Why Wood Choice Matters (and Why Cedar Wins)

In this guide, we’ll explain:
✔ what causes wood rot outdoors
✔ why Western Red Cedar naturally performs better
✔ how to prevent decay and maintain your structure
✔ the best finishes for long-term protection

What Causes Wood Decay and Degradation?

Wood decay is caused when fungi break down the cellular structure of timber. For these fungi to survive, they need moisture, oxygen, moderate temperatures, a food source (wood itself).

Once active, decay fungi can weaken wood fibers, cause color changes, create softness, lead to cracks, checking, and structural instability.

Wood degradation also includes non-fungal damage such as UV exposure, weathering, insects, fire.

Together, these elements speed up wear and reduce a structure’s lifespan.

Why Western Red Cedar Holds Up Better

Western Red Cedar is one of the top-performing woods for outdoor structures due to its:

1. Natural resistance to rot, decay, and insects
2. Low density and inbuilt air pockets that reduce moisture retention
3. Exceptional dimensional stability (less warping, less movement)
4. Low-maintenance surface
5. Long lifespan even when exposed to the elements

Because of its natural durability, cedar is commonly used for sheds, pergolas, greenhouses, garden beds, playhouses, and outdoor furniture. 

If you want longevity with minimal upkeep, Western Red Cedar is one of the best choices.

How to Prevent Wood Decay in Outdoor Structures

1. Start With the Right Wood

Using durable species like Western Red Cedar (Thuja plicata) is a promising long-term solution. It naturally resists decay without relying on chemical preservatives.

Pressure-treated lumber offers some protection, but moisture control is still essential — preservatives alone can’t stop water absorption.

2. Control Moisture Exposure

3. Stop Rot From Spreading

If you notice rot:

1. Identify the moisture source

2. Dry the area

3. Cut away or treat affected wood

4. Apply a fungicide or protective finish

Early treatment prevents it from spreading into nearby components.

4. Paint or Stain for Added Protection

Opaque paints provide strong weather protection thanks to high pigment content. They’re best applied in a factory setting for a smooth, long-lasting finish.

If painting onsite:

1. Prime first
2. Apply a durable topcoat
3. Ensure the surface moisture content is under 16%

5. Choose Oils or Clear Finishes Carefully

Clear varnish or unpigmented oils can protect wood while showcasing its natural grain — but they generally:

1. Have very low UV protection
2. Require more frequent maintenance
3. Should not contain wax if you plan to paint later

Always check with a qualified retailer for the right product choice.

6. Use Wood Stains for Added Protection

Wood stains:

1. Protect against weather
2. Enhance wood character
3. Require re-application every few years

They’re a great middle-ground option if you want both aesthetics and durability.

7. Consider Translucent Coatings

These give a paint-like film while still showing wood grain.

Re-apply as needed (location-dependent) to keep the structure protected and looking new.

The Best Finishes for Outdoor Wood

Here’s a quick summary of common finishing options: