Should Backer Board Touch Shower Pan?

Should Backer Board Touch Shower Pan?

Note: As an amazon associate I may earn a small commission from qualifying purchases if you click to amazon from my site and choose to make a purchase.You can read my complete affiliate disclosure for more details

Should Backer Board Touch Shower Pan?

A shower pan is a rectangular piece of material placed at the bottom of a shower. It can comprise different materials, such as fibreglass or cast iron.

I sometimes refer to a shower pan as a “shower base” or “bathtub.”

No. You should have nothing touching your shower. Things like the backer board and even tile may not touch the shower pan when it comes to your shower. If you ever encounter a situation where something was touching the shower, you should probably replace that item altogether, as it’s already compromised.

The whole reason for this is safety. If something touches your bathroom floor, you have nothing to stop an accident and falling onto it.

However, there are exceptions to this rule. One of these exceptions is under your tub. Suppose you have a tub and want to put something under it.

It will be outstanding if you put something under the actual tub because it’s such a heavy object that there are no chances of it falling on its own, even if there was nothing under it.

But make sure you’re not putting anything under your shower like a shower curtain or a shoe organizer.

The only issue you could encounter if placing something under your shower is mold. Let’s say you live in a humid area.

If the thing you put under the shower starts to rot, then there’s a chance it could ruin and leak your floor.

But this method should be exemplary if you’re not too worried about mold and rot. But make sure it’s not touching your shower pan at all.

Should The Cement Board Overlap The Shower Pan?

Yes. You absolutely should, and here’s why. A cement board is a layer of cement between the horizontal base of the shower floor and the pan that holds water.

This water-resistant barrier is one of the most important parts of building a new shower because it protects your walls from damage caused by condensation or leaks.

Water stains would ruin your walls and ceilings if this layer weren’t there.

If your cement board is not overlapping the pan, remove some wall covering to expose the cement board. Suppose it’s drywall; pull it off.

If it’s pressed wood, look for a layer of gypsum board under the pressed wood and take it down.

You will probably find some insulation in the wall, but this is okay because it will keep your shower warmer and save energy.

If your shower walls are concrete, take them down. Ensure you don’t destroy the floor, and be careful not to hit pipes with a sledgehammer. This can bend them or even break them.

Hold the sledgehammer level on the floor to hit the center of the wall very close to the edge.

Does The Backer Board Go Over The Shower Pan Lip?

Yes. You can use a backer board over a shower pan lip. 

There are two ways to accomplish this. The first is by cutting a hole large enough for the floor lip in the shower pan and then placing a backer board over that hole.

This can prove more challenging than necessary, but using plastic edging as a secondary step provides a solid transition between the two surfaces.

Should Backer Board Touch Shower Pan?

Alternatively, you can place the backer board on top of the existing shower pan material and have it slope slightly downward toward the floor lip to create an opportunity for water to run off.

As with any tile project, you’ll want to use thin-set mortar and silicone caulk to facilitate bonding backer board onto the surface of the shower pan.

Use transparent silicone because white will be difficult to cover with grout.

You can also use a grout float by applying thin-set mortar over the edge of the backer board, then applying silicone over that.

Or, you could apply a thin bead of silicone and the thin-set. Finally, ensure you apply epoxy grout over your new tile.

How Close Should The Cement Board Be To The Shower Pan?

1/8 inch above the shower pan. That seems to be about the standard. However, that’s “standard” for a lot of different people.

1/8 inch over the shower pan is probably too high on a first-floor front porch. But if you are in an attic with a downspout on your back porch, you might not want to measure from there because it’s higher than most people would measure.

Some people think that 1/8 inch over the lip is fine for a couple of inches, but then it no longer covers the corners of the shower pan.

So, they think 1/4 or even 1/2 inch over the lip is better than 1/8, but they don’t want to put it over.

I’ve seen some people cut a piece of Formica or veneer to fit between their tile and shower pan if there was enough gap at the back (or sides).

I once tried this and ended up cutting a piece of 1/2 inch plywood and gluing it to the Formica below the shower lip, and I find it easier to clean all around that way.

Some people use wax paper instead of tiling the corner. That’s messy, though–I think it would not be easy to clean properly.

How Do You Install A Backer Board On A Shower Pan?

Installing a backer board in a shower pan is a relatively straightforward DIY project that provides many benefits.

Besides constructing a waterproof surface, installing a backer board in your shower will allow you to upgrade your space and add more storage.

It can make your life simple and save you money in the long run. Follow the steps below to install a backer board on a shower pan.


