If you’re planning a DIY floating dock, the single most important choice you’ll make is what kind of floats will hold it up. Floats are the backbone of your dock — they determine its stability, safety, and lifespan. But not all floats are built the same, and picking the wrong type can sink your dock (literally).
Let’s break down the main dock float options you’ll see, and which ones are best for your DIY dock project.
1. Encapsulated Foam / Rotationally Molded HDPE Floats (The Industry Standard)
Encapsulated floats — sometimes called rotationally molded floats — are the gold standard for dock flotation. They’re made by rotationally molding a thick, UV-resistant polyethylene shell and filling it with closed-cell foam. The foam core keeps your dock buoyant even if the shell gets punctured, and the tough outer casing resists impacts, sun, and waves.
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Pros: Reliable, long-lasting, safe, and low-maintenance.
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Best For: All DIY docks, from small backyard builds to full-size boat slips.
👉 Why We Recommend Eagle Floats
Not all encapsulated floats are created equal. Eagle Floats stand out for:
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The strongest shell in the industry (better impact resistance than thin-walled alternatives).
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An industry-leading 15-year warranty (vs. 8–10 years for many brands).
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Unmatched foam core fusion for consistent buoyancy.
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Sizes for every application, so you can match floats to your dock design.
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Less hassle with repairs and replacements compared to cheaper options.
For DIY dock builders, that means fewer worries, longer dock life, and the confidence that your investment won’t fail a few years down the road.
2. Air-Filled Floats (or Lift Tanks)
Air-filled floats rely on nothing but trapped air for buoyancy. They’re hollow chambers, sometimes repurposed as lift tanks, and while they can work in some situations, they carry risks. A puncture, cracked seam, or slow leak can cause them to take on water and lose buoyancy fast.
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Pros: Lower cost, lighter weight, sometimes reused for lift applications.
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Cons: Vulnerable to leaks or punctures, less reliable long-term.
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Our Take: Some people view them as “okay” for short-term or budget builds, but for a DIY dock you want to last, we don’t recommend them.
3. Barrels
Using barrels as floats is one of the oldest DIY tricks in the book, but also one of the riskiest. Barrels can split, leak, or roll unpredictably, making them unstable and unsafe under load. What looks like a cheap solution often turns into costly repairs or a total rebuild.
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Pros: Cheap (or even free).
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Cons: Unstable, prone to leaks, short lifespan, unsafe.
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Bottom Line: Barrels aren’t a real solution for a long-lasting dock.
Sizing Floats for Your DIY Dock
No matter which quality floats you choose (encapsulated floats are the best bet), it’s important to calculate buoyancy correctly. Start by figuring out the weight of your dock frame, decking, hardware, and then add your live load (people, furniture, gear).
Buoyancy Needed Per Float = (Total Dock Weight + Live Load) ÷ Float Count
Of course, getting the right balance between float buoyancy and desired freeboard can be a nuanced activity. Our Dock Builder's Guide has more info on nailing down your float needs, and our DIY Kits make achieving target freeboard and live load support quick and easy.
Final Thoughts
For DIY dock builders, the takeaway is simple: don’t cut corners on flotation. Encapsulated foam floats, especially Eagle Floats, give you the strength, stability, and peace of mind to enjoy your dock for years. Air-filled floats may look like a budget option but carry real risks, while barrels simply don’t belong under a serious dock build.
If you’re ready to start your DIY project, check out our full line of dock floats or contact us for help planning your build.