Composite vs PVC decking: what's the difference for Boise?

How do composite and PVC decking compare?

PVC buys moisture resistance, lighter boards and, in certain lines, better fire ratings for a higher price. Composite covers most decks well for less. The table sets them side by side.

What's inside each board

The core is the difference. Composite blends wood fiber with plastic and protects it with a polymer cap. By the makers' own figures, Trex composite combines recycled plastic film with reclaimed sawdust, and TimberTech's composites are about 85% recycled content. PVC boards contain no wood: TimberTech's AZEK Advanced PVC is about 60% recycled material, all polymer.

How much of a composite board the cap covers varies. TimberTech's Edge boards are capped on three sides; its Pro boards, such as Reserve, are capped on four, including the grooves. Cut ends of any composite board expose the core, which is one reason end gaps and drainage under the deck still matter. A PVC board has no core to protect.

When composite is the better buy

For a typical raised deck with decent airflow, composite does the job for less. On 300 square feet, 2026 market ranges put composite at $11,000–$21,000 against $15,000–$26,000 for PVC, before railing and stairs.

• The deck is raised with open airflow underneath, so moisture is not a constant problem.
• Budget matters and you would rather spend the difference on railing, lighting or a cover.
• You want a particular color or grain that only a composite line offers.
• You are matching or extending an existing composite deck.

Our composite decks page and composite deck cost guide cover pricing and installation.

Weight is a minor factor on a new deck but matters on a re-deck. PVC boards weigh less than composite boards of the same size, so they are easier to carry up to a second-story deck and add less load to an existing frame. If you are putting new boards on an old structure, deck resurfacing starts by checking that the joists are sized and spaced for the board you pick, since PVC and composite lines each publish their own span limits.

When is PVC worth the premium?

PVC earns its price where moisture, fire or surface heat would push composite past its comfort zone. If none of those apply, composite is usually enough.

• Hot tub surrounds and pool edges, where boards stay wet and chemical splash is routine. See hot tub deck ideas.
• Low decks with little ventilation, where the underside stays damp.
• Foothills lots in Boise's wildfire overlay, where a Class A and Ignition Resistant board is a clear advantage.
• Sunny decks used barefoot, if TimberTech's cooler-touch claim holds up when you test samples yourself.
• Long ownership, where the limited lifetime product warranty is worth paying for.

One local wrinkle: Treasure Valley HOAs approve decking by product and color name, and composite and PVC collections use different color names even within one brand. Submit the exact collection and color you intend to buy, not a sample from a different line that looks close.

How do Boise's temperature swings affect each board?

Both move with temperature, and the install has to allow for it. Boise sees 108 freezing nights a year and about 55 days at 90°F or hotter, so a board laid on a cool April morning will be longer by August. PVC generally moves more along its length than wood-fiber composite, which is why PVC installation guides lean hard on end-gap tables and fastening near board ends.

In practice that means following the maker's gapping chart for the temperature on install day, using picture-frame borders to hide end joints and letting boards acclimate on site before cutting. Winter installs are possible for both; the footings, not the boards, are what slow cold-weather work here.

Fire ratings for Foothills homes

This is where PVC most clearly separates from composite. TimberTech publishes Class A flame spread (ASTM E84) and an Ignition Resistant designation (ASTM E2632) for AZEK Vintage and Landmark, and Class B with WUI compliance for Harvest. Trex markets Refuge, a PVC board, as ignition-resistant.

Some composites qualify too: TimberTech's Pro Reserve grooved board holds a California State Fire Marshal WUI listing valid through June 30, 2027, and Edge Premier is WUI compliant on square-shouldered boards only. Lots in the IR1 part of Boise's wildfire overlay come under Class 1 ignition-resistant construction rules; ask Boise Fire how those rules treat a deck surface before ordering.

Brand-by-brand details are in Trex vs TimberTech, and the Foothills wildfire decking guide covers the rest of the assembly.