  • Shovel
  • Tape measure
  • Screwdriver (flathead, Phillips) and drill bit (3/16th inch) (optional)


  • Installing Shower Pan Backer Board, A shower pan is a waterproofing material typically milled from polyethylene plastic or polypropylene.

Prep the Shower Pan for Project: Remove any old caulking, caulk, and sealant that one may have applied to your shower pan in the past.

  • Carefully cut the backer board to fit your shower pan by carefully measuring and cutting through the plastic coating on the face side of the backer board with a utility knife or a Sawzall.

Remove any excess plastic material from around the edge of the backer board with a utility knife or an X-Acto knife before installing it on a wet surface in the shower pan.

  • Think about where you will place the shower curtain rod and mark the center of your shower pan where you want it installed.

Place a straightedge over the line to run parallel to the edge of the shower pan, and mark a line along both edges of the straightedge using a pencil.

  • Center the backer board over this line and press down firmly with your hands until it attaches to the shower pan surface.

Make a hole in the middle of the backer board in the same spot where you marked the hole. Use a screwdriver or PVC pipe cutter to make drilling this hole easier.

  • Use a hammer and nail to secure both ends of the backer board. Clean any residue and fasteners from the shower pan with a damp cloth.

Allow the backer board to set for eight hours before installing tile or other materials, and do not stand directly on it until it fully cures.

How Far Up The Wall Should I Place A Shower Pan Liner?

Atleast 6 inches above the framed or (roughed-in) curb height

When choosing a shower pan liner, it is important to know the height of your curb.

If your curb height is, for example, 54 inches, then the minimum length of a shower pan liner would be 54 inches, and the maximum length of a shower pan liner would be 71 inches.

If your final curb height is 54 inches and you need a shower pan liner, then the minimum length of a shower pan liner would be 54 inches.

However, it’s important to know that the shower pan liner will drop another 6 inches once installed.

And because you have a final curb height of 54 inches, you need at least 4 more inches for the shower pan liner to drop; therefore, you need a 62-inch shower pan liner.

A minimum of 2 inches above the framed or (roughed-in) final height

It is important to know that the shower pan liner will drop another 6 inches once installed, and because you have a final curb height of 54 inches.

You only need 2 more inches for the shower pan liner to drop. Therefore, you need a 60-inch shower pan liner.

Should Backer Board Touch Shower Pan?

Do I Have To Tape Cement Board Before Tiling?

Yes. If you’re going to tile, it’s generally easier to do so when you lay the tiles down first and then cover them with a layer of cement board.

Make sure the cement board is smooth and has no bumps or ridges on the surface before you start tiling.

This will help your tiling project by cutting down on excess dust between the tiles. It will also help your tiles stay in place and reduce the chance of any problems with cracking or breakage later.

The problem with most adhesives is that they will leave a residue on whatever surface you apply the tiles to.

For example, if you apply adhesive directly to your subfloor, what would happen when you put your tile on top?

It would create tiny bumps and ridges between each tile, and these bumps can often become even more prominent if moisture comes later.

For example, if water seeps in between the tiles, the cement board will be slightly expanded, which you won’t find on a smooth finish.

This is most noticeable when looking at many kitchens and bathrooms tiled over existing linoleum and vinyl.

Often these surfaces will have a bunch of divots and bumps where the flooring tried to push its way up out of the floor or broke through the tile material itself.

A smooth finish is important to a good tiling project, so installing your cement board before you start tiling is the best thing you can do.

Before laying down, the tiles spread a thin layer of mortar between the joints in your subfloor and then float it on top of the existing flooring.

After laying down a base layer of cement board, use spacers to allow for a slight gap between each tile. Then apply your tiles with an adhesive to get that smooth finish I just talked about.

Does The Backer Board Need Sealing?

Yes. Most backer board needs sealing, but it depends on your use. If your backer board will be on the interior side of a wall, or if you plan to paint the surface of your backer board, it does not need sealing.

However, if moisture or water vapor is exposed, you need to seal the surface with a membrane-like Drylok before installing it.

(Note: Drywall is like a membrane, but you don’t need to seal it.) If you’re using a backer board in a bathroom, bedroom, or other areas you will never paint, seal it.

That’s the right thing to do with a backer board. It won’t hurt the board and will help prevent mold, mildew, and water damage.

Understanding the different kinds of backer boards can be helpful when deciding whether to sell them. One backer board (like Hardibacker) has a paper layer on both sides.

This paper is like drywall in that it’s gypsum-based and acts as a vapor barrier. It is a very thin layer of paper that you don’t need to seal.

Two types of backer boards (like LVL) do not have any paper on the surface. They are more wood-based and have a similar feel to plywood.

They also don’t need sealing because they lack the paper-based vapor barrier found in other materials and are more about waterproofing than vapor prevention.

