Cypress is a conifer and a softwood. It grows in many foreign countries, but the majority of the domestic cypress is harvested in the Southeastern United States. Durability and natural resistance to wear and tear place cypress among the world's leading exterior building materials.
Live cypress trees love water. The natural tendency for cypress to flourish in or near water has provided cypress with a natural water resistance that makes it perfect for exterior use. Cypress trees produce an oily preservative known as cypressene. This natural oil provides cypress lumber with an innate resistance to the insects, moisture damage and decay that degrade other types of lumber. It's acceptable to allow cypress to age gracefully without any finishing products whatsoever, but most builders agree that regular maintenance adds longevity to cypress. Cypress is tough and durable, but direct contact with soil is never recommended.
Mold and Mildew
Cypress's love of water also provides a safe harbor for mold and mildew. The pesky, blotchy appearance of this nasty fungus is nothing new to cypress. Remove mold and mildew using a pressure washer on low setting. Apply a mild solution of bleach and water to the mold- and mildew-covered cypress. Allow it to remain on the wood for 15 minutes and wash it off, along with what's left of the mold and mildew. Allow the cypress to dry for at least a week before applying sealant.
Two basic milling processes typify cypress; rough-sawn and smooth-planed. Rough-sawn provides the rough texture that you see on exterior siding, trim, fencing or landscape elements. Clear or smooth planed takes the milling one step further, and smooths the surface to reveal a predominantly amber color, with reddish, olive or chocolate overtones. The dense, straight-grain texture and generally knot-free wood make smooth-planed cypress a great choice for outdoor furniture. Regular maintenance includes removing mold or mildew and applying a subsequent coat of natural oil, such as linseed oil. Allow it to remain on the surface for 15 minutes and wipe it off. Repeat every six months.
Refrain from using anything but stainless steel or hot-dipped galvanized fasteners with cypress. Other metals corrode and leave stain marks on cypress. If the cypress is dry, you can immediately proceed with a water-repellent sealer after the project is finished. Sealer will retain the natural honey color or yellowish hues of the cypress. If you want the cypress to acquire a weathered gray color, skip the sealer and allow it to age naturally. Most consumers prefer sealer or paint. If you choose paint, use only high-quality, 100-percent resin acrylic/latex paints after first using a primer. Use spray equipment if possible, spraying under boards, between and on the ends of boards. Regular maintenance includes another coat of sealer or paint every year or two. Water-repellent sealer with stain can be used to color cypress. When selecting sealers, choose one that contains a mildew repellent as well as a moisture inhibitor.