Grout vs Silicone: What's Best When Renovating Your Bathroom?

You want to ensure that you have the safest, most secure bathroom possible. Sealing up all the little gaps of the joints, such as between the shower tray and the floor, or between the bath and the tiles, is a very important part of that.

Otherwise, the little cracks are a haven for moisture, leading water to seep beneath the surface where it can cause all sorts of trouble, including damp, mould, flooding, and even damage under the frame of the bath.

The constant presence of water, steam, and condensation can do a lot of damage if you’re not protected from it. To ensure the most even, tightly bonded seal, you need the right materials.

Silicone and grout are the two most widely used substances, but how do they compare? Here, we’re going to look at the pros, the cons, and which you want to use in each situation.

What is grout?

First of all, you need a good idea of what each substance actually is. Grout is a composite, a mix made of water, cement, sand, and a colour tint.

The bulkier varieties used to fill bigger gaps also often contain fine gravel. It’s applied as a paste before it hardens over time as it dries. When using a grout in the bathroom, you want to make sure that it also contains latex, as this is what gives it its waterproof property.

Even still, the material is more porous, so you might want to apply a grout sealing agent on top of it to stop the growth of any mould. The biggest noticeable difference between silicone and grout is that the former is more flexible, while the latter is harder and more rigid.

What is silicone?

The much more flexible silicone, which is also commonly referred to as caulk, is water and airtight without the need for any extra sealant. Of course, this is only with effect application.

Using it without the right step-by-step process can result in an uneven application that has room for water to seep beneath.

As the name suggests, it’s made of silicon, mixed with oxygen and sometimes a few other elements like carbon and hydrogen. It’s not a paste like grout, but it comes out as a liquid. This can make it much harder to apply than grout, and if you’re using it for the first time, it’s wise to do so with the help of a well-written step-by-step guide.

It’s applied as a liquid, then it dries into a flexible, but tightly-bonded rubber-like plastic.

Grout – Pros and cons

The first majorly noticeable advantage that grout has over silicone is how easy it is to use. Because of its paste-like form, it’s easier to get to fit into tighter spaces and easy to wipe away any excess to ensure an even fill.

A waterproof grout costs more than a purely cement based one, but it is stain resistant, ensures an even colour, and is mostly impervious to water. A grout sealing agent can be used as an added level of security, too.

The main problem with grout is the fact that it’s somewhat brittle. Under pressure, it will start to form hairline cracks which can cause water to seep through anyway. Beyond that, it’s a little more porous than silicone, even the waterproof forms.

Grout – When you should use it

Because grout does not withstand pressure well, it is not well suited for sealing the joints of the bath, sink or the shower tray. By this, we mean the corners where the material meets the wall.

Baths, sinks, and shower trays shift ever so slightly when weight is applied to them. This shift will cause the grout to crack, which becomes a pathway for water to leak through.

However, when it comes to applying an even seal on any materials that are on the same plane, it works just fine. This includes wall tiles, for instance.

Silicone – Pros and cons

Silicone’s greatest advantage is how flexible it is. Not only does this mean that it can fit into a lot of awkward spaces and remain airtight but it also means that it keeps that strong bonded fit when the surface moves.

For instance, baths shift ever so slightly with the weight of water or a person’s body pressing down on them. Silicone will remain firmly bonded to the material even then. What’s more, it’s entirely watertight so long as the application process went smoothly.

The biggest downside of silicone, however, is that it is a lot harder to apply properly than grout. If you get it wrong or you don’t take the time to smooth the line, silicone will dry with little gaps that water can seep under directly. This means you should be careful with it and ensure that you’re following a step-by-step guide if you’ve never used it before.

Most sealants are white, too, and cannot be painted after they have been applied. You also have to ensure you’re getting one suited to the materials you’re using in the bathroom, as well as one with antifungal properties just to make sure that mould doesn’t start growing on it over time.

Silicone – When you should use it

As mentioned, silicone works well in places where shifts in pressure can cause your grout to crack. For most bathrooms, this means using it as a sealant for the joints of the shower tray and the bath.

Anywhere that you need a flexible, watertight sealant between two objects on a different plane, silicone is your best bet.

How to apply grout

Grout is mostly used to seal the cracks between tiles on a bathroom wall. In this case, you have to ensure you’ve given enough time for the tile adhesive to fully dry, or else it can mix with the grout and the effectiveness of both will be compromised.

Grout dries much more quickly than silicone, so you want to work with smaller spaces at a time, rather than one big space. This gives you time to even and adjust the grout before it fully dries.

Grout is easy to use. With a rubber grout float, all you have to do is scoop up the mix on one end (don’t cover the whole float). Working from the bottom up, apply the grout to the tile diagonally using the edge to force the mix into the gaps between the tiles.

Once you have the gaps filled, then you use the edge of the float again, this time to scrape any residue off the faces of the tiles. As you go, ensure you’re scraping any residue from the float, too. Clean it often or it can start hardening on the float which will mess up your applications.

After twenty minutes, all you have to do is sponge the grout residue from the tiles and cracks with a bucket of clean, warm water and make sure the grout is even applied and bonding by pressing in with your finger of a tool. Clean the tile surface once more and you’re done.

How to apply silicone

Applying silicone in the bathroom requires a lot of prep-work. If, for instance, you are replacing an older sealant, you have to ensure that it’s fully removed. Old silicone can be sliced away easily enough with a sharp knife, like a Stanley knife.

Then you have to fully clean the joint that you’re sealing. Warm-soapy water can be used to clean away grease, dirt, and dust. Then you have to leave it to fully dry. Skip this step, and the silicone will have trouble sealing onto the material.

The process of actually applying silicone can be messy if you’re not careful too. Most bathroom owners want to ensure that they have a clean, even line of consistent thickness all the way from one end to the other.

Read the instructions on your silicone sealant tube carefully and a hole in the nozzle as directed before loading it into a gun. You might want to use masking tape on either side of the joint, above and below, leaving about 3mm of distance from the centre. Then, you apply the sealant.

You want to use it in as consistent and smooth a motion as possible, without stopping until you reach the end. With just a little pressure, smooth the sealant so that it bonds to the surface. Then you pull back the masking tape and any excess sealant with it, leaving a nice, even line.

Note, you have to do this before the sealant dries. Otherwise, you will just have masking tape stuck under a plastic seal. Once you’re all done, it takes 24 hours for silicone to fully dry.

In conclusion

Both grout and silicone have their place in the bathroom. Otherwise, you wouldn’t have both on the market.

Knowing when to use it is all about knowing the strengths and weaknesses of each material and how they react with other materials, too.

In general, grout is a great option for shower tiles but if you’re sealing the joint of a bath or a shower tray, you need the flexibility and the anti-fungal properties of a good watertight silicone.