Does The Green Board Go Behind The Shower Pan?

Yes. A thin membrane gets behind the shower pan and covers the entire floor. It’s not always possible to see it, but it’s there.

The membrane will catch any water leaking from the shower and prevent it from seeping into the wall.

It’s essential to use a quality product when installing these membranes because they are not waterproof.

If your flooring is waterproof and you plan to install ceramic tile, you won’t need one.

Here are some of the more popular waterproofing membranes we use in our showers:

Kerdi: Kerdi waterproofing membrane is an innovative product perfect for the shower.

It doesn’t rely on water wicking away from the tiles like other products, so you can install it over almost any substrate. Kerdi speaks for itself.

Green board: Probably the most common membrane. A Green board is a brilliant choice when you have to get creative with your shower.

This product comes in 4 different widths, and you can install it at any height. It’s easy to work with and non-adhesive, so it won’t stick to your shower tiles.

It’s available in different colors if you want to match your tile.

Tile backer board: not as common in showers, but it is a good option when you want a waterproof backing for your tile. The tighter weave makes it better than other options.

It doesn’t have the same adhesive properties as other membranes, so you’ll need to screw it down before installing the tile.

How Do You Waterproof Drywall In A Shower?

You can waterproof drywall in a shower with the following steps:

  1. First, seal the seams of your wet room with a marine-grade paintable waterproofing membrane approved for interior and exterior use.
  2. Next, install sturdy tape to all seams and other areas that might be prone to getting wet, like around taps or pipes.
  3. Use an industrial trowel or rake (can also use spray adhesive) to put a silicone layer over your taped seams.
  4. Use a plastic-beaded roller to roll on an additional bead of silicone over the tape.
  5. After that, spray a layer of water-based patching compound on both sides of each seam.

You can also use a thick coat of mort-locking compound to fasten the walls together or put a layer of tape between them and all other seams, especially if they get exposed to the elements.

Finally, paint all the surfaces on both sides of the walls with waterproof wall paint.

Painted with more than one coat, you can apply a layer of water sealant to your drywall because this will also result in an extra waterproof barrier between your drywall and the rest of the wet room area.

Fixing A Gap Between Shower Walls?

You can fix a gap between shower walls by using caulk. The steps to do this are:

-Apply caulk to the seam of the two tiles, making sure not to get too close to the tile that is currently in use

-Press firmly on the tile with your hand, and then wipe away any excess caulk with a damp cloth

-Wait until dry before using the shower again.

If you don’t want to use caulk because you have tiled walls, try using Flexi Duct Tape. This tape will hold water and steam, so your shower isn’t constantly wet from condensation.

The tape has a pressure-sensitive adhesive; you can cut it to any length.

Another way is to use a gap filler. You’ll find these sold in most hardware stores and are easy to use. They can fill gaps up to 1/8″ in width. For the best results, apply the gap filler before tiling.

When you’re tiling your shower, be kind to the walls. Use a push broom to sweep before you begin, and try to keep things as level as possible for a nice finish.

What Kind Of Thin-Set Goes Under The Cement Board?

Thin set-mortar is an adhesive for installing ceramic, stone, and porcelain tile. It usually gets applied to a surface of the backer board or plywood before setting the tiles.

And while there are many different thin-set mortars available, you can use only one with cement board: cement board thin-set mortar.

The first step in any tiling project is determining which type of thin-set mortar you need to use on your chosen substrate (cement board).

Some thin-set mortar products have labels specifically for cement board use, and others do not.

If you want to use a product labeled specifically for cement board, use it over a surface attached to the cement board substrate with concrete screws.

To use a non-cement board product over your cement board, you must first attach the substrate before applying thin-set mortar.

Remove the backing from the thin-set mortar product. Create a generous bead of thin-set mortar over the surface.

Place the backer board in place and center it over the thin-set mortar; use a pencil to help you make sure that it’s level with each end.

Hold another sheet of plywood in position and then secure it with nails: this will help ensure that your cement board is level and plumb, thus eliminating two later steps.

Use a trowel to spread the thin-set mortar over the surface of the backer board; make sure not to leave any gaps between adjoining pieces.

Remove the protective covering from the face of the backer board. Gently slide chunks of tile into place and use spacers to assist you with spacing them evenly.

Use a damp sponge to clean off gently excess thin-set mortar from around the edges while leaving it in your grouted joints. This will help produce proper spacing between tiles.

Use a notched trowel to spread thin-set-mortar over your grout joints, and then install the tile using spacers.

Clean the surface of your tiles, then allow the thin-set mortar to set up for 30 minutes before grouting it.

