How Many Screws Per Kerdi Board?

A Kerdi-Board is a great product to use if you want to DIY the waterproofing installation in the bathroom. While it is easy to install on your own, one of the most common questions is how many screws a Kerdi-Board will need to be properly secure. We were curious about this, so we researched this topic to find the answers for you.

Kerdi-Board panels come in different sizes, depending on the area that you will be working with. Typically, most users get the standard 48" x 32" panels, which you'll also get from a Kerdi-Board kit. A panel of this size usually uses about 10 to 20 screws to secure the boards properly, but the number of screws will depend on the size of the board you are using.

Installing a Kerdi-Board can be a quick and easy project you can do within the day. This post will discuss how to install a Kerdi-Board properly and what other products you can use to waterproof the bathroom. Keep reading as we learn more about using the Kerdi-Board, and we hope you enjoy this post!

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How Many Screws Per Kerdi Board?

Waterproofing the fixtures in the bathroom is necessary to prevent damage when the floors and walls get wet. Areas that surround the shower and the tub should have excellent moisture protection. One of the best products for this job is the Schluter Kerdi-Board.

The Schluter Kerdi-Board is a waterproof and vapor-retardant board used as a tile substrate. These boards are made of extruded polystyrene foam, with the sides covered in fleece webbing and special reinforcement material. The sides are made to help anchor thin-set mortar for tile applications.

You'll find various sizes and thicknesses available if you want to use Kerdi-Board panels for your bathroom. These boards typically come in widths of 48" and lengths of 32", 64", 96", and 120". If these boards are too big to use in the space you are working on, you can easily cut them to size, so it fits the area.

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Generally, most people use the 48" x 32" Kerdi-Board in their bathrooms. This is also close to the size you will get if you purchase the Kerdi-Board kit, which can cover up to 101 square feet of wall area. These panels are the perfect size to use in a single shower or tub area, and they are easy to handle with this size.

For a 48" x 32" Kerdi-Board, you'll need to use about 10 to 20 screws per board. This is because a Kerdi-Board panel has a maximum allowable on-center spacing for fasteners. Vertically, you can space your fasteners with a maximum of 12". Horizontally, the spacers should be fastened to the studs on the wall, with a maximum distance of 16".

Check out this set of screws and washers on Amazon.

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Bigger sizes of Kerdi Boards will require more screws and washers to fasten them to the wall securely. Extra screws and washers can be purchased separately in packs of 40s and 100s.

How To Install A Kerdi-Board

One of the best things about the Kerdi Board is how easy it is to install. Depending on the size of your shower or tub, you can install Kerdi Boards in a day. Sometimes, it can only take a few hours if you have everything ready and set up during installation. 

The quickest and easiest way to work with Kerdi-Boards is using their pre-made Kerdi-Board kits. These kits can be used in spaces up to 101 square feet of wall area and have everything you may need for installation. It comes with Kerdi-Board panels, screws, washers, waterproofing strips and seals, and sealants.

Get this Kerdi-Board Kit on Amazon.

This video will show you how to easily attach and install a Kerdi-Board to your bathroom shower or tub walls.

Materials Needed:

  • Kerdi-Board Kit
  • Unmodified thin-set mortar
  • Utility knife
  • Straight edge ruler
  • Notched trowel
  • Margin trowel
  • Caulking gun
  • Painter's tape
  • Impact driver
  • Impact driver drill/screwdriver bits
  • 5-gallon bucket
  • Rags


  1. Start by getting a Kerdi-Board kit and check if it has all the things that you will need. It should include a set of 8 panels, a roll of Kerdi-Band, Kerdi-Seals for the pipes and the mixing valve, screws and washers, and the Kerdi-Fix compound.
  2. Determine the layout of the Kerdi-Boards on your walls. This will depend on the size of the wall you will be installing into. Kerdi-Boards can be installed either vertically or horizontally. Take note that the vertical edges of the Kerdi-Board panel must be positioned over the center of the stud or solid backing.
  3. Measure the area you need to cover with the Kerdi-Board. Cut the panels according to size if you need them to be smaller. Use a utility knife to cut the boards quickly. Measure the openings for the pipe protrusions and the mixing valve, and cut the holes on the board.
  4. Screw the Kerdi-Board on the stud using the included screws and washers. You can place the screws between adjacent panels so the washer can fasten two panels simultaneously. The maximum allowable spacing for the fasteners is 12" vertically and 16" horizontally.
  5. Remove the protective film from the bathtub. Place painter's tape around the entirety of the tub deck for protection. Ensure that the tape adheres closely to the lip of the tub but not directly underneath the Kerdi-Board. 
  6. Using a caulking gun, load the Kerdi-Fix seal. Caulk the space between the Kerdi-Boards and the tub, and spread it using a small notched trowel. 
  7. With a Kerdi Trowel or a V-notched trowel, apply 5 inches of thin-set mortar to the Kerdi-Board. Remember to comb additional mortar to the area where the Kerdi-Band will be installed.
  8. Cut the Kerdi-Band to size and apply it to the mortar and the Kerdi-Fix to ensure it covers all the spaces. There should be a 2-inch overlap on all the seams. Flatten the membrane using a margin trowel. 
  9. Immediately remove the painter's tape after the application.
  10. Cover all the seams, joints, corners, and fastener penetrations with thin-set mortar and Kerdi-Band. Use the Kerdi-Seals over the pipe protrusions and the mixing valves.
  11. Use additional Kerdi-Band on the edges to make a clean finish on the tub or shower. The Kerdi-Board installation is complete, and you can tile the space accordingly. 

Are There Other Kerdi Board Products To Use?

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Aside from the Kerdi-Board, Schluter offers other products to help waterproof your bathrooms. To make it easier for many homeowners, Schluter has created a line of pre-fabricated substrates that are easy to use and install. They work similarly to the Kerdi-Board, and they fit together seamlessly.

One of the benefits of using Kerdi-Board products is the ease of installation and how they integrate well with each other. These Kerdi products bond easily to the boards, and they are all waterproofed, so it cuts down the work that needs to be done.

Here are some of the best Kerdi products you can use for your shower or tub area in the bathroom:

Shower niche

See this Kerdi-Board shower niche on Amazon.

Before Kerdi-Boards, installing waterproofing panels on bathroom walls was hard. Adding a niche to the shower wall is additional work, and cutting the panels to the niche's size takes time. Fortunately, Schluter created a pre-fabricated shower niche that you can easily install by cutting a hole through the Kerdi-Board.

Shower bench

Check out this Kerdi-Board shower bench on Amazon.

If you plan to add a shower bench to your bathroom, you can easily do it with a pre-fabricated shower bench from Schluter. These benches already come pre-measured and ready to install. All you need is some bonding compound and waterproofing corners to install the shower bench in place. 

Shower trays

Get the Kerdi-Board shower tray on Amazon.

These pre-fabricated shower trays eliminate the need for a mortar bed and make shower installation easy. Kerdi-Board sloped shower trays come in different sizes, perfect for any size shower you want in your home. These trays can be installed seamlessly with other Kerdi products for a complete waterproof system for your shower or tub. 

Final Thoughts

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Making sure that the fixtures in the bathroom have good moisture prevention can now be easily done with Kerdi-Boards. Because they come in a kit, these boards are easy to install, and you don't have to worry about messing them up. Follow the instructions on the kit, and your bathroom is now on its way to being waterproofed for life. 

Would you like to know more about other options you can use for your bathroom walls and floors? We have a few articles that might interest you:

Built-In Vs. Floating Shower Bench: Pros And Cons

Kerdi Board Vs. Cement Board: Uses, Differences, & Considerations For Your Project

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