Dock Floats: Types, Buoyancy and How Many Your Dock Needs

This article contains affiliate links: if you buy through them we may earn a commission, at no extra cost to you. Read our affiliate disclosure.

Late in the season, a lake neighbor walks out to the end of his floating dock with a cooler and two grandkids, and the far corner dips until water runs over the boards. Nothing broke. One of the dock floats underneath has slowly lost its lift, and the dock is telling him. Dock floats are the plain black boxes that hold up almost every non-inflatable floating dock in the US, and choosing, sizing and replacing them is mostly a matter of reading the right numbers. This guide covers the types, the buoyancy figures makers actually publish, how to work out how many you need, and the rules on bare foam that many lakes now enforce.

In short: most floating dock floats today are encapsulated: a rotomolded polyethylene shell filled with EPS foam, rated by the maker in pounds of buoyancy (for example 600 lb for a Taylor Made 24 x 48 x 16 in float, 2,475 lb for a Barr Plastics 48 x 96 x 16 in float). Add up the dock’s dead load and the live load you expect, divide by the float rating, and leave a healthy margin, because those ratings assume the float is fully under water. Bare foam and used drums are banned or restricted on many US waters, so check local rules first.

What dock floats do, and what freeboard means

A float holds up a dock the same way a boat hull does: it pushes water aside, and the water pushes back with a force equal to the weight of the water displaced. Fresh water weighs about 62.4 lb per cubic foot (USGS), so every cubic foot of float pushed under can carry roughly that much, minus the float’s own weight. That is why makers quote buoyancy, and why the numbers track the size of the float so closely. Barr Plastics, a float maker, notes that its ratings assume the float is fully submerged, and adds that dock floats are not designed to be fully submerged. Treat the rating as a ceiling, not a working load.

Freeboard is the height of the deck above the water. Bellingham Marine, a marina builder, gives a handy rule: in salt water, 5 lb of load on one square foot of a floating object sinks it about 1 inch. Barr recommends 12 to 14 in of freeboard for most residential docks, counting the frame and decking. Low docks are easier for kayaks, but every inch of float you sink to get there is lift you no longer have for people.

Types of floating dock floats

Type	What it is	Good to know
Encapsulated foam floats	Seamless polyethylene shell filled with EPS foam, with a flat top and mounting slots	The standard choice today; the foam keeps the float up if the shell is holed (Taylor Made)
Bare (unencapsulated) foam	Blocks of polystyrene bolted under the frame with no shell	Breaks into beads and litter; banned or being phased out on many waters (see below)
Air-filled plastic floats	Hollow rotomolded polyethylene drums with no foam inside	No foam to shed; a hole can let water in, so they depend on the shell staying sound
Barrels and drums	Re-used plastic or metal drums strapped to a frame	Cheap but restricted: TVA prohibits previously used drums for flotation
Modular cubes and sections	The float is the deck: plastic cubes or sections that lock together	No separate floats to size; see modular docks

Encapsulated dock floats

Encapsulated dock floats are what you will find at marine dealers and on Amazon. Taylor Made describes a seamless, UV-resistant black polyethylene shell filled with EPS foam, which protects the foam from salt water, gasoline and most chemicals, plus a thick mounting flange you drill for fasteners. Barr Plastics describes a one-piece rotomolded shell of virgin polyethylene with UV inhibitors around EPS foam, and Eagle Float a seamless one-piece virgin polyethylene shell with a 0.15 in nominal wall and a solid EPS core; both have mounting slots molded into the flat top. Because the foam fills the shell, a puncture does not sink the float the way it can an empty one.

Foam dock floats without a shell

Older docks often sit on bare white foam billets. They float well when new, but sun, waves, boats, ice and animals break the surface into beads that end up in the water. That is the reason many authorities now restrict them:

• Tennessee Valley Authority (TVA) lakes. Federal rule 18 CFR 1304.400 prohibits using or reusing unencased flotation for repairs, replacement or new construction, and requires existing unencased flotation to be removed and replaced by December 31, 2031. Flotation must be commercially manufactured for marine use and must not crack, peel, fragment, become waterlogged or lose beads.
• Vermont. Since July 1, 2024, polystyrene foam used as flotation in Vermont waters must be encapsulated, with a covering expected to last at least 10 years. The state’s Department of Environmental Conservation says garbage bags, shrink wrap, hardware cloth and plywood do not count.
• Lake of the Ozarks, Missouri. Ameren, which manages the lake, banned new non-encapsulated foam in 1995 and set December 31, 2008 as the final deadline to replace it, calling broken foam the largest source of man-made debris in the lake.