Allow the thin-set-mortar to set up completely (24 hours) before installing any heavier tile than 8 pounds per square foot.

Do I Have To Tape Seams On Hardibacker?

Yes. It’s that important, so ensure you have some before diving into any projects. If the seams are visible, there will be voids in your Hardibacker flooring.

Hardibacker, also known as HardiPlank®, is a resilient paving material that you can glue down or nail down to the subfloor.

You can use it as a durable flooring alternative to concrete and tiles.

The seams will be visible when you don’t use tape around your tiles when you have tiled floors.

Taping seams on Hardibacker before laying it assures the covering of those seams, so no unwanted voids are present in your flooring.

There are a few different ways to tap seams on Hardibacker, but you can use a combination of all of them to get the job done.

  • Taping with Titebond II: This adhesive is strong and will give you a stronger bond and protect against moisture and mechanical damage.
  • It also boasts usage as a sealant for your Hardibacker before moving it into place or for taping seams together when making DIY floor panels and tiles.
  • Taping with DAP Kwik Seal Seam Sealer: This adhesive is another great option for sealing seams on your Hardibacker floor.

It’s a heavy-duty sealer that will keep moisture from penetrating the seams and protect your flooring even more than if you use only Titebond II.

  • Sealing with Zinsser B-I-N: If you have ever used this product for painting, you will be familiar with how it works.

It comes in a spray and will fill any gaps between the seams of your Hardibacker, which will make them look seamless when finished. This product is also water-resistant when dry.

  • Sealing with Acrylic Latex Floor Paint: Another option is to put paint on your seams to seal them.

While this will not be as reliable as the other options, it is a convenient way to conceal seams in your Hardibacker.

Does The Backer Board Go Over Drywall?

Yes. That’s because a layer of gypsum-based, fireproof drywall is applied to the gypsum cheeseboard’s interior side to build a wall section – or an upgrade to – insulated concrete form (ICF) construction.

So, you can take the fireproof drywall and stick it over what you’ve got.

The Fire Code in many jurisdictions allows for this – but not necessarily the building code.

Most building codes call for a layer of gypsum board over the top of whatever the thermal barrier is – if one is a requirement at all.

So, if you’re targeting an older structure, your drywall over backer board assembly will meet most requirements.

But if you’re building new construction and want to use the assembly, it may not be necessary for your jurisdiction.

Probably a good idea to check before you start building. So, let’s have a look at the assembly.

In this case, the backer board has a vertical orientation along the long edge of the wall section so that it serves as a thermal break between air flows (downward) and heat sources (upward).

The purpose of the drywall by itself, with the indoor side facing upward, is to protect against radiant heat.

The gypsum board comprises a special manufacturing process protecting against direct flame impact and fire. I call this a “thermal barrier.”

You can apply a thermal barrier on top of an exterior layer of fire- and water-resistant “Class A” gypsum board.

But note that class A gypsum board is fire resistant but not fireproof.

Do You Have To Waterproof The Cement Board?

No. The Cement board, unlike regular drywall, is a closed surface. This means that water cannot penetrate the surface.

So long as you’re using a cement board in an area where there is no chance of water spilling on it or coming into contact, you don’t have to waterproof it before installing it.

If you are using a cement board in an area with a high chance of water coming into contact, it’s a good idea to waterproof it.

The way you waterproof cement board depends on what type of cement board you’re using.

If you’re using a regular cement board, or if your cement board has a regular paper surface on it, follow the instructions that come with the cement board.

Put a liquid waterproofing agent on the cement board to waterproof a cement board. Using a cement board with a paper surface makes waterproofing very easy.

There are different types of liquid waterproofing agents. Some boards have special sealers that make the cement board even more water-resistant.

If the sealer is on the board, there is no need for any additional steps, and it’s ready for use with no further preparation or treatment required beforehand.

Once the sealer application to the cement board is complete, it becomes waterproof.

Another liquid waterproofing agent is a water-based primer that you can buy at home improvement stores.

This type of liquid waterproofing agent is easy to apply and will turn your cement board into an impervious area to water.


The construction of shower pans is usually from cement-based materials for their strength. Any holes in the shower pan will cause leaks, costing you an absolute fortune to repair.

If you are very careful about where and how the holes come from, you can easily seal any leaks inside your shower pan with a patch kit, removing the need for expert plumbing services.


Hi! I' am Tom. I was a manager in one of the biggest stores for over 10 Years, am also an SEO by night. I don't like to call myself a blogger; they are very analytical, do email marketing, and know all SEO stuff. I faced many questions from customers about different products, and there was hardly any help on the internet. After learning all the things about these products as a manager the hard way, I decided to start a blog and help other people.

Recent Posts