How To Finish Composite Deck Stairs

Are you in the process of building a composite deck and struggling with finishing the stairs? Don’t worry, you’re not alone. Composite decking material can be tricky to cut and shape, especially when it comes to stairs. However, with the right tools and techniques, you can achieve a beautiful and functional set of composite deck stairs.

In this article, we will walk you through step-by-step instructions on how to finish composite deck stairs. We’ll cover everything from measuring and cutting the stair treads to installing railing systems for safety.

By following these guidelines, you’ll be able to create a stunning set of composite deck stairs that will enhance the overall look of your outdoor living space. So, let’s get started!

Tools And Materials Needed

Tools and Materials Needed:

Preparing to finish composite deck stairs requires a thorough understanding of the tools and materials that will be needed. First, gather all the necessary tools such as a circular saw, drill, measuring tape, and safety equipment like goggles and gloves.

Second, you’ll need to purchase the appropriate materials for finishing your composite deck stairs. These materials may include composite decking boards, screws, adhesive, and sandpaper.

Composite decking boards are an essential material for finishing deck stairs. These boards are made of a combination of plastic and wood fibers that make them durable and resistant to weathering elements. Additionally, they are available in various sizes and colors that allow you to choose the one that suits your design preferences.

Screws and adhesive are also necessary materials for securing the composite decking boards onto the stair frames. Make sure to use stainless steel screws or coated screws to prevent rust formation.

Lastly, sandpaper is required for smoothing any rough edges or surfaces before applying paint or stain. With these tools and materials at hand, you’re ready to begin your journey towards beautiful finished composite deck stairs!

Measuring And Cutting Stair Treads

Once you have installed the stair stringers, it’s time to measure and cut the stair treads. To ensure a perfect fit, measure each tread individually and mark them with a pencil to indicate where they need to be cut.

Using a circular saw, cut each tread along the marked line. Be sure to wear protective eyewear and gloves while cutting to prevent any injuries.

Once all the treads are cut, it’s time to install them onto the stringers. Start at the bottom of the staircase and work your way up. Place each tread onto the stringer and secure it in place using composite deck screws. Use a level to make sure each tread is even before moving on to the next one.

With these steps, you can easily measure and cut your composite deck stairs’ treads for a perfect finish. Remember to take your time and double-check your measurements before making any cuts. Happy building!

Installing The Stair Stringers

Now that you have completed the framing for your composite deck stairs, it is time to install the stair stringers. This process involves attaching the vertical supports that will hold each step in place. Begin by measuring and marking where each stringer will go, ensuring they are evenly spaced and level.

Next, cut your stair stringers from treated lumber or composite material, following the markings you made. It is important to make accurate cuts to ensure a secure and stable staircase. Once your stringers are cut, attach them to the framing using structural screws or bolts, making sure they are flush against the framing and securely fastened.

To finish off your composite deck stairs, add each individual step by screwing or nailing them into place on top of the installed stringers. Be sure to measure each step carefully to ensure they are even and level. With all steps attached, sand any rough edges or corners before applying a coat of sealant or stain for added protection and longevity.

Pros Cons
Durable Can be slippery when wet
Low maintenance Requires special tools for cutting
Resistant to rot and insects Higher upfront cost compared to traditional wood
Available in a variety of colors and styles May expand and contract with temperature changes
Environmentally friendly option Heavier than traditional wood

As you can see from the table above, there are both pros and cons when it comes to using composite material for your deck stairs. However, with proper installation techniques and regular maintenance, composite deck stairs can provide a long-lasting and visually appealing addition to your outdoor living space.

Attaching The Stair Treads

As luck would have it, attaching the stair treads is a straightforward process.

Begin by measuring and cutting your treads to size, ensuring they are level and flush with each other.

Next, position the first tread in place, making sure it is securely fastened with screws or nails.

Moving on to the second tread, use a level to ensure it is perfectly aligned with the first. Once again, secure it firmly in place with screws or nails.

Repeat this process for each subsequent tread until you reach the top of your stairs.

With all treads securely attached, take a moment to admire your handiwork.

You now have a beautiful set of composite deck stairs that will provide safe and easy access to your outdoor living space for years to come.

Adding Railing Systems For Safety

After completing the construction of your composite deck stairs, it’s important to add railing systems for safety purposes. Railings not only provide safety by acting as a barrier but they also add beauty and elegance to the deck.

You have several options when it comes to choosing the type of railing system that will work best for you.

