How to repair and repaint plastered brick walls?

[ToW]

Hi,

I was hoping you could please give me some advise on the below problem ?

I am planning to repair interior walls / repaint in an apartment built in the 70s. It is a double brick wall - previously painted.

There is some kind of plaster underneath the paint - white/hard but somewhat porous (a bit like multi-purpose gap filler). 

The walls throughout the apartment look like this. I don't think it is water damage, as it looks like that everywhere... probably wrong layering.

I found paint buckets in the garage, so assume the most recent layer of paint must have been applied in the last couple of years.

I am planning to sand / grind off layer 1 / 2 of paint and leave the white plaster-type base - layer 3. Then apply a sealer / binder / base coat before applying primer and paint. Layer 3 you can scrape with a spatula, but it is a lot of effort - so was planning to use my angle grinder.

Grinding it a bit deeper, it looks like this:

What is the best course of action?

Apply Bondall 1L BondCrete Cement Additive - Bunnings Australia or Dulux 4L PRECISION White Sealer Binder - 4L - Bunnings Australia ? What is the difference ?

I was planning to even things out with Gyprock CSR 15kg Easy Flow All Purpose Compound - Bunnings Australia after applying the binder, before the dulux 1 step primer for painting. EasyFlow is a bit more forgiving and easier to sand by hand - I am a novice :). If I use bondcrete - do I let it dry or leave it tacky before applying Gyprock Easy Flow ?

Thank you

Regards

[JacobZ]

Hi @ToW,

A warm welcome to the Bunnings Workshop community and thank you for your question.

It looks like there are two layers of paint over a layer of plaster that was applied directly to the brick. The porosity is common in most types of plaster, and it can be fairly easily rectified by applying a skim coat of topping compound. For this reason, I'd suggest removing the top two layers and leaving the third, assuming it is still well bonded to the surface beneath.

My suggestion is to remove the layers of paint as you had planned, then apply a skim coat of plaster over the existing layer of plaster. A topping compound such as this CSR Gyprock Ultra-Top Topping Compound would be better suited to the job than Easy Flow. Topping compounds are designed to be light, creamy, easy to apply and relatively soft, which makes them easy to sand. These characteristics make them ideal for skim coats. 

After applying the topping compound, you can then apply your primer, with Dulux PRECISION White Sealer Binder, being the ideal choice. As this is a sealer, binder and primer, it will bind and seal the powdery plaster surface, and act as a strong primer between the paint and the plaster surface beneath.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

[ToW]

Thank you, would you use any binder in between the old layer of plaster and the new layer of plaster (i.e. the topping compound such as the gyprock ultra-top topping compound) ? For example, the bondcrete ? I don't completely trust the old layer of plaster that is applied on the brick.

[MitchellMc]

Hi @ToW,

There's no need to use a binder like BondCrete between the old plaster and the new plaster. Plaster generally adheres well to existing plaster surfaces, provided they’re sound. The only thing I’d recommend is to give the old plaster a light spritz with water before applying your new topping compound. This helps prevent the old plaster from pulling moisture out of the new mix too quickly, which can lead to poor adhesion or weak bonding.

In fact, using a product like BondCrete could actually work against you here — it seals the surface, and plaster doesn't like sticking to sealed, non-porous surfaces. It bonds much better to porous materials, which is what you want for a strong, lasting finish.

That said, your concern about not trusting the old plaster might point to a separate issue. If the old plaster is powdery, flaking, or crumbling off the bricks, that’s a sign it’s failing, and it would be better to remove it before replastering. But if you've already tried removing some and needed an angle grinder to do it, that suggests it’s quite solid and well-adhered. In that case, you’re likely fine to simply plaster over the top.

Please let me know if you have any questions.

Mitchell