How to Deal with The Scalloped End of Composite Decking?

Composite decking is a popular choice for outdoor spaces due to its durability, low maintenance, and wood-like aesthetics. However, the scalloped (or hollow) ends of these boards can pose challenges if left untreated. Exposed ends may collect moisture and debris, leading to warping, weathering, or reduced lifespan. Properly finishing these ends can extend deck life by up to 30% by preventing water intrusion.

COOWIN has a variety of design solutions. This article will detail the many ways to treat the scalloped ends of composite decking. It will help you choose the best option for your budget, design needs, and construction conditions.

Picture Frame Border

Photo frame edging is a method of hiding scalloped ends by laying one or more layers of trim around the perimeter of the deck perpendicular to the main deck boards. This method not only covers the cut ends but also adds a design touch to the deck.

Advantages:

• Aesthetics: The photo frame border provides a sophisticated look to the deck that suits a variety of design styles.
• Versatility: You can choose boards that are the same color as the main deck to create a sense of unity, or use contrasting colors to add visual impact.
• Protection: Covering the cut ends prevents moisture and debris from entering, extending the life of the deck.

Disadvantages:

• Higher Cost: Additional joists and blocking are required to support the edge boards. Adds $200–$500 in materials and labor for a 100 sq ft deck.
• Complicated Construction: Requires precise miter joints. Poorly cut corners can open up over time and let water in.

Step-by-Step Installation:

• Plan framing: Add extra joists and blocking around the perimeter to support the picture frame boards.
• Cut border boards: Measure carefully and miter corners at 45 degrees for seamless joins.
• Install: Secure the border boards perpendicular to the main deck boards. Use hidden fasteners or color-matched screws, and follow the manufacturer’s spacing and fastening rules.
• Finish: If your decking brand recommends it, apply a suitable sealant or end coating at cut joints to improve weather resistance.

Raised Composite Fascia

Fascia boards cover the deck’s edges and joists, using matching or coordinating composite material for a clean, continuous finish.

Advantages:

• Simple Installation: Attaches directly to the rim joists without major changes to the deck framing.
• Protective: Covers exposed structural parts and board ends, helping to limit UV and moisture exposure.

Disadvantages:

• Risk of Water Accumulation: Water can accumulate in the gap between the fascia board and the joists, leading to corrosion.
• Limited Aesthetics: The design of the fascia is weak compared to a picture frame border.

Step-by-Step Installation:

• Measure and cut: Fit fascia to the rim joists, leaving the manufacturer-recommended expansion gaps (often around 1/8 inch).
• Pre-drill: If recommended, use an appropriately sized bit near board ends to reduce the risk of cracking.
• Secure: Drive fascia screws at regular intervals, typically every 12–16 inches, or as instructed by the manufacturer.
• Seal: If required, apply a compatible sealant or flashing tape at the top edge where the fascia meets the deck. This helps shed water away from the framing.

Paint the Ends of the Composite Deck

The stucco method hides the scalloped ends by painting the cut ends of the composite decking to match the color of the main deck. Use acrylic latex for better adhesion on composites. However, painting the end of the deck may result in an unsightly appearance due to color differences.

Advantages:

• Low Cost: Only paint and tools need to be purchased, no additional materials are required. $20–$50 in paint/tools.
• Quick Construction: It is ideal for small areas, touch-ups, or when structural changes are not feasible.

Disadvantages:

• Poor Aesthetics: Paint may not exactly match the color and texture of the composite decking.
• Low Durability: Paint may flake within 2–4 years outdoors, requiring repaints.

Step-by-Step Installation:

• Clean ends: Remove all dust and debris. Lightly sand only if your decking and coating manufacturers recommend it, then wipe the ends clean.
• Prepare surface: Use a compatible composite end coating or an exterior-grade acrylic latex paint approved for your decking.
• Apply: Use 2–3 thin coats instead of one thick coat. Allow proper drying time between coats as directed by the coating maker.
• Maintain: Check coated ends regularly and reapply as needed when you see fading, peeling, or wear.

Glued Veneer Cap

A veneer cap is a sheet of material that is glued over the cut end of the composite decking to match the color and texture of the main deck. In addition, the installation process requires special care. This is because if the glue fails, the finish will also fail.

Advantages:

• Aesthetically Pleasing: Can provide a nearly seamless color and texture match when carefully executed.
• Protective: Acts as a physical barrier against direct exposure to the elements.

