finished product and ensure that your tile installation lasts for years to come.

Sealing not only helps keep water from seeping through the substrate and damaging the underlying area, but can also make your tiles easier to clean and maintain over time.

Additionally, sealing will help extend the life of your tile installation by preventing staining from dirt and grime build up as well as protecting against mold growth due to trapped moisture underneath your tiles. 

Enhanced Durability and Strength of the Tile Installation 

Sealing cement board prior to tiling helps prevent movement between the boards, which in turn helps give your finished product greater strength and durability than if it were installed without being sealed first.

Additionally, when done properly with high quality sealants specifically formulated for use on cement boards, it will help protect against cracking or other structural damage caused by heat or cold weather conditions that could otherwise damage your tile installation over time. 

Reduced Risk of Moisture Damage to the Subfloor or Walls below the Tile Installation 

In addition to strengthening and protecting your finished product itself, sealing cement board prior to tiling also helps reduce any potential risk of moisture damage occurring beneath or behind it.

By keeping out excess moisture that could otherwise seep through gaps or cracks in untreated boards, you can prevent costly repairs down the line due to any water damage that may have occurred had you not taken this precautionary measure beforehand.

This will not only save you money in repairs but will also help provide peace of mind knowing that you have taken all necessary steps in protecting your property from potential water damages during a tile installation project.

Disadvantages of Sealing Cement Board before Tiling

Added Expenses and Time Investment Required for Sealing Processes

One of the main disadvantages of sealing cement boards prior to tiling is the added expense it can incur. The cost of sealant materials varies widely depending on brand, type of sealer used (e.g., acrylic versus urethane), size of container purchased (e.g., gallon versus quart), and other factors.

As a result, it may be necessary to purchase several different types or brands of sealers in order to complete the job properly. Furthermore, additional labor is involved in applying the sealant; if done by hand rather than with a spray gun or roller applicator, this could add even more time and cost to the overall project.

Finally, as with any DIY job involving chemicals or hazardous materials like sealants and primers, proper safety measures such as gloves and respirators must also be taken into account when budgeting for the project’s costs. 

Having trouble sealing hard-to-reach areas such as corners and joints in the boards & under cabinetry

Another disadvantage associated with sealing cement boards before tiling is the difficulty in reaching certain areas that require attention during the process. Corners and joints between two pieces of cement board can be especially tricky because they are often tucked away beneath cabinetry or other fixtures that are difficult to access without specialist tools such as flexible scrapers or putty knives.

Due to their awkwardness and tightness within spaces like these, these spots may not be adequately sealed unless extra care is taken during application leading to additional labor costs as well as an increased risk of failure at these critical points that could lead to water damage down the line. 

Potential Damage to Finishes or Other Materials if Not Applied Properly

The application process itself can have its own set of issues if not done correctly; improper coverage due to incorrect application techniques can cause discoloration or other damage over time on finished surfaces surrounding your tile installation area (such as wooden cabinetry).

This makes choosing a reliable applicator all that more important since an inexperienced contractor could potentially sacrifice quality for speed resulting in costly repairs down the line should something go wrong with your tile installation due to mistakes made when attempting to apply sealer around it beforehand.

Additionally, some types of primer used beneath certain types of sealant may also cause discoloration on finishes adjacent it; therefore care should taken when selecting which product you plan on using here too! 

Additional Maintenance Can Be Necessary if Sealants Wear Out Too Quickly from Use over Time

Finally, another disadvantage associated with sealing cement boards prior to tiling is that regular maintenance may become necessary over time due to wear and tear caused by everyday use in wet areas like showers or even just general moisture exposure caused by humidity buildup near heavily used sinks/bathtubs etc.

Depending upon how frequently sealer needs replaced (every 3-5 years would generally be recommended), this maintenance work could lead to added costs that weren’t initially planned for during budgeting stages – especially since re-sealing may require careful removal/replacement procedure which takes up additional labor hours too!

It is always advisable then that you choose higher quality products from reputable companies when first purchasing your items so you don’t have worry about having repair this part later down line due premature failure seals!

Technical Considerations for Sealing Cement Board Before Tiling

Technical Considerations for Sealing Cement Board Before Tiling

What Type of Sealant Best Suits Your Tiling Project?

When selecting the type of sealant for your tiling project, there are several technical considerations that must be taken into account. The first factor to consider is the material of the surface you plan to tile on. For example, if you are tiling on cement board, then a specialized sealant designed specifically for use with cement board would be ideal for your project.

There are various types of sealants available for different tile projects such as epoxy and latex-based products, silicone caulk, and urethanes. All of these types of sealants have their own unique benefits but selecting one that is appropriate for your specific tiling project will ensure maximum protection and a successful outcome. 

In addition to considering the substrate material, it is also important to consider the location of your tiling project. If you are laying tiles in an area that is prone to moisture or in direct contact with water (such as a shower), then it is highly recommended that you use a waterproofing membrane along with a sealant designed specifically for use in wet environments such as silicone caulk or epoxy grout.

On the other hand, if you are working on an interior wall or other relatively low-moisture environment then a latex-based product may be suitable. 

Finally, when selecting the type of sealant for your project it is important to consider any additional features that may be required such as flexibility or crack bridging ability.

For example, if the tiles you are installing cover large areas then it would be beneficial to choose a more flexible sealant so that it does not crack over time due to movement or settling beneath the tiles.

Likewise, if there is an increased risk for cracks forming where two tiles meet then choosing an adhesive with crack bridging abilities may help prevent this from occurring. 

How Much Sealant Is Needed for a Given Projects?

