Decking · Mixed

How a composite deck ages in Atlanta, GA

THE SHORT ANSWER

In Atlanta, composite won’t rot, but the damp still matters: about 123 rainy days and 76% average humidity mean shaded boards grow surface mildew unless they are washed once or twice a year. Model estimate: 24–31 years of service.

Main threat
Moisture & decay
Climate profile
Mixed
Expected life
24–31 yrs
Wash
Spring & fall
Rainy days / yr
123
Days ≥ 90 °F
54
Simulated composite deck in Atlanta, GA after 10 years
Year 10Surface mildew in shaded areas
MODEL SIMULATION
Atlanta, GA · capped composite boards, south-facing, full sun
Color lossModerate
Surface wearModerate
Mildew / rotModerate
Fails first hereShaded boards (surface mildew)

Storyboard

20 years in Atlanta, washed yearly

Composite deck in Atlanta, install: Install day
InstallInstall day
Composite deck in Atlanta, year 1: Slight early fade
Year 1Slight early fade
Composite deck in Atlanta, year 3: Slight early fade
Year 3Slight early fade
Composite deck in Atlanta, year 5: Color has lightened, then stabilizes
Year 5Color has lightened, then stabilizes
Composite deck in Atlanta, year 10: Surface mildew in shaded areas
Year 10Surface mildew in shaded areas
Composite deck in Atlanta, year 15: Surface mildew in shaded areas
Year 15Surface mildew in shaded areas
Composite deck in Atlanta, year 20: Surface mildew in shaded areas
Year 20Surface mildew in shaded areas

Atlanta’s wear fingerprint

Each bar is scaled to the highest of the 25 cities we cover; the black line marks the median.

Rainy days / yr123.4 · High
Avg humidity76.3% · Typical
Decay index79.5 · High
UV index (avg)1.3 · Typical
Freeze–thaw days51.5 · Typical
Days ≥ 90 °F54 · Typical

NOAA station ATLANTA FULTON CO AP (USW00003888, 12.8 km away), 1991–2020 normals · humidity & UV: NASA POWER.

What fails first here

  1. 1Early color fadeCapped boards lighten in the first 2–3 years, then level off. Stronger here than average: UV rank #15 of 25.
  2. 2Surface mildewComposite does not rot, but pollen and dirt on shaded boards feed mildew — common in Atlanta’s damp climate. A wash in spring and fall prevents it.
  3. 3Heat underfootAbout 54 days a year top 90 °F; dark composite can get uncomfortably hot in full sun. Lighter colors help.
  4. 4Gaps & fastenersBoards expand and contract with temperature — about 52 freeze–thaw days a year here; check hidden clips and end gaps every few years.

Upkeep

Atlanta maintenance calendar

Built from local normals: bar width is the share of days with rain; composite mainly needs washing.

Jan
FebWash & check for mildew
Mar
Apr
May
Jun
Jul
Aug
Sep
OctWash, clear gaps
Nov
Dec

Same city, other materials

How the alternatives age in Atlanta

Cedar deck in Atlanta at year 10 (simulation)
Cedar deck
Expected life here: 12–15 yrs · main threat: moisture & decay
See it age in Atlanta →
Wood fence in Atlanta at year 10 (simulation)
Wood fence
Expected life here: 11–15 yrs · main threat: moisture & decay
See it age in Atlanta →

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The 20-year storyboard as a tall pin, linking back to this page.

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Pinterest storyboard: composite deck in Atlanta, GA, new to year 20

Composite decks in similar climates

Nashville, TNCharleston, SCMobile, ALNew York, NYChicago, IL

…and in very different ones

Phoenix, AZLas Vegas, NVAlbuquerque, NMAll 25 cities →

Questions Atlanta owners ask

How long does a composite deck last in Atlanta?

Our model puts a capped composite deck at 24–31 years in Atlanta, 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 Atlanta?

Twice a year — in spring and fall. Atlanta’s damp climate makes mildew on shaded boards the most common complaint.

Is composite worth it over cedar in Atlanta?

In Atlanta our model gives untreated cedar 12–15 years and composite 24–31. In a damp climate that gap is mostly rot you avoid.

Why does wood turn gray or black in Atlanta?

Graying is UV plus weathering of the surface; black spots are usually mildew or algae feeding on that grayed layer in damp weather, not rot. A cleaner and a dry-season seal stop it.

Model simulation, not a guarantee: south-facing, full sun, no shade or ground-contact surprises. How it works.