Species

• According to the Fisheries and Oceans Department of Canada, the best woods for building a dock are western red cedar, redwood, cypress and eastern white cedar, in that order. Permanent piles and dock cribs, on the other hand, should be made out of woods like Douglas fir, hemlock and tamarack because they’re stronger. Western larch, pine and spruce can also be used for permanent piles. Cedars, redwood and cypress are not only attractive, they’re rot-resistant and will last a long time. They require little maintenance and don’t need to be treated. As long as they’re used in fresh water, they can be allowed to turn naturally gray.
  
  

Cedar

• Western red cedar and Eastern white cedar are closely related woods. Both are lightweight, with a straight grain that’s easy to split. Cedar wood is easy to work with common woodworking tools. It doesn’t shrink much and is highly resistant to decay. One major difference between these two species is that Eastern white cedar is very knotty compared to Western red cedar, which has a clear wood. Western red cedar is also stronger than its eastern cousin.
  
  

Cypress

• Cypress wood has a close straight grain that resists splitting, cracking and warping. It’s easy to work with and is extremely resistant to weather, insects and fungus. Cypress logs are routinely harvested for their wood after lying in swamp water for decades. The wood is lightweight yet durable, and it doesn’t contain a lot of knots. An oil in the wood, called cypressine, acts as a natural preservative.
  
  

Redwood

• Redwood is a very durable wood that doesn’t shrink or swell much when exposed to water. Its resistance to decay and insects extends throughout the wood, not just on its surface, and it doesn’t tend to split or warp. Builders like to work with it because it doesn’t contain much pitch and is extremely easy to saw and nail. According to the US Department of Agriculture, it shrinks less than other common domestic softwoods.
  
  

Pressure-treated

• Marine borers often attack wood that comes into contact with seawater. Pressure-treating the wood with preservatives makes it resistant to borer attack and helps slow down decay. Using pressure-treated pine or spruce is about 20 to 30 percent cheaper than using cedars, redwood or cypress, but pressure-treated pine or spruce is also more likely to warp and crack. Check your local building codes before using pressure-treated woods because some cities and towns don’t allow it to be used in waterfront areas since it leaches dangerous chemicals into the environment.