Rules differ by state, lake authority and reservoir operator, and these are only the ones we confirmed. Before you buy or rebuild, check our permits and local rules guide and ask whoever manages your water.

Plastic air-filled floats

Some makers sell the same rotomolded shell empty. Dock Edge+, for example, lists its 2 x 4 ft x 8 in float in both a foamed and an empty version, each with a stated flotation of 260 lb. Vermont’s environmental agency calls air flotation the more environmentally friendly option, since there is no foam to shed if the shell is breached. The trade-off is that the shell is the only thing keeping water out. Plastic dock systems such as EZ Dock skip separate floats entirely: their polyethylene sections have open pylons underneath, are 15 in high and draw about 1 1/2 to 2 in of water, according to EZ Dock’s FAQ.

Barrels and drums

Plastic drums on a wooden frame are the classic budget dock. They work, but used drums carry real risks. TVA’s rule prohibits plastic, metal or other previously used drums or containers for flotation, citing the possible release of toxic or polluting substances and the navigation hazard of metal drums that partly fill with water and break loose. Illinois’s statewide permit for minor docks allows metal drums only if they are foam-filled. If you are set on drums, use new, clean, purpose-made floats where your rules allow them, and never a container that held chemicals or fuel.

Modular cube docks

With cube docks the floats are the dock. Candock’s G2 cube is 19 x 19 in and 14 in high, air-filled HDPE, with a stated buoyancy of about 150 lb per cube, or about 60 lb per square foot. You add cubes rather than floats to carry more. More on these in our modular docks guide.

Dock float sizes and buoyancy, as makers state them

Floats come in a handful of standard footprints (24 x 36, 24 x 48, 36 x 48, 48 x 48 and 48 x 96 in are common) and heights from about 8 to 32 in. Taller floats give more lift on the same footprint. These are the published figures we found:

Maker and float	Size (W x L x H)	Stated buoyancy
Dock Edge+ (foamed or empty)	24 x 48 x 8 in	260 lb
Eagle Float	2 ft x 4 ft x 12 in	390 lb
Taylor Made 46118	24 x 36 x 12 in	335 lb (approx.)
Taylor Made 46116	24 x 48 x 12 in	450 lb (approx.)
Taylor Made 46117	24 x 48 x 16 in	600 lb (approx.)
Barr Plastics BD2448-16	24 x 48 x 16 in	598 lb
Taylor Made 484816	48 x 48 x 16 in	1,200 lb (approx.)
Barr Plastics BD4848-16	48 x 48 x 16 in	1,220 lb
Barr Plastics BD4896-16	48 x 96 x 16 in	2,475 lb
Barr Plastics BD4896-32	48 x 96 x 32 in	4,804 lb

Notice how two makers’ 24 x 48 x 16 in floats land within a couple of pounds of each other. That is physics, not marketing: the same volume displaces the same water. A float’s own weight matters too; Barr lists 37 lb for its 24 x 48 x 16 in float, and that weight is part of your dead load.

How many dock floats do you need?

The basic sum is the same everywhere: dead load + live load = buoyancy you need, then divide by the rating of one float and round up.

• Dead load is the dock itself: frame, decking, hardware, ladders and the floats. Dock Builders Supply, a Florida dock supplier, says most residential lumber docks weigh typically 10 to 15 lb per square foot.
• Live load is what comes and goes: people, coolers, gear. It is never spread evenly; everyone ends up at the ladder end.
• Margin. Dock Builders Supply designs for about 40% submergence under the dead load and says floats should never be more than 50% submerged in normal use, leaving the rest for people.

Worked example (published by Dock Builders Supply, shown here as an illustration only). For a typical uncovered wooden residential dock, Dock Builders Supply multiplies the deck area by a factor of 28, 31 or 35 lb per square foot, depending on framing and decking. For an 8 x 16 ft dock with 2 x 6 pressure-treated decking it uses 31:

1. Deck area: 8 x 16 = 128 sq ft.
2. Buoyancy needed: 128 x 31 = 3,968 lb.
3. Floats: six 36 x 48 x 12 in floats rated 691 lb each = 4,146 lb, just over the target.

