The Importance of Using Wood Deck Sealers

Wood decks can be beautiful additions to any home. However, continuous exposure to extreme weather conditions will eventually lead to various deck problems like cracks, raised grains, wood decay and fungal growth. To prevent these problems, proper care and maintenance like applying stains, sealers and other finishes to the wood deck will enhance their longevity and durability.

Depending on the way they work on wood, wood deck sealants can be broadly categorized into Water Repellants (WR) and Water Repellant Preservatives (WRP). A Water Repellant Preservative is basically a Water Repellant added with mildewcide or preservative.

Types of Sealants

Several types of sealants include the following:

1. Open Finishes - These type of sealants are considered as soft with minimal surface build, thus providing limited or no protection from wear, water or chemical absorption. While they allow absorbed moisture to escape, they are not spill-resistant. Open finishes are the least expensive and least effective sealants, which are purely "color coats" composed of 90% water plus color and binder to hold it together. An example of open finish is Latex Semi-Transparent Stain.

2. Closed Finishes - These sealants are water repellent and chemical resistant, but have closed upper surfaces that trap moisture, which lead to wood decay. Therefore, they are not really suited for exposed wood like decks and sidings. Closed finishes are not elastic, and are usually hard and glossy. They also do not penetrate effectively, which causes the surface to loosen. Varnish and Polyurethane examples of closed finishes.

3. Microporous - Considered as the perfect finishes, these sealants help in long-term wood preservation. Also known as penetrating sealers, they allow the wood to breathe and allow moisture to escape beneath the wood surface. Acrylic Blends is an example of a microporous sealant.

Sealant Tips

Even though they are long lasting and economical to produce, using clear liquid sealants for the exteriors should be avoided, since they are completely closed, irremovable or over-coated, and allow mildew to grow below the wood surface. When buying sealers, pay close attention to the contents printed on the product labels. Most advertised wood sealers are composed of 95% mineral spirits and 5% alkyd resin. Since sealers with only 5-10% solid content are not very long lasting, it is recommended to get a sealer with good quality high resin content.