The amount of sealant needed for your given tiling project will depend on several factors including the size and shape of tiles being used, number of joints between tiles and substrates (if present), and porosity within existing substrates (if applicable).

A general rule of thumb is to use 1/16” thickness per linear foot when estimating how much sealer will be needed; however it is important to note that some substrates may require more than this depending on their level of porosity or after applying any necessary underlayment materials prior to sealing.

Additionally, when calculating how much product will need to be purchased it can also help save money by accounting for any wastage during application and clean up processes; this can help avoid costly mistakes at the end stages of the job. 

Does the Waterproofing Membrane Have To Dry Before You Can Apply Tile?

Yes – before beginning any tiling work it is essential that all waterproofing membranes used have fully dried before attempting any installation; this includes both self-leveling membranes and coatings as well as traditional sheeted membranes such as asphaltic based products applied using mastic adhesives.

Failure to do so can result in improper bonding which can lead to leakage issues in high moisture environments like bathrooms or kitchens where water contact could occur easily; this could even lead to mold growth in extreme cases which can become very costly over time if not caught early enough!

As mentioned previously when applying self-leveling membranes always leave them undisturbed overnight before commencing any tile installation work so they have adequate time dry out properly which should ensure proper adhesion between layers once finished installation process has been completed successfully afterwards

Different Methods for Applying Sealant To A Cement Backerboard Surface

Brush On Method (For Small Projects)

When applying a sealant to a cement backerboard surface, the brush on method is ideal for small projects that don’t require a significant amount of coverage. This method involves using a paintbrush or foam brush to spread the sealant across the surface.

The brush should be chosen based on the size and shape of the area being coated, as well as the type of sealant being applied. If a thick sealant is being used, an angled brush may help spread it out evenly.

When using this method, it’s important to make sure that each stroke of the brush covers an even layer of the sealant over the entire surface. If there are any gaps or dips in coverage, they can compromise the integrity of the sealant’s ability to protect and waterproof the cement backerboard surface.

It’s also important to make sure that brushes are regularly cleaned throughout application in order to avoid any clumping or unevenness due to dried sealant on them.

Roller On Method (For Larger Areas)

The roller-on method is best used for larger areas where more coverage is needed in order to ensure an even layer of protection is applied throughout all areas of contact between the cement backerboard and its surroundings.

This method involves selecting a roller with an appropriate nap size for use with whatever type of sealer you’re using, then lightly rolling it across the surface from one end to another until it is completely covered in an even layer. It’s important not to apply too much pressure when rolling so as not to push too much product into any crevices or leave behind unwanted lines or ridges in your finished job. 

The roller-on method is advantageous because it allows you to cover large areas quickly, however care should still be taken when applying it especially around edges and corners where more attention needs to be paid in order to achieve complete coverage without leaving any exposed areas vulnerable.

Additionally, different types of rollers may need special treatment if they are going to be reused such as cleaning with mineral spirits after each use and/or storing them properly in order maintain their condition over time and get optimal results from future applications as well as saving time on cleanup later down the line. 

Spraying Method (For Even Coverage)

When aiming for complete and even coverage across a large area, spraying can be an efficient way to accomplish this task by creating a thin film over every square inch without having to worry about manually brushing out each individual area that would take far longer when done manually with either a paintbrush or foam roller method .

Spraying can also be used for smaller projects such as coating undulating surfaces like corrugated metal sheets or ceilings with low clearance which could prove difficult when attempting other methods listed previously due its high speed capabilities allowing you apply multiple layers quickly and easily .

When executing this technique it’s important o note that overspray is common so proper protection should be taken beforehand such as taping off nearby surfaces beforehand along with wearing protective clothing while operating equipment.

It should also go without saying that proper ventilation must always be maintained while spraying indoors due potential hazards presented by inhalation solvents contained within products which can cause long term health issues if not dealt with correctly.

After completing job intended ,next step requires thorough cleanup machines components along with all surfaces affected by overspray prior moving onto next project .

Can You Tile Directly on the Cement Board?

Can You Tile Directly on the Cement Board

Yes, you can tile directly on top of a cement board as long as it has been properly sealed with an appropriate sealer. Generally speaking, it is best practice to use a latex-based sealer that has been especially designed for use on cement boards.

This will help to ensure that there are no gaps between the tiles and the cement board that could result in water seepage, leading to costly repairs down the line. Furthermore, this type of sealer also helps to prevent grout from staining or discoloring the underlying surface. 

How Do You Waterproof Cement Board?

The best way to waterproof cement board is to apply a water-resistant sealant over its entire surface once it has been installed and before any tiles are laid down. This should be done prior to tiling in order to ensure maximum protection from moisture damage.

It is important to choose a sealant that is specifically designed for use on cement boards as these products contain additives that will better bond with the substrate and form a tighter barrier against moisture intrusion. 

How Do You Seal Cement Board Seams?

Once all of your tiles have been laid and grouted, there may still be some small seams between pieces of cement board which need to be sealed in order to ensure complete protection from water damage.

To do this, simply apply another layer of water-resistant caulk along all of the seams between pieces of cement board using a caulking gun or brush. Make sure that you smooth out any excess material with a damp cloth and allow it time dry completely before continuing with any other work on your project.


Whether you decide to seal your cement board before tiling or not, it is important to take into consideration all of the technical aspects involved in order to ensure the best possible outcome for your project.

By understanding the advantages and disadvantages associated with sealing cement board prior to tiling, you can make an informed decision on which route will best suit your needs. With this knowledge in hand, you can confidently install tiles that will look beautiful and last for years to come!

About the author

Leave a Comment