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Pacific Northwest Climate & Decking Challenges
The Pacific Northwest is defined by rain — 150+ days of precipitation per year in Seattle and Portland, with some coastal areas receiving over 100 inches annually. But PNW rain is often light and persistent rather than the intense downpours of the Southeast. This creates a constantly moist environment that promotes moss, algae, and mildew growth on outdoor surfaces.
Mild temperatures (rarely below freezing, rarely above 85°F) mean freeze-thaw is minimal, but constant moisture is relentless. Cedar — the traditional PNW choice — begins rotting within 8-12 years despite the mild temps. Composite decking becomes slippery and hosts mold in PNW moisture. Tropical hardwoods, evolved in rainforest conditions with far more moisture than Oregon or Washington, handle PNW rain with ease. Their natural density prevents moss from penetrating the surface, and their tight grain provides natural slip resistance.
Species Rankings for Pacific Northwest
BEST OVERALL
Ipe Decking in Pacific Northwest
Ipe is the premium PNW choice — its extreme density prevents moss and algae from penetrating the surface. The tight interlocking grain provides natural slip resistance in the rain. Ipe's natural oils repel moisture without any chemical treatment, and its Class A fire rating doesn't hurt in dry-season wildfire areas east of the Cascades.
BEST VALUE
Cumaru Decking in Pacific Northwest
Cumaru is the PNW's best-value option — 3,330 Janka handles constant rain at a better price than Ipe. Its natural oils repel moisture, and its density prevents moss penetration. At 30-40% less than Ipe, Cumaru makes premium hardwood accessible for PNW budgets.
TROPICAL FIT
Red Balau Decking in Pacific Northwest
Red Balau's SE Asian tropical origin means it evolved in rain-heavy conditions similar to the PNW. Its 2,700 Janka and natural moisture resistance make it a strong PNW performer at a competitive mid-range price. Warm red-brown tones complement PNW Craftsman and modern homes.
HEAVY DUTY
Massaranduba Decking in Pacific Northwest
Massaranduba's extreme density (67 lbs/ft³) handles PNW moisture with ease. Slight overkill for PNW's mild temperatures — the density that makes it a freeze-thaw champion in the Northeast is a luxury in the mild PNW. But if you want maximum longevity, it delivers.
BUDGET PICK
Garapa Decking in Pacific Northwest
The PNW's mild temperatures are actually Garapa's sweet spot — no extreme heat, cold, or UV to stress this lighter species. Garapa handles rain well and is the most affordable premium hardwood. This is one of the best climates for Garapa to truly shine.
Installation Adjustments for Pacific Northwest
Acclimation
10-14 days. PNW's high humidity means boards equilibrate relatively quickly. Cover boards to keep rain off during acclimation.
Board Spacing
3/16" gaps. PNW's consistent humidity means less seasonal expansion/contraction than drier climates.
Fasteners
316 stainless for coastal OR/WA (within 5 miles of ocean); 304 acceptable inland
Best Installation Timing
Best: June-September (PNW dry season). Spring and fall are possible but plan for rain delays.
Special Considerations
Ensure excellent ventilation under the deck — PNW moisture means mold can develop on the underside without airflow. Slope deck slightly for drainage. End-seal all cuts.
Pacific Northwest Maintenance Calendar
Spring
Full cleaning — moss and algae removal is the PNW's primary maintenance task. Power wash or scrub with deck cleaner. Oil if maintaining color (optional in low-UV PNW).
Summer
Enjoy the dry season. Spot-clean as needed. Best time for any repairs.
Fall
Second moss/algae cleaning before wet season. Clear leaves and debris to prevent moisture traps.
Winter
Let the rain do its thing — hardwood handles it. Check drainage. Remove any standing debris.
Oiling Frequency for Pacific Northwest
Oiling is truly optional in PNW — low UV means the wood silvers very slowly. 1x/year if you want to maintain color. Moss/algae cleaning 2x/year is more important than oiling.
Hardwood vs. Alternatives in Pacific Northwest
| Feature | Ipe Hardwood | Cedar | Trex Composite | Pressure-Treated |
|---|---|---|---|---|
| Lifespan in PNW | 75+ years | 8-12 years | 15-20 years | 10-15 years |
| Rain/Moisture Performance | Excellent — no absorption | Absorbs, rots | Molds, gets slippery | Absorbs, warps, rots |
| Moss/Algae Resistance | Surface only — easy clean | Penetrates deeply | Embeds in texture | Penetrates deeply |
| Slip Resistance (wet) | Excellent — natural grip | Moderate | Poor — very slippery | Moderate |
| Maintenance in PNW | 1-2 cleanings/year | Annual staining + cleaning | 2-3 cleanings + mold treatment | Annual staining + cleaning |
| 25-Year Total Cost | Lowest | Higher (2 replacements) | Similar | Higher (2+ replacements) |
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Hardwood Decking in Pacific Northwest — FAQ
Pickup Locations in Pacific Northwest
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About Ipe Wood
Species information
About Cumaru Wood
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About Tigerwood Wood
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About Garapa Wood
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About Massaranduba Wood
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About Red Balau Wood
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Hardwood Comparisons
Ipe vs composite, cedar & more
Ipe Deck Cost Guide
Installed cost per sq ft