Cedar is a common wood for building outdoor furniture. Cedar withstands the elements well, making it a long-lasting wood for most outdoor projects. Insects don't like its aromatic scent, which is why it is also a popular choice for indoor furniture and blanket chests. Western Red Cedar is the most common type available in lumberyards. Other types are Northern White Cedar and Eastern White Cedar.
Cypress is another long-lasting, tough wood for building outdoor furniture. Cypress is not only resistant to decay but also resists twisting and warping. Most of the cypress available is grown in the southeastern United States. Because cypress doesn't contain much sap, it paints and stains well.
Teak wood is a good choice for building outdoor furniture, especially benches, chairs and patio sets. Because it contains natural oils, it does not need to be stained or painted. Teak is a tropical wood that is grown primarily in Indonesia. As a result, it can be expensive. Decide if the cost outweighs the low maintenance of your finished project. A somewhat lower cost alternative is shorea, another tropical wood.
Although Brazilian cherry is used mostly in high-end indoor flooring, the lumber can also be used for building outdoor furniture. It is not as insect and disease resistant as the previous woods listed and its cost is relatively high.
Perhaps the most popular choice of wood for outdoor furniture is pressure-treated pine. One reason for this is the low cost. It is the least expensive choice for not only your patio furniture or Adirondack chairs, but is used to build decks, pool enclosures, trellises, arbors and other outdoor structures. You will find a wide selection of pressure-treated wood at your local lumberyard.