Prevent Damage from Rusting Steel Post Bases
This past week we looked at the same post that we show here below. Last week though, we looked at the tops or heads of these posts. Today we’ll look at the foot or the base of these posts, instead. There are completely different issues to be discussed as the discussion applies to the base of the post. The header of these posts carry the girder above which then connects to the individual joists of the roof. This configuration or assembly and respective connections are exactly the same as you would find in a typical deck installation. Here though, it’s just a rooftop installed over a concrete patio.
The base of one of these posts is shown below in the next picture. Based on the cutting at the edges of the penetration through the slab, it looks like this concrete has been cut, after its initial installation, to allow the post base to pass through. At that point, it’s likely that the post-based is set into a concrete footing. Concrete footings are required to stabilize and secure almost all types of deck posts. Here in this patio, even though it’s not a deck, this area of construction also applies the same way as it would in a backyard deck.
The picture below shows the rusting at the base of the post.
Instead of setting the post bases through concrete, they can also be attached at the top of the concrete slab. That type of method might be better. We can see points or details of arguments for both differing approaches, but we would generally recommend installing the post on top of the concrete slab but not just in contact with the slab. Instead of being in contact with the slab, a post base hardware tie can be installed to elevate the bottom of the post just above the height of the concrete. By being separated from the concrete it allows the post to avoid the majority of moisture wicking, over its lifespan.
Even though most types of concrete are made with portland cement, they still have a degree of permeability. Portland cement is known for its ability to resist moisture. It’s still permeable though. In some cases, the resistance to moisture can help extend the life of a concrete slab and associated building elements. The reason for concrete porosity though is that molecules of gas created during the concrete curing process will, in some cases, leave a cellular framework that moisture can pass through.
Here, the risk of moisture is more related to wicking away from the concrete, but still lacks the permeability found in many organic materials. Here instead the problem is not related to wicking, it’s actually related to water pooling or collecting around the base of the posts. Even though the patio is covered with a rooftop which extends beyond the location of the post, the area around the edge of the slab can still get wet. Many of the typical rain cycles in our region have rains that fall relatively straight in line to the surface of the earth. In other cases though, rains can be at least slightly wind driven.
As rain lands on the adjacent areas outside of the roof, there’s generally a degree of splash back which can hydrate or simply get an area of a slab like this wet. That cycle of weather repeats, many times throughout a typical year. In this particular case, as you can see in the picture below, there is a void around the edge of the post.
That area can become significantly hydrated. When that area becomes hydrated, it can trap moisture against the face of the post. Even though many types of paints can resist water infiltration, they generally don’t resist it indefinitely nor completely. Many paints have even just a slight degree of permeability and can deteriorate significantly through long or repeat cycles of precipitation.
Here as water has built up around the base of the slab, particularly since the area of excavation is depressed or suppressed around the post, it has built up and stayed wet for longer than ideal durations. That residual exposure to excessive moisture has led the paint to deteriorate which then has allowed the steel to oxidize.
Without a treatment of repair and preservation, these still post will oxidize very quickly, in a time of period of time much shorter than their intended lifespan.
Use a contractor who understands and cares about doing things right. Always, feel free to reach out to us here at Dupont Decks and Patios. We are happy to help with almost all steps of the deck building and design process. A backyard and outdoor space should make a significant, positive impact on both quality of life and home value. We can help with more than just decks, we also build patios, pergolas, ramadas, awnings, gazebos, arbors, and privacy fences.
Let us know about your ideas and talk to us if you have questions about possibilities. We are happy to participate in improving your outdoor space and quality of life! You can call us at (202) 774-9128. You can find us online at https://dupontdeckspatiosdc.com and you can email us there as well at https://dupontdeckspatiosdc.com/contact-us
