Decking · Hot & dry

How long does a pressure-treated deck last in Los Angeles, CA?

THE SHORT ANSWER

In Los Angeles, sun does most of the damage. UV here ranks #5 of 25 cities we cover, with about 26 days a year above 90 °F. Unsealed boards bleach to a pale silver and open up surface checks; with a decay index of only 8.5, rot is a slow, secondary risk. Model estimate: 12–15 years unsealed, 16–20 years sealed on schedule.

Main threat

Sun & UV

Climate profile

Hot & dry

Expected life (unsealed)

12–15 yrs

Fully gray by

Year 2

Best seal window

Jul – Aug

Sealed on schedule

16–20 yrs

Simulated pressure-treated deck in Los Angeles, CA after 10 years

Year 10Decay starting at board ends, deep checks

MODEL SIMULATION

Los Angeles, CA · treated southern pine boards, south-facing, full sun, no sealant

Drag through time 0 — 20 years

Color lossSevere

Surface checkingSevere

Mildew / rotModerate

Fails first hereBoard surfaces: checks, splits and cupping

Storyboard

20 years in Los Angeles, unsealed

Pressure-treated deck in Los Angeles, install: Fresh, green-tinted boards — **Install**Fresh, green-tinted boards

Pressure-treated deck in Los Angeles, year 1: Sun-bleached silver — **Year 1**Sun-bleached silver

Pressure-treated deck in Los Angeles, year 3: Checks and some warping — **Year 3**Checks and some warping

Pressure-treated deck in Los Angeles, year 5: Checks and some warping — **Year 5**Checks and some warping

Pressure-treated deck in Los Angeles, year 10: Decay starting at board ends, deep checks — **Year 10**Decay starting at board ends, deep checks

Pressure-treated deck in Los Angeles, year 15: Soft spots — probe for rot, deep checks — **Year 15**Soft spots — probe for rot, deep checks

Pressure-treated deck in Los Angeles, year 20: Soft spots — probe for rot, deep checks — **Year 20**Soft spots — probe for rot, deep checks

Los Angeles’s wear fingerprint

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

Rainy days / yr34.1 · Low

Avg humidity57.4% · Low

Decay index8.5 · Low

UV index (avg)1.5 · High

Freeze–thaw days0 · Low

Days ≥ 90 °F25.5 · Typical

NOAA station LOS ANGELES DOWNTOWN/USC (USW00093134, 5.5 km away), 1991–2020 normals · humidity & UV: NASA POWER.

What fails first here

1Checks, splits and warpingStrong UV (rank #5 of 25) dries and shrinks the surface faster than the core, opening fine cracks.
2Sun bleaching & raised grainSurface fibers break down under strong sun and wash away, leaving a pale, fuzzy texture.
3Rot at board ends & joistsSlow here (decay index 8.5), but ends and joists under planters still fail first.
4GrayingCosmetic, and fast: our model has the surface fully silver by year 2. Not damage on its own, but it means the protective surface is gone.

Upkeep

Los Angeles maintenance calendar

Built from local normals: bar width is the share of days with rain; sealant needs 2–3 dry days between 50 and 88 °F.

Jan

Feb

MarInspect ends & fasteners

Apr

May

Jun

JulSeal / stain

AugSeal / stain

Sep

Oct

Nov

Dec

Same city, other materials

How the alternatives age in Los Angeles

Cedar deck

Expected life here: 18–24 yrs · main threat: sun and UV

See it age in Los Angeles →

Composite deck

Expected life here: 23–30 yrs · main threat: sun and UV

See it age in Los Angeles →

Wood fence

Expected life here: 16–21 yrs · main threat: sun and UV

See it age in Los Angeles →

Vinyl fence

Expected life here: 22–29 yrs · main threat: sun and UV

See it age in Los Angeles →

Pin-ready

Save it for when you build.

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

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Pinterest storyboard: pressure-treated deck in Los Angeles, CA, new to year 20

Pressure-treated decks in similar climates

…and in very different ones

New Orleans, LA

Buffalo, NY

Miami, FL All 25 cities →

Questions Los Angeles owners ask

How long does a pressure-treated deck last in Los Angeles?

Our model puts it at 12–15 years unsealed and 16–20 years if it is sealed every 2–3 years. The national typical range is 10–15 yrs; Los Angeles’s sun and UV profile is why the local number differs.

When is the best time to seal a pressure-treated deck in Los Angeles?

July and August: the months with the fewest rainy days while average temperatures sit between 50 and 88 °F. Most sealants need 2–3 dry days to cure.

Cedar or pressure-treated: which lasts longer in Los Angeles?

Our model gives an unsealed pressure-treated deck 12–15 years here and untreated cedar 18–24 years. Where rot is slow, cedar’s stability wins: treated pine checks and warps faster in sun and frost.

Why does wood turn white or pale in Los Angeles?

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.