How do I repair a large patch of drummy delaminated rendered interior wall?

rchreno

Hi all,

I have a delaminated corner wall that I need to repair. I have opened up the drummy section and cleaned out the area as much as possible. The size of this render patch will be about 150 x 50 cm and about 8mm thick. I'm after some advice to restore this wall in the right way, flush and with the right texture.

I am planning to use bondall bondcrete to seal it before rendering, but which render product would be best for this project? Is it just a single layer application that is screed flush with the rest of the wall, or is it better to have it done in stages like plastering? How do you manage the render so that it doesn't set too quickly, because unlike plastering the margin for error is higher as you can't just sand the render down after it's dry.

I have seen the method on how to render a brick wall and how to repair rendered wall but they are exterior wall and the repair area is small compared to mine. I'm not sure if the product I need for this project would be the same or not, especially to match the texture. What would you recommend?

After rendering the wall, presumably I would need to seal and prime the patch before painting as well? Thanks!

MitchellMc

Welcome to the Bunnings Workshop community @rchreno. It's fabulous to have you join us and many thanks for your question on rendering.

Nice job opening it up and cleaning it out properly.

For an internal patch like this, you’re on the right track with BondCrete as a primer/bonding agent. Just dilute it as per the instructions and apply it to both the brick and the surrounding edges before you start. There's also https://www.bunnings.com.au/dunlop-4l-multipurpose-primer_p0760587 .

In terms of product, a pre-mixed cement render or a bagged interior/exterior render mix will both work well here. Something like https://www.bunnings.com.au/dunlop-16kg-ready-to-go-premix-render_p0760250 or https://www.bunnings.com.au/dunlop-20kg-multipurpose-acrylic-render_p0760242 would work well.

Given the size, I’d recommend doing it in two passes rather than trying to get it perfect in one hit:

• First coat (scratch coat): ~4–5mm thick, pressed firmly into the brick for good adhesion. Lightly scratch it to give a key.
• Second coat (top coat): bring it out flush with the existing wall.

To help with working time, you can:

• Avoid working in hot or very dry conditions
• Mix smaller batches so you’re not racing the set time

For getting it flush, use a straight edge or large trowel across the existing render as a guide. Matching the texture can be a bit of trial and error. You can finish with a sponge float to get a slightly textured look.

Once it’s fully cured:

• Apply a sealer/undercoat (primer)
• Then paint as normal

One thing to keep an eye on is the cracking near the corner in your photo suggests there may have been a bit of movement there, so just make sure everything is solid before patching.

If you want a slightly easier finish internally, another option is to render it close and then skim over the top with a finishing plaster for a smoother, more paint-ready surface.

Please let me know if you have any questions.

Mitchell