Q&A for How to Seal Concrete Floors

Sealing is needed mainly for preserving the color and preventing stains. It doesn't let water penetrate into the concrete and makes it just slide off the concrete, so it is protected from stains this way.

Water based sealers will work fine as long the the surface is dry when applied.

No, you do not have to.

Any time you're applying a sealer, you want the best possible surface for adherence. Remove dirt, grease, wax and any loose material. There are different requirement for different products and conditions. Manufacturers usually have websites for their products that show what to do and how to use their products.

It depends on the sealer. Some will do fine over paint, but you should ask at your local hardware store for advice.

Clean the floors and use a concrete sealer to reseal it. You can use a sprayer instead of a roller.

It likely will, but you may need to do some prep work, like sanding the floor to roughen it up.

Sealing will likely prevent this problem, though you'll need to clean the concrete thoroughly first.

It depends. Newly poured concrete floors generally do not require etching, although any residual dust or dirt should be removed. Note that for new pours you will want to allow a minimum of 28 days for the concrete to fully cure before sealing. For existing concrete floors, etching is required in order to remove any accumulated oils or other deposits.

Go to a flooring company and ask for a primer for the type of floor covering you intend to use. If the floor surface is rough you will need a latex skimming compound.

It usually depends on what product you're going to use, what you want or expect the product to do and what conditio/environmental factors might affect that outcome.

Concrete doesn't sweat, so you don't need to worry about that.

As long as it doesn't get rained on like a porch or floods like a basement, it will be fine.

Yes, some sealing kits come with grit that you can sprinkle over the floor as it's drying. The grit provides better traction.

It can be, but it's going to be more difficult that way. Plus, you'll get hard edges where the sealer has dried at the edge of the section.

It's just a mild acid used to help clean the floor. You should avoid getting it on your skin.

It depends on the sealant. Some last as long as 20 years, while others will only last 5 or so.

Most sealers can take cold, but silane or siloxane sealers, which penetrate the floor rather than sitting on top of it, may work best.

You should wait at least a month after concrete is poured to seal it, as it needs that time to cure.

Yes, you can seal walls as well as floors. Sealing walls will help keep the moisture out.

It depends on what kind of finish you want for your concrete floors. For an easy seal on interior floors, go with an acrylic sealer. If you want a colorful, durable finish, choose an epoxy sealer for your concrete floor. If you want to apply a sealer on top of an existing sealer, use polyurethane. But if you want the sealer to look the same for a long time, go with a silane or siloxane sealer.

Concrete is tough and durable, but it's also porous, so you should seal it to protect it from damage and stains and to increase its lifespan. Choose a sealer that's appropriate for your floor and apply it to the surface of the concrete to protect it from damage and to lock out moisture that can expand and contract with the temperature, which will cause cracks to form.

Yes, you can absolutely seal old concrete. In fact, you should! But first, make sure you clean it really well and fill in any cracks with concrete repair caulk so you have a smooth and consistent surface. Then choose a sealer that's right for you and apply it to the surface of the concrete to keep it lasting for a long time.