Water – How to paint concrete blocks without trapping moisture

concrete-blockpaintwallswater

I have a shed/laundry that is a separate building from my house. It's made of concrete blocks sitting on top of a poured concrete slab. Currently the inside is bare, which is dark and drab. I want to brighten it up. I was thinking of painting it, or maybe tiling (although I don't want to spend much effort). The outside is already painted.

But, the building has a flat roof with narrow eaves, and the outside of the wall gets wet. Sometimes after a lot of rain the inside of the wall looks damp. It's possible that the gutters overflow a little bit inside, but this will be difficult to fix because the roof is shared and controlled by a poorly-funded body corporate.

I'm worried that if I paint the walls the bricks will stay damp for longer, which might smell and eventually cause structural problems. Or maybe it's not an issue because the blocks are hollow? We don't get freezing temperatures here, so I'm more concerned about things like concrete cancer and mould than cracking.

My question is: how can I brighten the inside of the shed without causing long-term maintenance problems?

Best Answer

Seems like a shoddily built roof. So, I think the roof will fail long before painted walls will cause a problem.

It sounds like the outside paint is already 'breathable' if it's absorbing water and capillary action is bring it to the inside. As such, I'd argue that waterproofing the interior is a good thing. Keep the moisture in the wall and allow it to dry to the outside.