Firstly, you can opt for a traditional wood railing system that complements your composite deck stairs. This option is relatively affordable and easy to install. However, wood railings require periodic maintenance such as staining or painting to keep them looking good over time.

Secondly, you can choose a composite railing system that matches your deck color and material. Composite railings are low maintenance and durable, making them an ideal choice if you want something long-lasting.

Lastly, you can choose a metal railing system such as aluminum or steel. Metal railings are strong and offer excellent support while also providing an elegant look to your deck stairs. They’re also low maintenance, so you don’t have to worry about rusting or rotting over time.

Whatever option you choose, make sure that the railing system meets building code requirements in your area before installation.

Sanding And Finishing Touches

Sanding is important for a smooth finish, so I’d start there.

After sanding, you can use a sealer or finish to protect the stairs.

Then, you can add some decorative touches, such as a handrail or trim.

Finally, you can add lighting or other accessories to really make your stairs stand out.


Before applying the final touches on your composite deck stairs, sanding is an essential step to ensure a smooth and even surface. It helps to remove any rough spots, splinters and scratches that might have occurred during installation or over time. Sanding also opens up the pores of the wood, allowing the stain or sealant to penetrate better.

To start sanding, use a coarse-grit sandpaper of around 60-80 grit to level out any bumps or high spots. Be sure to sand in the direction of the grain and avoid applying too much pressure as it could damage the material.

Once you have achieved a relatively even surface, move on to a finer grit sandpaper of around 120-150 grit for a smoother finish.

Remember that dust and debris can accumulate quickly while sanding. Therefore, make sure you wear protective gear such as goggles, gloves and a face mask. Also, keep a vacuum cleaner at hand to clear away any sawdust after each round of sanding.

By taking these precautions, you can achieve professional-looking composite deck stairs with ease without compromising your health or safety.

Finishing Touches

Now that you’ve sanded your composite deck stairs to a smooth and even surface, it’s time to add the finishing touches.

The next step is to apply a stain or sealant to protect the material from moisture, fading, and general wear and tear. Before doing so, be sure to clean the surface thoroughly with soap and water to remove any remaining sawdust or debris.

When choosing a stain or sealant, keep in mind that there are different types and colors available on the market. Make sure you select one that complements the overall look of your deck and matches your personal taste.

You may also want to consider a product that includes UV protection if your deck receives a lot of direct sunlight.

To apply the stain or sealant evenly, use either a brush or roller depending on the size of your project. Be careful not to leave any drips or streaks as they can be difficult to remove once dried.

Allow ample time for the first coat to dry before applying another layer if needed.

In conclusion, sanding and finishing touches are crucial steps when it comes to maintaining and enhancing the appearance of composite deck stairs. By using proper techniques and equipment, you can achieve professional-looking results without compromising safety or quality.

So take your time, follow these guidelines, and enjoy your beautiful new outdoor space!

Tips For Maintenance And Longevity

After sanding and finishing your composite deck stairs, you might think that you’re done. However, there are still a few things to consider if you want your stairs to last for years to come.

One theory is that proper maintenance is key to ensuring your deck’s longevity.

While composite decking is low-maintenance compared to wood decking, it still requires some upkeep. Regularly sweeping away debris and cleaning with mild soap and water will help prevent the buildup of dirt and grime that can lead to discoloration or staining.

Additionally, be sure to trim any nearby plants or vegetation to prevent mold growth.

Another tip for maintaining your composite deck stairs is to avoid using harsh chemicals or pressure washers when cleaning them. Instead, opt for gentle cleaning solutions specifically designed for composite decking.

And if you do need to use a pressure washer, make sure the pressure is set at a low level and keep the nozzle at least eight inches away from the surface.

Taking these steps towards proper maintenance can go a long way in extending the life of your composite deck stairs. By doing so, you’ll not only save money in repairs or replacements down the line but also ensure that your outdoor living space remains beautiful and functional for years to come.


In conclusion, finishing composite deck stairs is a great way to enhance the overall look and safety of your outdoor space. By following the steps outlined above, you can create a durable and visually appealing staircase that will last for years to come.

I remember when my neighbor finished his composite deck stairs last summer. He said it was like putting the final puzzle piece in place, completing the picture-perfect backyard oasis he had always envisioned.

And just like a puzzle, each step of building these stairs requires attention to detail and precision. But with the right tools and materials, anyone can accomplish this project and enjoy the satisfaction of a job well done.