How to render a painted blockwork house?

[Robyc82]

I’m planning to try and render the outside of our blockwork house in cairns .  It’s currently painted block, do I need to strip the paint? Or would a primer work before the render ? Any help for outside rendering in FNQ would be helpful Thanks , 

[JacobZ]

Hi @Robyc82,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Unfortunately, you would have to strip the paint. The problem with rendering over paint is that the render is sticking to the paint and the paint is sticking to the block, so the render is entirely reliant on the strength of the paint sticking to the block. If the paint loses its grip on the block and begins to peel away, then the render will come with it.

To strip the paint, you can use a chemical stripper such as Polystrippa 4L Paint Stripper with a scraper to remove the paint. Something like this Carinya 1.2m x 150mm Floor Scraper might be a good tool to use, considering the large area.

Any stubborn paint could be removed by grinding it off with an angle grinder using something like this Josco 125mm Twistknot Wire Wheel Brush.

Alternatively, you could contact someone who specialises in paint removal using sandblasting tools.

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

Jacob

[Robyc82]

Thanks Jacob, appreciate the info!