Disadvantages:

• Complex: Requires precise cutting and fitting, as well as careful adhesive selection and application.
• Durability Risk: If the adhesive is not compatible or is applied incorrectly, the veneer may loosen or fail in wet or high‑movement conditions.

Step-by-Step Installation:

• Cut veneer: Rip thin strips or caps that match the width and thickness needed to cover the scalloped ends.
• Apply adhesive: Use a high-quality, exterior-grade adhesive that is compatible with your composite material. Follow the adhesive maker’s instructions for surface prep and application.
• Clamp and cure: Press the veneer firmly into place and clamp it as required. Allow the adhesive to fully cure before exposing it to heavy use or moisture.
• Trim and finish: Carefully trim or sand any excess material and smooth the edges for a clean, integrated look.

End-cap

An end cap is a plastic or composite cap specially designed to cover the cut end of a hollow or ridged composite decking.

Advantages:

• Easy to Install: End caps can be inserted or tapped directly into the cut end.
• Protective: Helps prevent insects, small animals, and debris from getting into the hollow cavities.

Disadvantages:

• Limited Compatibility: Not all composite decking brands offer matching end caps.
• Average Aesthetics: The color and texture of the end cap may not exactly match the main deck.

Step-by-Step Installation:

• Clean ends: Remove dirt, debris, and any loose material from inside the hollow sections.
• Insert: Align the cap with the board cavity and gently press or tap it with a rubber mallet until it is fully seated.
• Secure: If recommended, apply a compatible adhesive or fastener to improve retention in high-traffic areas.

Other Methods

In addition to the 5 methods recommended above, there are several other methods, including:

• Vinyl Stair Leading Edge: Vinyl stair leading edge is an affordable solution for covering the cut ends of composite decking. It is easy to install and costs less. However, it is less aesthetically pleasing.
• Corner Trim: Corner trim is an L-shaped material that not only covers the ends well but also hides the grooved sides of the deck. It is suitable for areas that need extra protection.
• Bullnose Boards: Bullnose boards are solid boards with rounded edges on one side and are suitable for decks that need a firmer edge. Most bullnose boards must be installed before the rest of the boards can be installed. This is because bullnose boards require a clip to be installed underneath themselves.
• Ground Edges: For ground-level decks where panels, trim boards, or other methods don’t work, you can try edging the deck with a variety of materials. For example, you can surround the edge of the deck with stones, bricks, pavers, or gravel. Not only is this aesthetically pleasing, but it also improves drainage.

Comparison of Common Methods

Note: Cost and difficulty ratings are approximate and will vary based on product line, local labor rates, and installer experience. Always check your manufacturer’s specific recommendations.

How to Choose The Best Method?

Depending on your needs, COOWIN can help you design a treatment plan for the scalloped ends of your composite decking. When choosing a method of treating the scalloped end of composite decking, you need to take into account the following factors:

• Budget: Picture frame borders and fascia boards are more costly, while the stucco and end cap methods are more economical.
• Aesthetics: Picture frame borders and veneer caps provide the best aesthetics.
• Construction Difficulty: The end cap and stucco methods are suitable for DIY, while picture frames and veneer caps require specialized skills.
• Durability: Picture frames and fascia boards provide better protection and extend the life of the deck.

Conclusion

Treating the scalloped ends of composite decking is a critical step in ensuring the beauty and durability of your outdoor space. Whether you choose a picture frame border, fascia board, stucco method, or another method, the decision should be based on your specific needs and conditions.

With proper planning and construction, you can create a flawless end-treatment solution for your composite decking that will enhance the overall value and experience of your outdoor space. If you still don’t know what to choose, you can contact us. COOWIN has a professional service team to solve your problems.

FAQ

Does end treatment affect my decking warranty?

It can if you use unapproved coatings, adhesives, accessories, or installation methods. Always review your decking manufacturer’s warranty and installation guide, and follow their approved practices.

What are common mistakes when finishing scalloped ends?

Common mistakes include:

• Skipping expansion gaps, which can lead to buckling.
• Not pre-drilling where required, which increases the risk of cracking.
• Blocking ventilation behind fascia or trim, which traps moisture.
• Mixing incompatible materials may deteriorate faster or compromise the installation.

Can I mix different methods on the same deck?

Yes, many homeowners combine methods. For example, you might use a picture frame border on the main perimeter and end caps on less visible sides. Just make sure all methods are compatible with your decking brand’s guidelines.