Hello,

I need to seal the inside of a basement with block walls and concrete floor. Block and concrete are in good condition. The problem is dampness and minor mildew but not leaks.

Walls and floor were painted. Paint on walls is peeling in some areas due to eflourescence underneath.

What is the most effective sealing solution? If I need to remove the old paint what is the best way to do that?

(I will also be installing a drain system under the floor which should help a lot but still need to seal the walls and floor).

Thanks.

You need to remove the old paint completely using a wire brush or sand blaster. The best block sealing is done from the outside but if you want to try your approach you can. You then coat with a high quality block filler designed to give a water proofing bond to the block. Research on your own and you can start here Find Block Filler and other Specialty Paint Products at Aubuchon Hardware

Thanks for the suggestion. From past research I am aware that there are many different products out there some of which are more of a masonry / silica base, some are more of a paint. Most require removal of the old paint and acid removal of the eflourescence. My concrete installer also mentioned that there are new do-it-yourself products that can be put over old paint.

To clarify my question, has anyone used a product in a similar situation and had good luck with it? This will be a lot of work and I don't want to end up with another layer of failed product to remove and replace. Thanks.

I have a similar situation and I have used a product called Drylok. I scraped and wire brushed any loose paint and applied one thick coat of Drylok. The product is very thick and one coat seemed to work well. I'm going to use it on an area in my basement that gets a little moist when it rains. I'm very pleased with it.

Hope this helps! :)