How to fix gap in corner of wall?

Hi All - first time poster but have always read through some of the posts here for tips!

I need some help with what steps and tools I need to follow to fix up this gap in the corner of the wall.

This started out as water damage which was caused by a broken tile (which has now been fixed).

What I’ve done so far is to remove all the loose paint which also ended up removing what I think is the plasterboard paper (as you can see there is a gap now in the corner)

Afterwards, I sanded the area down to ensure everything is as smooth as can be.

At the moment, I’m a bit stuck as to whether this job I’m fixing this is too difficult for me or if I need to hire someone to help.

I am always up for DIY, hence reaching out to this community.

If someone can help me with:

1. The tools and products I need to fix this. Ideally if there are ready-made products, that would be easiest for me.

2. The steps and instructions to follow

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MitchellMc

Welcome to the Bunnings Workshop community @jasonatam. It's fabulous to have you join us, and many thanks for your question about repairing a gap.

It would be helpful if you could tell us a little more about where this gap is located. Is it in a bathroom or wet area, or is it somewhere away from the tile and timber that originally caused the damage. Knowing the location will help us guide you toward the right type of filler, because standard fillers behave differently from wet area products.

This looks like a straightforward repair that you can definitely tackle yourself. If it is just a normal internal corner, you can push some backing rod into the gap first so the filler has something to sit against. This prevents it from falling through the opening. Once the rod is in place, you can use a caulking filler to bridge the gap. For dry areas, a standard flexible gap filler is fine. For bathrooms or any area exposed to moisture, a wet area gap sealant would be more appropriate.

Apply the gap filler with a caulking gun down the gap. Smooth the filler into the corner with a caulking tool or your finger, then allow it to dry. If sanding the loose material has caused the surrounding surface to sit a little low, you may need to apply a thin skim of plaster-based filler over the top to level the surface before painting. After it dries, give it a light sand so everything blends back into the wall.

Here's a helpful guide: How to apply silicone sealant.

Please let me know if you have any questions.

Mitchell

jasonatam

Thanks for your reply Mitchell - the repair is in our bedroom, inside our wardrobe area, top corner of the roof.

I was doing some YouTubing and would the products below be sufficient?

Aisle 5 - Gyprock CSR 2.25kg Less Mess Multi-Purpose Joint Compound
Aisle 5 - Builders Edge 50mm x 20m Fibreglass Builders Joint Tape
Aisle 6 - Builders Edge Internal Corner Plaster Tool

Planning to first use the fibreglass joint tape to tape up the corner gap.

Then followed by joint compound to apply the first layer onto the tape.

After drying, will repeat for 2 more layers.

After compound is all dry, then sand it back down to smooth, then paint 2 layers.

Its slight different to what you advised, but is there anything else here that I should consider or can do better?

MitchellMc

That approach will certainly work @jasonatam, and it is a perfectly valid way to repair the corner. Just keep in mind that the method you have outlined is more involved than simply filling the gap with a flexible gap filler, so if you are still weighing up whether this is within your comfort zone, your proposed method does add a few extra steps.

That said, using the fibreglass tape and a joint compound will generally give you a cleaner and more seamless finish. Because you are working with a plaster-based compound, you can build it up in layers, sand it smooth, and recreate the internal corner far more precisely than you could with a standard gap filler. A caulked filler is really a one-and-done product: you fill the gap, smooth it, and whatever shape you get is what you live with. Your method allows you to shape and refine it as much as you like.

So yes, if you're comfortable giving the tape and joint compound a try, I would recommend that over simply using a gap filler. It will give you the best final result.

Mitchell

jasonatam

Thanks for the quick response Mitchell! I think I’ll definitely try the method I researched then!

I also liked one of the points you mentioned, where you input a backing rod into the gap.

Do you think I can input this backing rod first and then apply the fibreglass tape over it?

Thanks,

Jason

MitchellMc

I don't think you'll need to, as the tape is rigid enough to establish the internal corner and prevent the plaster filler from being pushed inside @jasonatam.

Mitchell

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