Bagging, painting or rendering a block retaining wall?

VBK

We want to cover and add colour (a natural green) to the block retaining wall. We are trying to work out the best method.

An issue we have is moisture. It is coming out of the front bottom of the retaining blocks, so it is not getting drained away and is passing through the front of the retaining wall.    

Despite the retaining wall having a waterproofing membrane placed at the back of the retaining wall when it was built, this didn't stop water from accumulating in the back of the blocks.

Based on this, we are after advice on the best method to cover up the block look of the wall and add some colour.

Thank you in advance.

MitchellMc

Welcome to the Bunnings Workshop community @VBK. It's tremendous to have you join us and many thanks for your question on coating a block wall.

It looks like there’s a consistent moisture issue in the retaining wall, not just at the base but through the face as well. The white salts visible on the surface (efflorescence) indicate that water is moving through the blocks, which means the wall is holding moisture internally. Because of this, applying finishes like paint, render, or bagging directly to the wall is not ideal. While bagging or rendering is possible, you should expect potential problems such as staining, discolouration, and eventual breakdown of the surface. Painting is the least suitable option, as moisture pressure can cause it to peel or blister over time.

A more reliable approach would be to install timber or metal battens onto the wall and then fix fibre cement sheeting over them. This creates an air gap that helps prevent moisture from transferring to the finished surface. You can then safely render, bag, or paint the sheeting in your desired colour. Another option is to attach decorative panels directly to the wall (or onto battens), which can achieve a similar visual result without the risks associated with coating a damp surface.

Please let me know if you have any questions.

Mitchell