What Can I Use to Waterproof Seasoned Cherrywood Siding?

Varnish

• Varnishes are clear finishes that coat the exterior surface of wood. Because varnish forms a hard protective layer over the wood, it keeps water out. However, varnish tends to crack and peel rather quickly, often breaking down after only a year or two. Fixing damaged varnish is somewhat difficult, and it requires the complete removal and reapplication of the varnish layer. Choose varnish as a waterproofing finish only with the awareness that it requires a good deal of maintenance.

Clear Water Repellents

• Clear water repellents contain a solvent, wax or another water repellent and a binding resin or oil. Water repellent preservatives also contain a fungicide to help prevent mildew problems. Water repellent preservatives sometimes also deter insects, which sometimes like to eat wood siding. Unlike varnishes, clear water repellents soak into the wood and become part of its surface. They are relatively easy to repair, and touch-ups just require a thorough cleaning and an extra coat of the water repellent.

Wood Toners and Semitransparent Stains

• Wood toners are water repellents with a tint to them. Semitransparent stains also soak into the surface of the wood, tinting and waterproofing it. The tint in wood toners and semitransparent stains provides more U.V. protection for the siding than clear sealers. Wood toners work over previously painted siding, while semitransparent stains work only after the user removes all old paint. Both are relatively easy to repair because they require touch-ups, rather than an entire refinishing project.

Paint

• Paints keep water off of wood siding, and their pigments also block damaging U.V. rays. Unfortunately, most paint does not prevent mildew growth. Before waterproofing with paint in an area prone to mildew, kill any existing mildew with bleach and look for special mildew-resistant primer and paint. Latex paints are relatively flexible and less prone to cracking than oil-based paints. Paints last longer than other finishes and can last for up to 10 years with a coat of primer and two coats of paint.

Solid-Color Stains

• Solid-color stains form a water-resistant coat over the surface of the wood, similar to paint or varnish. Solid-color stains have lots of opaque pigment, so they look similar to paints. Unfortunately, they can peel off of the siding like paint or varnish can, but they are easier to reapply than varnish. The U.S. Forest Service recommends solid-color stains, instead of paints, for wood that you may want to refinish or change the color of often. Remove old stains and sand away weathered wood before applying a solid-color stain to siding.