Framing & StructuralQuestion 366 of 700

Why must deck framing lumber in contact with the weather and near the ground be pressure-preservative-treated or naturally durable?

a.To resist decay and insect attack in the exposed, moist environment
b.To make it lighter
c.To improve its color
d.To make painting unnecessary

Explanation

Exterior deck lumber sits in a wet, exposed environment where untreated wood rots and is attacked by insects, so it must be preservative-treated or a naturally durable species to last. Treatment is not about reducing weight, improving color, or eliminating the option to paint or finish.

Law Reference: 2025 CA Residential Code §R507.2

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