Composite or wood decks in salt air
Composite or wood is the main question people ask here, and each side gives something up. Here is what salt air, sun, and mold mean for each, and what the cost guide shows for both.
What each one costs
Wood costs less up front.
Installed, our deck cost guide estimates $4,300 to $12,700 for a new pressure-treated wood deck of typical size and $25 to $54 per sq ft for a new composite deck. Entry-level composite costs less than premium lines or PVC. These are estimates, not quotes.
Salt air and hardware
Near salt water, the screws and hardware matter for either one. Trex calls for its recommended stainless steel screws in any area near saltwater, and Simpson Strong-Tie rates Type 316 stainless as more corrosion-resistant than Type 304 in salty coastal air.
Salt spray drops off sharply between 300 and 3,000 feet from the shoreline, so we ask how close you are. In neighborhoods that back up to salt marsh, like many in Mount Pleasant, the screws and connectors matter as much as the boards. Farther inland, as in Summerville, code-approved galvanized hardware usually does the job.
Heat, mold, and upkeep
Composite skips the staining, sealing, and sanding that wood needs, and it doesn't splinter. It does get hot in full sun. Trex warns against long skin contact on hot, sunny days, and darker colors feel hotter. If the deck sits in full sun, a lighter color or some shade helps.
Composite can still grow mold. Trex says its boards aren't food for mold, but dirt and pollen on the surface are, and mold needs moisture to grow. It doesn't hurt the boards structurally. Trex recommends cleaning twice a year, for example in spring and fall.
The frame underneath
The frame under a composite deck is usually still wood, so the framing details matter just as much. Lumber that touches soil has to be rated for ground contact, posts get their cut ends treated on site, and joists are spaced to the board maker's chart. We gap composite boards per the maker for drainage and expansion and leave open space under the deck for airflow.
A sound frame also opens a cheaper option. If the posts, beams, joists, ledger, and hardware are sound, new boards and railings on the old frame cost far less than a rebuild. Our deck replacement page covers how we check.
How to decide
It depends on what you'd rather pay for: a lower price up front with wood, or less upkeep with composite. At the quote we can price wood alongside composite and bring board samples so you can see the colors in your light. See composite decks and custom wood decks for what each job includes.
Questions homeowners ask
Is composite better than wood in Charleston?
It depends on what you'd rather pay for. Wood costs less up front. Composite skips the staining and sanding, gets hotter in full sun, and still needs cleaning.
Do I need stainless steel screws?
Near salt water, yes. Trex calls for stainless steel screws near saltwater. Salt spray drops off sharply between 300 and 3,000 feet from the shoreline, so distance matters.
Does composite get moldy?
It can. Dirt and pollen on the surface feed mold when there's moisture. It doesn't hurt the boards structurally, and cleaning twice a year helps.