Polyurethane On Concrete? (Here’s How To Apply it)

Polyurethane sealers protect the surface underneath from water, moisture, scratches, and more. So, can you use polyurethane on concrete?

You can use polyurethane over the interior and exterior concrete surfaces. The sealant will form a thick and durable layer that will protect it. The thick layer is moisture and water-resistant. 

However, you must know the right type to use. We explained all you need to know down below.

Oil-Based Polyurethane

You can apply oil-based polyurethane over concrete. It will produce a tough layer over the surface. It also has impressive adhesion qualities, so it sticks to concrete floors and patios. 

Oil-based polyurethane lasts longer on concrete because it uses oil as its solvent. Since oil takes longer to evaporate, its paint particles have more time to harden before drying. This results in a tougher and more durable coating. However, this also means the sealant takes longer to dry.

For outdoor concrete, you must use exterior polyurethane as it s UV resistant and has more additives to protect the surface from weather elements (rain). If you use interior polyurethane over outdoor surfaces, the finish won’t last long. After a while, the rain will slowly vanish the coating and penetrate the concrete.

Related Read: How To Paint Over Concrete Sealer?

Varathane vs. Varnish Polyurethane

You shouldn’t use varathane polyurethane over a concrete surface because it will have a yellow-tinted color. Also, it doesn’t stick well to self-leveling surfaces such as concrete. Plus, this sealer isn’t as durable as oil-based polyurethane. However, you can use it for low-traffic outdoor surfaces. 

For outdoor surfaces, varnish polyurethane is better as it self-levels and penetrates the surfaces better. It also protects it from dust, debris, water, moisture, and scratches.

How To Apply Polyurethane On Concrete?

Concrete decks, floors, and patios are becoming more popular in public buildings and homes. To protect them, you must seal them with polyurethane. Here’s how to do it:

Here are a few steps that will teach you how to apply polyurethane on concrete.

1. Clean The Concrete

The surface must be dry and clean for the sealant to stick. So clean it:

To clean un-painted surfaces:

  1. Pour mineral spirits over oil spills, stains, or dirt.
  2. Use a cleaning brush to scrub the surface. 
  3. Once the surface is clean, remove the residue of the mineral spirit with clean water. 

You can use TSP or pre-paint cleaner as an alternative to mineral spirits.

To clean painted surfaces:

  1. Use soapy warm water or TSP. 
  2. Pour the soapy water over the concrete and use a soft brush to scrub the dirt. 
  3. After you remove the dirt, clean the soap residue with clean water. 

To clean concrete floor: 

  1. Use a concrete cleaner. 
  2. Use a scrubbing broom, and scrub the dust off the floor. 
  3. To be more efficient, work in batches across the room. Or, buy a kit to resurface the floors. 
  4. Water down the whole floor with clean water. 

2. Wait For the Concrete To Dry

To remove the cleaner residue from the surface, use a power washer, or water hose.

Once its surface is clean and the cleaner residue is removed, wait until it dries. To speed up its drying process, squeeze the water off the surface. However, you still must wait 1-3 days for the concrete to dry. 

3. Use Concrete Filler

If the surface is cracked, has holes, or is damaged, you must fix it before sealing it. If you don’t, the sealant will soak into the holes, and the finish will be uneven. 

To repair cracks:

  1. Use concrete filler or restoration caulk.
  2. Squeeze the caulk into the cracks or holes and fill up as much as possible; don’t leave gaps between cracks, and fill the holes full.
  3. Use a towel to remove the excess restoration filler, and let it dry. 

4. Mix the Polyurethane

Before applying polyurethane, you must stir (or mix) it. To mix it, use a turning stick to stir the sealer for 5 minutes. Don’t stir too hard because air can get trapped inside the container, and you will get a bubbled finish.

If you don’t mix it, the finish will be inconsistent and won’t dry properly. 

5. Apply The Polyurethane

To apply polyurethane, use a paint roller or paintbrush. For small surfaces, use a paintbrush. For larger surfaces, use a paint roller. Pour a small amount of polyurethane over the large floor, then use a paint roller to spread it equally. 

You must apply 1-2 coats for low-traffic surfaces and 3-4 coats for high-traffic surfaces. Wait until one coat dries before applying the next one. If you re-coat too soon, the finish will tun sticky and might peel off.

How Long Does it Last?

Water-based polyurethane can last up to 5 years, while oil-based polyurethane lasts 10 years over a concrete surface.

However, the durability of the sealers also depends on how much the surface is used. For high-traffic concrete, the sealant won’t last more than 3-4 years. For low-traffic surfaces, it will last up to 10 years. 

The finish will last less if the surface is exposed to rain. That’s because polyurethane is only water-resistant, not waterproof. So, after a while, the rain will dissolve it and expose the surface underneath to water.

Related Read: How To Apply Polyurethane on Metal?

Final Words

Polyurethane is a great choice for a concrete surface. It protects the surface and paints underneath from water, moisture, scratches, dust, debris, and more.

However, you must use the right type. Use oil-based, exterior, or varnish polyurethane to get maximum protection. If you use varathane or water-based polyurethane, the sealer won’t protect the surface as much. 

Leave a Comment