Generally, it is not recommended to use non-pressure treated common boards for exterior structures. While there are exceptions, typical untreated lumber lacks the necessary resistance to withstand outdoor conditions.
Why Common Boards Aren't Recommended for Outdoor Use
As a rule, it is not recommended to use non-pressure treated wood for exterior structures, according to wood experts. Common boards, often made from species like pine or fir that haven't undergone pressure treatment or don't have natural resistance, are susceptible to:
- Moisture Damage: They easily absorb water, leading to swelling, warping, and cracking.
- Fungal Decay: Exposure to moisture promotes the growth of fungi, causing rot and weakening the wood structure.
- Insect Infestation: Untreated wood is an attractive target for pests like termites and carpenter ants.
These issues can significantly shorten the lifespan of an outdoor structure and compromise its safety and appearance.
Exceptions: Woods Naturally Suitable for Outdoors
While non-pressure treated wood is generally discouraged for exterior use, the reference highlights that there are exceptions among certain wood species known for their natural durability.
Three commonly-used species of wood used in exterior applications that possess natural resistance include:
- Cedar: Known for its aromatic oils that repel insects and resist decay.
- Redwood: Similar to cedar, redwood contains natural compounds that make it resistant to rot and insects.
- IPE (Brazilian Walnut): An extremely dense hardwood that is highly resistant to decay, insects, and wear, often used for decking and outdoor furniture.
Each of these species carry some natural resistance to weathering when exposed to sun and moisture, making them suitable alternatives to pressure-treated lumber or non-durable common boards for certain outdoor applications.
Choosing the Right Wood for Exterior Projects
Selecting the appropriate wood is crucial for the longevity and performance of any outdoor project.
| Wood Type | Suitability for Exterior Use (Untreated) | Key Characteristic (Reference-Based) |
|---|---|---|
| Common Non-Treated Boards | Not Recommended | Low resistance to weathering |
| Cedar | Recommended (Exception) | Natural resistance to weathering |
| Redwood | Recommended (Exception) | Natural resistance to weathering |
| IPE | Recommended (Exception) | Natural resistance to weathering |
| Pressure-Treated Lumber | Recommended | Chemically treated for decay/insect resistance |
Note: While the reference focuses on naturally resistant woods, pressure-treated lumber is also a widely used and recommended option for exterior structural applications.
For most exterior projects requiring durability against the elements, choosing pressure-treated lumber or naturally resistant species like cedar, redwood, or IPE is the recommended approach over using common, non-treated boards.
