Buying a waterfront home requires diligence in knowing all aspects of home ownership prior to purchase. Some homes come with seawalls others may just have a mangrove shoreline. Same goes for those considering building on a vacant waterfront lot. Regardless of whether you are looking for a sailboat accessible home/lot or properties that have a passageway to open water via a bridge the mechanics of building a seawall are the same.
Many neighborhoods in Punta Gorda have seawalls in place which are owned by the city and maintained by the city. The rest of Charlotte County including Port Charlotte you are responsible for the maintenance of your waters edge. With that said if you are buying a property with an existing seawall: Be Careful! Most homeowners and realtors don’t understand the mechanics of seawall failure and the tell-tale signs of what to be concerned about. A new seawall will likely cost between $25,000 and $35,000 depending on how long the seawall, how deep the seawall panels are and any other factors such as blasting rock if necessary to allow the seawalls to be put in place. Deeper waters for sailboat properties may require a seawall that is placed deeper into the canal which requires a longer seawall form, which adds cost. Most canal bottoms are mud so putting them is place is not hard.
A seawall is built by placing pre-cast concrete panels (see pictures below) that are rectangular in shape into the bottom of the canal. These panels when cast have multiple loops of heavy rebarb that a crane can hook onto BUT also serve as a mechanical device to attach the top cap to a rod that ties back into the lot (more on that later). Each panel is lifted into place with a crane and generally 2-3 men stand in the water (yes, very dangerous job) and physically manipulate them into position while shooting a jet of water into the mud bottom blowing the mud out of the way as the panel is pushed further into the canal bottom. Each panel is Tongue & Groove, like a hardwood floor. Once all panels are positioned to the length of the property, weeks or months are allowed for the seawall to “settle in” prior to the next steps.
The second phase of seawall installation is to build the forms for the top cap. As previously mentioned these forms have a loop of rebarb (see photo with orange paint on rebarb). Once the forms are in place a long piece of heavy rebarb with a hook on the end is connected to the loop of rebarb that is on top of the seawall panel. When the concrete is poured into the form the rebarb tie-back is permanently attached and embedded into the concrete. This is the big stabilizer to your seawall! The rebarb is then angled down into the soil where it is attached to a block of concrete reinforced with rebarb. This concrete tie down is known as a Deadman (see pictures). I think the pictures below will tell the whole story. Seawalls are not very complicated but extremely labor intensive to install.
After all the concrete hardens earth is put back into place and now your are ready for dock and boat lift installation.
As for maintenance, there is really not much for you to do to a seawall. The only maintenance is when some of the material on the land side develops a hollow spot. This usually forms during our rainy season when soil and marl (crushed coral) are washed out. You can by marl, which compacts like concrete once installed and is used to fill the holes. If the pockets behind the seawall become very large (like big enough for someone to climb into) the water/land pressure can exceed the static pressure on the water side and cause lateral fractures to your seawall which may lead to your seawall falling down the road. Don’t worry however as simple maintenance will prevent this from happening.
I am here to help when looking for that dream property to place your sailboat or power boat behind. There is nothing quite like having your boat at your own dock! Be sure of your seawall condition even if it is a city owned seawall. Of course, I can help you with understanding the condition of a seawall on any property
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The Hook (inside cap from)that will have rod tiebacks connected 
Seawall Cap Form, prior to concrete poured in.
