Cedar Oils and Acids

• Cedar has natural oils and acids. These deter insects and help the wood retain an attractive appearance even after years in the weather. Those very oils and acids, however, can cause problems with nails or screws used to fasten fence boards to posts and rails. They will eat into the nail's protective coating, allowing water to enter and causing nails to rust. Paint or stain may delay the process, but most people prefer cedar fences unpainted.
  
  

Stains Reveal Problems

• The first sign of a nail problem on a cedar fence will be stains or steaks caused by rusty water in the fasteners. The only solution is to replace the fasteners, which means removing every nail or screw and installing a new one. If rusting nails are not replaced, they eventually will deteriorate to the point that they will no longer secure the fence boards.
  
  

Galvanizing Won't Solve the Problem

• Many homeowners think galvanized nails are immune to rust and corrosion, but this is not so. Galvanizing coats the nail with a layer of zinc, which does resist rust and corrosion better than steel. However, eventually, even zinc will deteriorate, allow water to penetrate to the steel -- and rust it. The process just takes a lot longer with good galvanized nails.
  
  

Aluminum or Stainless

• The recommended fastener for installing cedar fencing is aluminum nails. Aluminum nails will nor rust or corrode. The disadvantage is that they are somewhat more likely to bend when being pounded in. And they may be harder to find and more expensive than conventional steel nails. An alternative is stainless steel nails. These also will not rust, but are much more expensive and may be hard to find at standard building supply stores.