It is common to use a treated wood post as a support in a structure, but sometimes treated wood posts are not attractive and do not match the rest of the project. There are several easy ways to cover the post. The way that this article will focus on is to cover a treated wood post with a casing of non-treated lumber. Another way not covered in this article is to use PVC post sleeves which are sold at most lumberyards. These simply slide on the post and require no additional work.
How to cover a treated post.
First, select the proper size boards. For example, lets say you are working with a 4x4 post (for which the actual dimensions are 3.5 inches square) that has 6 feet exposed. In order to cover the post, you will need to cover the 3.5 inches of the post and the thickness of the other boards. You generally will use a 1x board (actual thickness ¾ of an inch). So, the width of the boards will need to be 4.25 inches, for which the most common board size available would be a 1x6.
Next, cut the board to the required dimensions. For our example above, you would need (4) 6-foot-long boards that are 4.25 inches wide. Using the table saw, rip the boards lengthwise to the 4.25 inches width. Then, cut them to the appropriate length (in this case, 6 feet). You should now have 4 boards that are 6 feet long by 4.25 inches wide.
Finally, fasten the boards to the post. Start on one side and place the first board flush with one edge of the post, and screw or nail the board to the post. Going around the post, place the next board on the next of each of the 4 sides. Each of the remaining 3 boards will cover not only the post, but also the exposed edge of the board previously installed.