As a naturally porous material, wood is susceptible to moisture and can rot if overexposed. However, some species of wood are naturally moisture resistant and others can be treated to hold up well in rainy weather. Some of the most popular moisture-resistant lumber species include Iroko, teak, mahogany and Western Red Cedar. These are often used for outdoor furniture, cladding, fencing and timber-framed garden structures and construction.

The best woods for rainy weather also tend to be harder and more dense. This makes them sturdier and less prone to damage from storms. The strength of a wood is further enhanced by its growth history, which influences its density and durability. For instance, older trees have thicker trunks and branches, which are sturdier than thin and flexible ones. Likewise, hardwoods like Iroko and oak are stronger than softwoods such as pine.

The softer cedar also resists rot, mold and insects and is the preferred choice for shingle roofs, decks and dock planks. However, it can still swell and shrink in humid conditions so should be treated when it will be exposed to ground contact. Some woodworkers prefer to treat their cedar with polyurethane, which is a tough, cost-effective and durable sealant.