“While PVC requires a bit more planning and care upfront, the long-term payoff—a durable, attractive, and long-lasting deck—is well worth the effort.”

 - Jim Coshow

Manufactured decking brands like TimberTech have redefined the reliability and versatility of modern decking. From impressive durability to low-maintenance care, manufactured materials offer a wide range of benefits. But to get the most out of innovative products like TimberTech decking, it’s important to move beyond surface-level features and understand the nuances of each material—and the best practices for working with them.

In our TimberTech series, we're joined by Pat Maher, product application manager and head of AZEK University (TimberTech is an outdoor living brand of the AZEK Company). TimberTech is an industry leader in manufactured decking and a longtime Dunn Lumber partner. Pat brings a lifetime of experience in building materials, with 20 years focused specifically on manufactured decking. We’re excited to share his unique and seasoned perspective.

At a glance

In today’s episode, Pat shares essential tips for installing TimberTech Advanced PVC decking. Learn how to plan for expansion and contraction, maintain proper spacing by following best practices, and reduce butt joints with smart design strategies like divider boards and picture framing. Plus, we cover the best fasteners for Advanced PVC decking, why screw placement matters, and how PVC delivers superior fire resistance for peace of mind. While PVC requires a bit more planning and care upfront, the long-term payoff—a durable, attractive, and long-lasting deck—is well worth the effort.

Watch the video above, or read a summary of our conversation below.

Expansion and contraction do’s and don’ts

One of the biggest points of emphasis when planning for the installation of PVC boards is the possibility of expansion and contraction. Because of PVC’s cellular core composition, the air cells function like balloons. When PVC is cold, the cells will contract and shrink the board slightly. When PVC heats up, the cells will expand and slightly increase the size of the board, mostly in length. It’s worth noting that when the boards do expand, they’ll only expand until they meet resistance. 

With this in mind, TimberTech recommends installing PVC boards when the weather is cooler and always butting the boards tight.

TimberTech also recommends measuring and cutting your boards in the same cool weather—ideally immediately before installation. With this approach, you can prevent unwanted gapping that comes with cutting and installing a warmer board. Cutting and properly installing a cooler board will result in less visible gapping and a more aesthetically pleasing end product.

Best practices for spacing

Uniform, clean spacing is essential not only for deck aesthetics—but also for the longevity of your deck. For PVC decking, TimberTech recommends a ⅛” gap between boards (side to side) mostly for proper drainage and airflow. Maintaining airflow around the framework of your deck goes a long way to prevent moisture buildup and premature structural damage.

When installing PVC boards, you might choose to have butt joints (adjoining the boards end-to-end). Regardless of the temperature at installation (preferably cool), always keep joints as tight as possible. Because the PVC boards expand only until they meet resistance, tight joints won’t gap. The same goes for aligning the boards to railing posts, picture framing, and where boards meet adjacent structures like a home.

Like many manufacturers, TimberTech recommends making fresh, clean cuts on both ends of each board before installation instead of relying on factory ends. Their PVC boards are intentionally made slightly oversized (e.g., 20’ 3” vs. 20’) so installers can square up ends precisely when on-site.

Creative ways to reduce butt joints

To reduce the number of butt joints—and the risk of visible gapping—consider using divider boards. These are boards placed perpendicular to your decking to break up long spans, eliminating the need for end-to-end seams in those sections.

Picture framing is another strategy that offers aesthetic and functional benefits. This design approach involves using one or more decking boards to create a frame around the perimeter of your deck. By using single, double, or even triple picture framing, you can add to the overall length of your deck and possibly get by with 20’ deck boards, eliminating the need for butt joints altogether. While picture framing requires careful planning and precise execution, the finished look is clean, attractive, and professional.

Recommended fasteners for Advanced PVC decking

When it comes to fasteners for PVC decking, TimberTech offers a few excellent options. The most secure methods are:

  • Color-matched screws: Installed from the top down, these provide a straightforward, secure hold directly into the frame.

  • Cortex Hidden Fastener System: This system uses a countersunk screw followed by a color-matched plug, concealing the fastener for a seamless finish.

Both approaches ensure the board is tightly secured and resists movement over time.

Clip systems are another popular option. With the TimberTech CONCEALoc® Hidden Fastener System, fasteners slide into grooves on the board edges, securing them to the frame without visible screws.

When using clip systems on Advanced PVC decking, it is recommended to add some screws at the ends of your boards. To reduce stress on the screws in the last joist—and avoid potential fastener failure—place additional screws on 1-2 other joists leading up to the end. This distributes pressure more evenly.

Finally, screw placement is key. Unlike composite boards, TimberTech recommends placing screws closer to the edge—within ½”—to limit movement from temperature fluctuations. And thanks to the PVC core, screws collapse interior air cells upon insertion, preventing internal pressure from building and reducing the risk of splitting.

Fire resistance: A growing priority

The risk of wildfires is no longer limited to the West Coast. Each year, wildfires increase in severity across the United States, making fire-safe construction materials a nationwide concern. One important way homeowners can prepare is by choosing products that meet Wildland Urban Interface (WUI) codes.

TimberTech’s Advanced PVC decking is one such material. As we discussed in a previous episode, two of TimberTech’s PVC lines—the Vintage Collection® and Landmark Collection®—carry the American Society for Testing and Materials (ASTM) Class A Flame Spread Rating, meaning they won’t accelerate the spread of fire. They also carry an Ignition Resistant designation, indicating the material won’t ignite from surface-level sparks or embers. For added peace of mind, PVC is the best option when it comes to ignition risk and fire resistance.

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