Hi Robert. We have an article here that explains how to fill contraction joints in the middle of the floor. We also list the various materials you can use and where to purchase them. If you want to fill the expansion joints at the perimeter of the slab, you can do that by applying a self-leveling polyurethane joint sealer, such as SikaFlex SL, after the floor coating is completed.

Hi Ronda. The preferred method for applying new coatings to existing coatings is to degrease the surface and then rough it up via sanding. You can learn the process here. If you are applying a quality coating over an EpoxyShield coating, we highly recommend removing the EpoxyShield first via grinding. The entire coating system is only as good as what it is adhered to. EpoxyShield is a low-budget, low-quality coating that is known for adhesion issues with hot tires. If you are applying a coating within the Rust-Oleum family, then you can apply the Rust-Oleum Recoat Primer providing the current coating is still adhered well and not too worn out. You can learn more about Recoat Primer here. Do not use Rust-Oleum recoat primer if the new coating is not in the Rust-Oleum family.

Hi David. Pressure washing is not a recommended or approved concrete preparation procedure for thermosetting floor coatings (epoxy, polyurea, etc.). Etching is typically the minimum acceptable procedure for most coatings. Grinding is the industry standard for commercial quality coatings. Because you have broom finished concrete, we recommend grinding. If you etch, the thin raised edges of a broom finish provides a weak layer for coatings to adhere to. Grinding will knock down all those raised edges and provide a more suitable profile and surface for a quality coating. After grinding, vacuum the surface well with a shop vac. A little bit of dust on the surface is acceptable. However, if feel there is too much after a good vac, then apply denatured alcohol or equivalent liberally to a microfiber mop and wipe the surface down to remove it.

The last thing you want to do is introduce water to the concrete after grinding if you can help it. If you do, you will need to wait a few days for it to completely dry out. Pressure washing will drive water deep into the freshly open pores and you will have to wait even longer. If you don’t wait, the water within the concrete that is still evaporating will play havoc with the epoxy as it cures.