How to patch cement rendered walls?

[moloko]

Hi there,

I had originally mistakenly thought that my apartment walls were plasterboard. I now know that my walls are cement rendered. I only realised after I'd recently gone and patched up holes and cracks in my walls originally thinking they were plasterboard. I used Bunnings' "Gyprock CSR 1.5kg DIY Rapid Plaster Repair Kit" where the suitable surface is noted as "plasterboard."

Whilst the patch is holding up after drying, I'm worried that i've used the wrong patching material that is meant for plasterboard and not for cement rendered walls. Can anyone advise whether I've gone and stuffed up here and if so, how may i address this? 

I also did not use a coarse brush to stipple (as i now know is the correct way to go about patches to cement rendered walls) when the repair was still wet and workable so it's a dry, smooth surface right now instead of having a stipple look/effect that I realise the rest of the walls have. Does anyone know a work-around for this?

Thanks!

[EricL · Accepted solution]

Hello @moloko

Thanks for sharing your question about patching a cement-rendered wall. The strength of the repair will depend on the thickness you applied to the damaged area. If the surface you covered is very rough the plaster should anchor itself very well to the wall. It would have been an ideal time to stipple the surface while it was still soft, but now that it has cured, I suggest using a Trojan 3 x 14 Row Wooden Wire Brush and lightly tapping the surface to get rid of the smooth finish. It will take some time, but you should be able to get a similar finish as your wall. 

However, you do have the option of removing the plaster patch with a chisel and repatching it with a render. 

If you have any other questions we can help with, please let us know.

Eric

[moloko]

Thank-you for your help @EricL!

[MitchellMc]

Please keep us updated and reach out if you need further assistance @moloko.

If the wire brush doesn't work for you, apply another thin coat of plaster. You'll then be able to stipple that with a brush whilst it's wet.

Mitchell