Decking · Hot & humid
How a composite deck ages in Charleston, SC
In Charleston, sun is the main stress on a composite deck: UV ranks #13 of 25 cities we cover and there are about 25 days above 90 °F. Capped boards lighten noticeably in the first two years, then stabilize; dark colors also get hot underfoot. Model estimate: 24–31 years of service.
Storyboard
20 years in Charleston, washed yearly
Charleston’s wear fingerprint
Each bar is scaled to the highest of the 25 cities we cover; the black line marks the median.
NOAA station DWTN CHARLESTON (USW00013782, 0.8 km away), 1991–2020 normals · humidity & UV: NASA POWER.
What fails first here
- 1Early color fadeCapped boards lighten in the first 2–3 years, then level off. Stronger here than average: UV rank #13 of 25.
- 2Surface mildewComposite does not rot, but pollen and dirt on shaded boards feed mildew — common in Charleston’s damp climate. A wash in spring and fall prevents it.
- 3Heat underfootOnly about 25 days a year top 90 °F, so surface heat is rarely an issue.
- 4Gaps & fastenersBoards expand and contract with temperature; check hidden clips and end gaps every few years.
Upkeep
Charleston maintenance calendar
Built from local normals: bar width is the share of days with rain; composite mainly needs washing.
Same city, other materials
How the alternatives age in Charleston
Pin-ready
Save it for when you build.
The 20-year storyboard as a tall pin, linking back to this page.
Composite decks in similar climates
Atlanta, GA
San Francisco, CA
Nashville, TN
Mobile, AL
New York, NY…and in very different ones
Las Vegas, NV
Phoenix, AZ
Denver, COQuestions Charleston owners ask
How long does a composite deck last in Charleston?
Our model puts a capped composite deck at 24–31 years in Charleston, close to typical warranty terms. The boards outlast the look: expect some early fading and surface mildew in shade.
How often should you clean a composite deck in Charleston?
Twice a year — in spring and fall. Charleston’s damp climate makes mildew on shaded boards the most common complaint.
Is composite worth it over cedar in Charleston?
In Charleston our model gives untreated cedar 13–16 years and composite 24–31. The gap is smaller where rot is slow, so upkeep preference decides.
Why does wood turn white or pale in Charleston?
UV breaks down lignin at the surface; rain and wind wash the loose fibers away, leaving a bleached, silvery layer. It is cosmetic until checks open up.
Model simulation, not a guarantee: south-facing, full sun, no shade or ground-contact surprises. How it works.