What Do You Put Under A Shower Base?

For experienced do-it-yourselfers, a bathroom can be a big but rewarding renovation. If you have an old shower pan or are looking to change the room's style, there are a few procedures to make sure everything stays in place. While newer homes might not have any building restrictions, older historic homes may require some city permits to get started. Next, you'll need to know what to put under a shower base. We've researched this to find the answer for you.

In order to install a new shower, you'll need to carefully remove the old pan by removing the studs and drain ring. Then you'll be able to tack a new waterproof liner onto the subfloor, cover the liner in mortar, insert the pan, and put the final touches on when it dries. The process of putting in a new shower pan and base can take a day or two, so make sure you leave yourself enough time and have another method of showering ready!

All in all, there are a handful of steps to follow when it comes to replacing or adding a shower pan. By reading this article ahead of time, you'll save yourself the back-and-forth trips to the store and be able to add a new renovation skill under your belt! Below are the general steps for putting in a shower base and pan, and of course, if your shower pan comes with specific manufacturer instructions, follow those. 

Interior of a modern bathroom with contemporary interior design, What Do You Put Under A Shower Base?

What's the difference between shower base and shower pan?

While these two terms are often interchangeable, it is crucial to know the difference. Having this vocabulary under your belt will help you understand any lingo being used by contractors or hardware store employees. 

Difference betwenn Shower base and a shower pan, What Do You Put Under A Shower Base?

Shower Base

A shower base is a structural base underneath the shower pan. This typically references the layer of mortar and liner sitting on top of your subfloor, beneath the shower pan. Having a liner or sealant put down before the mortar will ensure your subfloor doesn't get wet.

Shower drain box grate on a shower base

Shower Pan

A shower pan is an acrylic, fiberglass, or tiled aluminum pan that sits on top of the shower base, in other words, your shower floor. Pans come in two applications. The first is ready to use; just install and done. The second is a pan that can be tiled over. If you're looking to match an existing tile or add some spice to the floor, this is the option for you.

Shower Pan measure the level of placement

When looking for a shower pan that you can tile, make sure it is specified in the product description. Aluminum and polyurethane pans are the most common to be tiled. Acrylic, however, cannot be tiled. 

Click here to view this acrylic shower pan on Amazon.

Steps to Install a New Shower Base

A plumbing plan of a house with PVC pipes and a measuring tape on top of a floor plan

  1. Tack a waterproof pan liner down: after removing your old pan, make sure there is a clean, dust-free subsurface to begin your new project.
  2. Dry fit the new pan and make sure it's level: for this step, it's best to have two levelers to place on each side of the pan. If one side is lower, add shims until the pan levels out and tack those in place.
  3. Using a special type of putty called plumbers putty, secure your new drain in place to the pan. 
  4. The mortar you have mixed should be a peanut butter consistency; apply about an inch think layer to the liner, avoiding the drain hole. 
  5. Place new plan into the mortar.
  6. Mortar can expand when drying; it is recommended to add temporary strapping to hold it in place.
  7. Allow the mortar to dry for about a day.

Click here to view this pan liner on Amazon.

Mortar Options 

Mortar mixes come in four different types. These types are categorized by their component ratio makeup of sand, lime, and cement. Based on how much or how little a mix of mortar has will change the characteristics of durability and bond strength, flexibility when settling, and moisture resistance. If you buy a shower pan kit, it could come with its own mortar mix and will save you a second trip to the store!

Type N

The best general-purpose mortar type. Type N can be used on interior and exterior surfaces and for load-bearing walls due to its severe weather resistance, flexibility, and strength. This mortar grade is made by combining one part cement, one part lime, and six parts sand. 

Type M

The highest strength type of mortar, Type M, is most commonly used to build foundations or retaining walls. Type M can hold the highest pressure level, is made up of three parts cement, one part lime, and twelve parts sand.

Type S

Similar to Type N, this type of mortar is medium strength. The main difference is that Type S mortar is best used for outdoor projects that could get wet. For example, an outside patio or non-load-bearing exterior walls. Type S is created by mixing two parts cement, one part lime, and nine parts sand.

Type O

The lowest strength mortar type. Type O is not the first choice for sturdy base settings. Instead, use Type O to fix any cracks in the previously laid mortar. Due to its limited strength, it is an interior-only type of mortar. This mortar is formed of one part cement, two-part lime, and nine-parts sand.

A man using a trowel to scoop tile adhesive

Can you use a thin-set for a shower base?

This type of mortar has been specifically modified to use for adhering tile to walls or shower pans. Thin-set is a form of mortar with latex and polymer additives to increase the bonding strength to surfaces. It would not be recommended to use thin-set as your bonding agent for the shower pan to the subfloor. 

Do you need mortar under a fiberglass shower pan?

Mortar is recommended to use under all shower pans. Mortar reduces the risk of your pan slipping or cracking from an uneven surface. Fiberglass-infused shower pans are very durable and can last for years. These types of pans often have a high-gloss finish, so if you're in an environment that needs a better grip on the floor, look for one that is tile compatible. 

Do you tile under a shower base?

It is best practice for the shower base to mortar under your pan instead of laying it straight on the tile. By removing the previous tile and setting the pan into the mortar, you reduce the risk of mold. The underside of the shower pan is not flat but instead has grooves and pockets. If the pan was to be laid directly onto the tile, there is more space for moisture to get caught. More moisture means more mold. 

Not to worry though, you can always tile on top of an approved shower pan. There's no need to have a plain white or tan shower floor. By using a pan made for tiling, you can add the perfect tile style to fit your personality.

Tiling a shower pan

When you have your tile-approved pan and tile of choice, it's time for the final touch of tiling the pan's surface. For this process, you'll be using the thin-set that was mentioned above. Pans should be dry and clean before beginning. Cover your drain to reduce the risk of tiling over it. Then start by dry-fitting your tile. Dry-fitting is an important step so you don't waste extra materials and money. Remember to measure twice and cut once! Having correct measurements will help keep track of how many tiles and thin-set you'll need for the pan. If you have a shower pan that is not square or rectangular, a wet saw will be a necessary tool for those odd corners. 

Click here to view these hexagon shower tiles on Amazon.

That's a wrap!

The bathroom is a hub of activity, so why not make it easy on the eyes too! Whether you're looking to change out the tub for a shower or update your old shower pan, it isn't as quick as changing the shower curtain. Installing a shower base and pan will take around a day or two, a perfect weekend project with the right amount of dedication. Having an even and clean base will be crucial for the longevity of your shower pan. The shower base is the structural standing on which you will place the shower pan on. Coming in neutral colors or having tile compatibility means that there's a shower pan out there for everyone! 

Now that your shower is complete, check out these articles for more design insight:

40+ Boho Bathroom Ideas [With Pictures!]

15 Unique Abstract Shower Curtains You Should Check Out

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