Foam-Filled Dock Floats vs. Other Flotation Options
5 min reading time
The short answer
For most built-from-scratch or rebuilt floating docks, encapsulated foam-filled floats are a sensible default. The foam keeps providing lift even if the outer shell gets damaged, and the shell protects the foam from sun, water and debris.
Other options can make sense in the right situation, but each comes with a trade-off in cost, upkeep or what your lake allows. Here's how they compare.
How the options compare
The biggest differences are what happens when a float gets damaged and whether your lake allows that type of flotation.
| Option | Best for | If the outside is damaged | Main trade-off |
|---|---|---|---|
| Encapsulated foam-filled floats | New docks and full float replacements | The foam inside still provides lift | Costs more than improvised options |
| Air-filled plastic floats | Light handling or added buoyancy on an existing dock | Water can get in and reduce lift | Relies on a sealed shell |
| Plastic barrels | Small private projects, only where allowed | Water can get in and reduce lift | Used drums are banned on some waters |
| Bare or unencased foam | Generally not recommended | Foam is already exposed | Can break apart into the water, and it's restricted in some places |
| Modular plastic systems | Buyers who want float and deck as one system | Depends on the design | Less freedom to mix your own frame and decking |
A closer look at each option
Encapsulated foam-filled floats
These floats have a foam core sealed inside a hard plastic shell. Permafloat dock floats, for example, use a seamless, rotationally molded polyethylene shell with UV inhibitors, filled with EPS foam.
The main advantage is the backup. The shell protects the foam from sun, debris and wildlife, and the foam helps keep the float from sinking if the shell gets damaged. A damaged float should still be inspected and replaced when needed.
They also bolt directly to wood, steel and aluminum frames, and published buoyancy ratings make it easier to size your floats. Permafloat backs its current floats with a 15-year limited warranty.
Air-filled plastic floats
These are hollow, sealed plastic tanks. They're light and easy to handle, and they can be useful for adding lift to an existing dock.
The catch is that the air is doing all the work. If the shell or a fitting fails, water can get in and the float can lose lift. If you choose them, buy tanks made for marine use and include them in your regular inspections.
Plastic barrels
Barrels are a familiar low-cost option for small private docks, but savings can disappear if your lake doesn't allow them. Some lakes require flotation made for marine use and prohibit used drums, so check your local lake regulations before you buy.
Used drums can also bring practical problems, like leftover residue, unknown condition and no buoyancy rating to design around.
Bare or unencased foam
Exposed foam billets may look like a simple way to save money, but they're vulnerable to weather, waves and wildlife. As they break down, foam pieces can spread through the water and the float can lose lift.
Some lakes also restrict unencased foam or require it to be replaced, so check your local lake regulations.
Modular plastic systems
Modular docks combine float and deck in connected plastic sections. They can be a good fit if you want a complete system and aren't planning to build your own frame.
The trade-off is flexibility, because the system largely sets the look and layout options. A frame-and-float dock lets you choose your own frame, decking and float sizes.
What to check before you buy
Start with your lake's rules, because the best float is one you're allowed to install.
- Ask who manages your water. That could be a utility, a government agency or a local authority. You may need a permit to build or modify a dock.
- Confirm what flotation is allowed. Requirements vary, so check your local lake regulations. Some don't allow unwrapped foam or barrels that weren't designed as dock floats.
- Look for a published buoyancy rating. You need that number to size the dock. Our flotation calculator can help you work through it.
- Check how it mounts. Confirm the float can attach securely to your frame, with hardware rated for the water. Permafloat's mounting slots use 3/8" or larger galvanized or stainless fasteners.
- Compare the warranty. Look at the length and the exclusions, since overloading and ice damage are common limits.
- Think about fuel nearby. If flotation will sit near fuel lines or a fueling area, check your local lake regulations for extra requirements.
Dock flotation FAQ
Are foam-filled dock floats better than air-filled floats?
For most new docks, foam-filled floats are the safer choice because the foam can still provide lift if the shell is damaged. Air-filled floats are lighter and can work well for adding buoyancy, as long as they stay sealed.
Can I use plastic barrels for a floating dock?
It depends on your water. Some lakes prohibit used plastic and metal drums, so check your local lake regulations before you build.
Can I use Styrofoam for a floating dock?
Avoid bare foam. It can break apart and pollute the water, and it's being restricted in some places. If you want foam flotation, choose a float with the foam fully encased.
Do I have to replace old unencased foam right away?
That depends on your local lake regulations. Some lakes require unencased flotation to be replaced by a set date or once it's no longer serviceable, so ask your lake authority what applies.
Can I put foam-filled floats on my existing dock?
Usually, yes. Permafloat floats attach to new or existing wood, steel and aluminum frames. Check that the frame is sound and rerun your buoyancy numbers before you order.
Find the right float for your dock
Browse our Permafloat dock floats by size and depth, or use the flotation calculator to estimate how much buoyancy you need.
Need help choosing? Call us at 704-477-5470 or email info@shoreline-supply.com with your dock size and location.