How to Build a Seawall
A seawall can be a great addition to any waterfront property. It can not only hold back water and protect your landscape from erosion, but can also give your property a finished look. While a seawall is not difficult to build, it does take a lot of time and may require some heavy equipment. However, a basic seawall can be constructed over a few weekends.
The best time to build your seawall is in the autumn when the water level is at its lowest point. If you are building near a tidal area, try to at times of the day when the tide is out.
Before You Start
Research any permits or special codes and regulations you need to follow. This is important for many different agencies to make sure you do not do anything that will interfere with the ecological systems on or near the water.
Step 1 - Prepare Metal Pipes
The easiest way to build your seawall is to weld threaded rebar (bent into U-shape) to the metal rods to connect to the 2X10 pieces of lumber. You will need at least four per metal rod. You can either weld these yourself or take them to a metal shop.
Step 2 - Dig Holes
Mounting your metal pipes to the bottom of the lake bed might require you to use two heavy machines. Depending on the bottom, you might need a jackhammer to blast through the rock bed to go two feet into the bottom. Dig these holes every 8 feet for as long as you want the wall.
Step 3 - Pour Concrete and Set Poles
You might need to construct a water barrier to keep the hole dry long enough to pour the concrete. You can do this with a sump pump and a pail or wooded form. Place it around the hole and pump the water out. Pour the quick-drying concrete into the hole and set the post into it. The concrete should firm up quickly. Do this until all the metal poles are installed.
Step 4 - Install Lumber
Drill holes into the 2X10 treated lumber and install onto the threaded rebar. Do this along the entire length of the wall, working your way up to the top. Cut each piece of lumber to length, and then square up the ends with the circular saw.
Step 5 - Fill with Rocks
Fill in the land side of the seawall with rocks, then gravel, sand and finally topsoil. You can make this even with the top of the wall, or have some of the wall exposed for future seating or lighting.