Is Grout Waterproof?

By Ben Victor

Updated: 8th August 2023

Grout is a fantastic material that is ultimately used to fill the gaps between tiles. Naturally, being typically used for bathroom tiles, it is not surprising to wonder: is grout waterproof?

In this short guide, we will explore this question as well as provide an answer, and suitable recommendations. Let’s get into it!

So… Is Grout Waterproof?

The quick answer to this question is no it is not! Grout itself is a porous material, meaning it has minute holes that water (and air) can pass through and be absorbed.

In order to answer this question properly, we need to first understand what exactly waterproof means.

What does Waterproof Grout mean?

Waterproof itself means “impervious to water”. In simple terms, this means that it does not allow water to go through.

Grout is described as a porous (has tiny holes) material, typically used to seal joints between tiles and therefore by definition is not waterproof.

For most grout, especially bathroom or shower grout, you will need to “seal” these holes with grout sealer. Grout sealer is usually a clear, water-based, liquid that fills the pores between the grout, to preserve it as well as make it water-repellant – but not waterproof.

Related: What is grout sealer?

Do I need grout sealer?

This all depends on what type of material you used for your tiles lines. Although the name used to describe tile lines is grout, quite often grout is not the material that has been used. Also, if you used a grout pen, some of them are similar to grout sealers in that they make the grout water resistant.

There are a number of different products or materials as grout, these include:

Grout
Caulk
Sealant
Epoxy
Cement

Grout and sealant are quite commonly used for grouting. Sealant itself is quite a popular choice in a shower because it is usually waterproof and has a whole heap of other features, that make it more favourable than grout.

Related: Best Shower Sealant

Which types of grout are waterproof?

Below is a table that outlines which types of grout are waterproof and which are not:

Related: How to seal grout in a shower

What is the difference between waterproof and water-resistant?

As discussed earlier, waterproof essentially means not allowing water in. Water-resistant on the other hand means the water is able to penetrate to some degree but not totally.

Grout sealer and grout pens are great for preserving grout, making it look newer and also making it water resistant. Because of its nature, you would need to keep reapplying it every so often to renew the water-resistance effect.

Ultimately, if you apply lots of coats to your grout, water protection will be much greater but you still cannot guarantee that it will become waterproof.