How Many Coats Of Polyurethane On Stairs?

How Many Coats Of Polyurethane On Stairs

The gorgeous amber shine of a beautiful hardwood staircase will be one of the most attractive features in almost any home. Unfortunately, repeated use can wear down the incredible finish. This is when you need to apply a coat of polyurethane.

Polyurethane is used to restore that gleaming finish for an attractive hardwood staircase. It acts to both bring out the natural finish of the wood and to provide a layer of protection against persistent foot traffic. But how many coats should you apply?

Exactly how many coats of polyurethane are needed depends on several factors. Some stairs may only need two coats, while others could need up to four. In this guide, we’ll give you some tips on how to make your staircase beautiful again, for longer.

How many coats of polyurethane should you use on stairs?

Anywhere between a single coat of polyurethane and four coats of polyurethane may be needed on your stairs. This will depend on the type of wood, the wear the staircase has suffered, and the type of polyurethane you’re using. 

Stairs that have suffered from a significant amount of wear are likely to need more coats of polyurethane. This is both to correct the original damage, and to protect against any future damage.

The type of wood can have a surprisingly strong effect. Some woods are more porous, so will end up absorbing more of the polyurethane. That means the second layer on some stairs will look the same as a single layer on others.

It’s difficult to know how the wood will react until you’ve actually started the application.

Another interesting read: What To Do When Polyurethane Won’t Dry?

Types of polyurethane

There are two types of polyurethane that can be used on stairs: oil-based, and water-based. Each type has an advantage and disadvantage. Which type you choose will have a huge effect on how many coats are needed.

Oil-Based Polyurethane

Oil-based polyurethane is the thicker polyurethane. This makes it easier to apply. Because it’s thicker, only two or three layers are needed for durability. This should last over a lot of usages.

However, oil-based polyurethane takes a long time to dry, which is a disadvantage in a busy household. A tip to get around this is to work on alternating steps at a time. This will take a while, but it prevents damaging drying polyurethane.

The oil-based options also have a slight amber finish, which can show scuff marks. It also has a strong smell.

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Water-Based Polyurethane

Thinner than oil-based options, water-based polyurethane can dry quickly. It needs more layers for a strong finish, but this can often be applied in a single day. Quality water-based polyurethanes dry clear and don’t smell strong.

However, they don’t have the same durability as a good oil-based polyurethane. 

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How to apply polyurethane to stairs

How Many Coats Of Polyurethane On Stairs?

Sand Down the Stairs

Begin by sanding down the stairs. Use 120-grit sandpaper, and gently sand down the wood to an even finish. In some cases, it may be better to start with coarse sandpaper and finish with a fine one.

Clean the Area

Clear the area completely. Vacuum away any remaining dust or grit, and then wipe the stairs down with a tack cloth. If you’re using water-based polyurethane, wipe the dust away using a cloth damp with water. If using oil-based polyurethane, dampen the cloth with mineral spirits.

Invert Polyurethan Can

Gently invert the can of polyurethane 10 times. This is to stir the mixture. Do not shake. Shaking forms bubbles, and these can ruin the finish. Throughout the application process, repeat this stirring process.

Apply the Polyurethane

Use a fine bristle brush if you’re applying oil-based polyurethane. For water-based polyurethanes, a sponge brush works best. Use long and smooth brushstrokes, and follow the grain of the wood. Overlap each stroke, to maintain consistency. If applying to curved areas, use a sponge or cloth. A brush can result in drips.

Leave the Polyurethane to Dry

Wait at least 24 hours for an oil-based option to dry thoroughly. A water-based finish can dry in a few hours. The polyurethane must be completely dry before you attempt the next step.

Sand Down Any Uneven Areas or Drips

Use fine-grit sandpaper, and dampen it. Wet sanding helps to create an even finish. Only sand until the surface is smooth, and be careful not to overdo it. Wipe the surface down with a wet cloth, and leave it to dry.

Apply a Second Layer

By the time the second coat has finished drying, you should be able to see how necessary another coat is. If you’ve used a water-based polyurethane, then at least a third coat should be applied. For an oil-based polyurethane, those two coats might be enough. 

Can you add too many coats of polyurethane on stairs?

You can’t really add too many, but after a while, there really isn’t any point. It will be harder to maintain an even surface, and you may find that each sanding is stripping away as much of the polyurethane as you’re applying.

If you’re applying more than four layers, then you’ll start to find the finish takes a very long time to dry. It can also become thick, almost gooey, and it may even start to peel. Multiple layers of oil-based polyurethane can turn yellow over time. 

After four coats, there isn’t any benefit to applying more layers. If you find your stairs still don’t have the finish or protection you’re after, then it might be you’re using the wrong brand of polyurethane. Look for quality options, which will need fewer layers for a better shine.

Final Thoughts

Two to four coats of polyurethane should be enough for any staircase. 

Two layers of an oil-based polyurethane are often enough, but this may take several days to apply. Four layers of water-based polyurethane might be necessary, but quick drying times mean this can be accomplished in a day.