Kerdi Board vs. Drywall: Which to Choose?

Kerdi Board vs. Drywall: Which to Choose?

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If you are planning on building a new home or renovating an old one, you’ll obviously need to have floors and walls. Now, as far as those things are concerned, there are many materials for you to choose from.

Two common building materials you may be familiar with are Kerdi Board and Drywall. Now, these are two very different things and they certainly don’t serve the same puporses either. Let’s figure out what both of these materials are, what makes them different from each other, and which to use in specific cases.

Kerdi Board and Drywall: The Basics

Before we start talking about similarities and differences, let’s first figure out what both Kerdi Board and drywall are.

What Is Kerdi Board?

First, we have Kerdi Board, which is a special type of extruded polystyrene foam panel, very similar to Styrofoam. These foam panels feature a reinforcement material on both face sides and also feature fleece webbing, which allows them to be easily anchored in Thinset mortar.

These foam panels are very lightweight, totally waterproof, and surprisingly durable for what they are. These Kerdi Boards are used as building panels, particularly as a multifunctional tile substrate, or in other words, to underlay tile, mainly in bathrooms and kitchens.

Kerdi Board allows you to easily attach tiles to it, while also producing a waterproof barrier between the tiles and the walls or floors underneath. That said, this material does not look nice and it’s not something you would every use for any kind of visible wall or floor. This is an underlayment material.

What Is Drywall?

We then have drywall, which is a very common and popular building material, which can also be referred to as wallboard, plasterboard, custard board, gypsum panel, and sheet rock.

This is a special type of panel that is made out of calcium sulfate dihydrate, often with some additives. In other words, this is a gypsum panel, with that gypsum slurry being pumped into a flat sheet and laid in between sheets of backer and facer paper.

Simply put, drywall is a somewhat thick layer of plaster squeezed in between two sheets of special paper. Drywall is most often used for the building of interior walls and ceilings, as it is fairly cost-effective and also quite easy to work with, plus it looks decent and is easy to sand and paint.

Now, do keep in mind that drywall, although it looks nice and is somewhat easy to work with, is not very durable, particularly in terms of impact resistant. It also can’t bear any weight, and due to it not being water resistant, it also should not be used outdoors.

Similarities of Kerdi Board and Drywall

Okay, so funny enough, this is our first article where we can’t find a single similarity between the two things being compared. Besides both Kerdi Board and drywall being common building materials, they don’t actually share anything in common at all. They are 100% totally different things.

So, that said, let’s move on to the next section.

Differences Between Kerdi Board and Drywall

Now that we know what Kerdi Board and drywall are, let’s figure out what makes them different from each other.

1. The Material

The first major difference here is that drywall is made out of calcium sulfate. It’s a gypsum panel sandwiched in between papers. Kerdi Board, on the other hand, is made out of extruded foam, more or less a special type of Styrofoam. These are just two totally different things.

2. The Application

The application or uses of both materials is also vastly different. Drywall is used to make finished interior walls and ceilings, ones that are visible. They can be sanded and painted with ease, and make for a popular walling material. Kerdi Board, on the other hand, is used as a backer or substrate for tile, mainly in bathrooms and kitchens. You’d never be able to visibly see this material in a home, as it’s always going to be under tiles.

3. Weight and Ease of Installation

Something else worth mentioning is that Kerdi Board is much easier to install than drywall. Drywall is very heavy, and you will likely need two or more people to install it, plus it also requires special hardware to install. Kerdi Board, because it is made of foam, is many times lighter than a piece of drywall of the same size. It can be handled and installed by a single person and doesn’t require special mounting hardware.

4. Durability

Okay, so to be clear, neither of these materials are durable per se, although drywall is even weaker than Kerdi Board. Kerdi Board can actually handle a bit of impact and is slightly flexible, both of which are not true of drywall. You could step on or punch a piece of drywall and it will crumble.

5. Water Resistance

Drywall is not waterproof or really even water resistant, which is why it’s not used for floor or for outdoor purposes. Kerdi Board is waterproof, which is why it is used as a backer for tile in bathrooms and kitchens.

Kerdi Board vs. Drywall: Which Should You Use?

If you are making interior walls, then drywall is what you need to use.

If you are underlaying tiles, then Kerdi Board – or one of its alternatives – is what you would want.


As you can see, drywall and Kerdi Board are two totally different things and are not at all suitable for the same purposes.

How Does Drywall Compare with Other Materials?

You might also be interested in seeing how drywall compares with: