By
eHow Home & Garden Editor
Difficulty: Moderately Challenging
Step1
Use Douglas fir wood for your deck structural elements. Pick out a different wood, perhaps pine, for your railings and exposed decking materials. Because Douglas fir is so strong, it requires puncture holes to enable preservatives and sealants to penetrate deep enough into the wood to do any good. Because of this, Douglas fir is not appropriate to use for railings and the exposed elements of your deck. Since Douglas fir is so strong, you can use it for any ledgers, beams and posts for your deck frame.
Step2
Puncture holes into the Douglas fir to protect the wood. Because the Douglas fir is such a strong wood, it doesn't easily absorb preservatives. You must make incisions to inject the preservatives deep into the wood.
Step3
Use about .40 pounds of chemical per cubic foot of wood to protect Douglas fir. If use this wood for above-ground parts of your deck, use a chemical with a .25 pcf rating.
Step4
Seal Douglas fir wood on top of the preservatives you are adding to it. You must paint, stain or seal this wood as soon as possible to protect it from the elements.
Step5
Understand that after you add the preservatives to the wood, it will appear dark green or nearly black if you are adding the .40 pcf preservatives. It will appear light green or tan if you add the .25 pcf.
