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Hi,
I noticed last night that one of the windows in our bathroom is missing caulk on the left long side.
Just wondering the best product to use to seal this? The gap is around 4mm.
I understand I will need to use rubbing alcohol to clean it up before applying the caulk is this correct also?
Sorry very new to any house maintenance so apologies for the questions and possible incorrect naming
Welcome to the Bunnings Workshop community @notsure2026. It's terrific to have you join us, and many thanks for your question about filling a gap.
No need to apologise at all, this is a very common question and you are looking at exactly the right thing.
For a bathroom window like this, the best product to use is a wet-area silicone sealant. Silicone stays flexible and handles moisture much better than standard gap filler, which is important around windows in bathrooms. Only use a paintable gap filler if you are certain you want to paint over it afterwards, as silicone cannot be painted.
You do not need rubbing alcohol specifically. The main thing is that the area is clean, dry and free of dust, soap residue or loose material. A wipe with a damp cloth, followed by letting it dry, is usually enough. Alcohol is sometimes used by professionals, but it is not essential for a small job like this.
With a 4 mm gap, silicone is perfectly suitable. Masking tape along both sides of the gap is a great idea, as it helps keep the bead neat. Apply a steady bead of sealant, then smooth it with a lightly wet finger or a finger dipped in soapy water. Once you are happy with the finish, remove the tape straight away while the silicone is still wet.
Take your time and do not overthink it. This is a straightforward job and a great place to build confidence with basic home maintenance.
Here's a helpful step-by-step guide: How to apply silicone sealant.
Please let me know if you have any questions.
Mitchell
Awesome thank you! So this one should be ok for drywall and wood? It just doesn’t say in the description 
@MitchellMc
Drywall and wood are not listed as it's typically used around direct wet areas and fixtures @notsure2026. However, you're applying it to a painted surface, such as the drywall and timber, which I believe is fine. It might actually be exposed timber in the gap. Silicone sticks to just about anything, so it should be all good.
Let me tag @Nailbag for his thoughts. My only concern is using a standard gap filler in a bathroom if you are not going to paint over it.
Mitchell
The reason I'm second-guessing myself is that recently I caulked a couple of bathrooms around the ceilings, walls and windows with Selleys 475g No More Gaps Interior Multipurpose Gap Filler. They were not in immediate wet zones, similar to your situation. However, after completing the job, I was thinking to myself, should I have used a dedicated wet-area silicone sealant? I think I'm just being over-cautious, and unless it's in a shower recess or a joint that will experience regular wetting, the standard filler linked here is sufficient, even without painting it. It does state in the technical data that it is not suitable for submersion or constantly damp areas, which would not be the case with your windows.
I'd go with the Selleys 475g No More Gaps Interior Multipurpose Gap Filler, which is suitable for drywall, wood and painted surfaces.
Mitchell
