Importance

• Over time, exposed exterior wood will change into a weathered gray. In addition, consistent exposure to moisture can lead wood to rot and warp. Unless you want to pay hundreds to thousands of dollars over the years in maintenance costs, seal your wood deck with the proper coating.
  
  

Polyurethane Sealers

• Water- and solvent-based polyurethane sealers are well-suited for protecting interior wood surfaces from moisture and abrasion. While also effective at protecting wood decks in the short term, these coatings eventually tend to fade, peel and flake. If you choose to seal your wood deck with a clear wood sealer, expect to have to refinish it each year.
  
  

Stains

• Water-resistant stains are well-suited for wood decks. Not only do they enhance the appearance of the wood, they permeate its surface and saturate the interior fibers. This goes a long way toward preserving the wood's life. Stained wood also eventually requires refinishing; however, stained finishes tend to last two to four times as long as a clear wood sealer.
  
  

Application

• Apply oil-based stains and solvent-based sealers using a natural-bristled paintbrush. Don't use synthetic brushes unless you are working with water-based coatings. You can also use a roller equipped with a foam cover to apply polyurethane sealers. For best results, roll along with the wood grain. Never apply stain or sealer in temperatures below 45 degrees Fahrenheit. Be sure to rinse the deck before beginning the application process. Use a pressure washer equipped with a wide-angle tip.
  
  

Considerations

• Before you apply a water-resistant stain to your wood deck, determine exactly what type of wood it is made of. If the deck is made of pine, fir or another type of softwood, any liquid oil stain will do. If the deck is made of oak, maple or another type of hardwood, it requires a different type of stain. Hardwood decks are too dense to absorb liquid stains. Unless you want a splotchy finish, apply a slow-absorbing oil-based gel stain.