As a Seattle home inspector, I get the opportunity to see a lot of posts in crawl spaces and basements and under decks. There are usually no issues in newer properties. The posts generally are centered on large concrete piers with connections at the concrete pier and at the beam. In addition, there is usually a tarpaper or asphalt barrier between the bottom of the post and the concrete.
As the photos above show, the posts are well above the ground and properly supported with positive connections. This configuration is what I want to see, and with newer construction, I don’t encounter many issues. On the other hand, in older homes in the Seattle and outlying areas, I find many problems – typically in crawl spaces where there is limited access that makes installing posts difficult.
As I crawl the area, I check for connections and usually do not see any. I give the post a light push, and too often the post comes loose. I encounter other issues like posts in direct contact with the soil or at ground level where they are wicking moisture from the concrete and causing rot. Keep in mind that the farther the post is elevated away from the soil, the better. The clearance reduces, or eliminates altogether, the chance of the wood wicking moisture.
Other conditions I find are posts that are out of level and with multiple shims (small pieces of wood that are used to close gaps in the connection). My opinion regarding shims is to use them as little as possible. If the post is cut to the proper length, no shimming will be necessary.
If new posts are to be installed on older property, they should include a solid poured concrete base or prefabricated pier, positive connections at the top and bottom, and a moisture barrier between the concrete and the wood. It is actually very basic work that should not be difficult to accomplish. Most of the time it is the lack of access and working in tight quarters that makes installation tough.
It’s important to remember that posts are structural members that support significant house loads. So if you’re going to attempt to work on structural components, I advise you to consult with a professional contractor.
I’ve included photos below that illustrate some of the conditions I routinely report on in older homes.
Shimmed post with an undersized pier Shimmed post. Post that is on the edge of the pier with no
& no vapor barrier. connection.
Shimmed post. Rotting post too close to the earth. Post wicking water from the concrete/rotting.