Barr Plastics publishes a similar rule of thumb: 3 to 6 floats per residential dock section, depending on size, weight and the freeboard you want. Both companies say these are guidelines; Dock Builders Supply takes no responsibility for the figures and recommends a structural engineer for specific designs. We don’t calculate safe loads for your dock. Use the method to understand the order of magnitude, then confirm the count with your float maker or a local dock builder, especially for a covered dock, a boat lift, a gangway resting on one side, or rough water.

Attaching floats to a dock frame

• Use the mounting slots or flange. Taylor Made’s minimum recommended hardware is a 3/8 x 3 in lag screw with a 3/8 in and a 5/8 in flat washer. Barr says its molded slots and holes suit wood, steel or aluminum frames.
• Bear on the frame, not the decking. Dock Builders Supply says each float must contact at least two cross-members.
• Spread them out. Put floats in every corner with no more than 8 ft between them (Dock Builders Supply). Barr suggests at least one float at each end of a walkway with more in the middle, and on a platform four corners plus two between them lengthwise.
• Don’t join floats to each other. Taylor Made says its floats are not designed to attach to each other; they attach to the dock.
• Secure them for the long haul. TVA requires every float to be firmly fixed to its structure with materials that can stand prolonged wave wash and weather. Use corrosion-resistant hardware.

Then anchor the finished dock properly: see how to anchor a floating dock and our step-by-step floating dock installation guide.

Dock floats you can buy online

These encapsulated floats were in stock on Amazon when checked in October 2026. Hardware is not included with any of them. Prices change often.

Bigger sizes, such as 48 x 96 in floats, are usually bought from marine distributors by the pallet. Barr Plastics, for example, lists its 48 x 96 x 16 in float at $703.36 CAD (Canadian dollars) when checked in October 2026, with shipping extra. We did not find a published US retail price for that size that we could confirm. For the total cost of a dock, see floating dock cost.

How long dock floats last, and when to replace them

No maker we checked publishes an expected service life in years, but warranties give a hint: Taylor Made offers an 8-year flotation warranty, Dock Edge+ 10 years on the float above, and Barr Plastics and Eagle Float 15 years. Vermont expects any foam covering to last at least 10 years. TVA’s rule puts the test simply: replace flotation when it no longer does its job, or when it cracks, fragments, sheds beads or becomes waterlogged. In practice, walk the dock each spring: a corner that sits lower than the rest, a cracked shell or foam showing through are your cues. Replace like with like so the dock floats level, and dispose of old foam properly; Vermont, for one, sends old unencapsulated floats to approved facilities such as transfer stations.

Where inflatable docks fit

An inflatable dock needs no separate floats at all: the air chamber is the float, and it packs away in a bag. It suits swimming, lounging and seasonal use rather than a permanent walkway to a boat. If you are weighing the two routes, read building a floating dock vs buying inflatable, floating dock kits vs inflatable docks and inflatable vs rigid floating docks.

Dock float questions

What are encapsulated dock floats?

Floats whose foam core is sealed inside a hard shell, usually rotomolded polyethylene over EPS foam. The shell keeps the foam from breaking apart in the water, and the foam keeps the float up if the shell is holed. Many lakes now require them.

How much weight does a dock float hold?

Whatever the maker states for that size, and that figure assumes the float is pushed fully under water. Published examples run from 260 lb (Dock Edge+ 24 x 48 x 8 in) to 600 lb (Taylor Made 24 x 48 x 16 in) and 2,475 lb (Barr Plastics 48 x 96 x 16 in). Part of it goes to holding up the dock itself.

How many floats does an 8 x 16 ft dock need?

In Dock Builders Supply’s published example, an 8 x 16 ft wooden dock needs about 3,968 lb of buoyancy, met by six 691 lb floats. Your number depends on your materials, your loads and the freeboard you want, so confirm with your float maker or dock builder.

Can I use plastic barrels as floating dock floats?

Check your rules first. TVA prohibits previously used drums or containers for flotation on its lakes, and Illinois allows metal drums only if foam-filled. Where drums are allowed, never use one that held chemicals or fuel.

Are foam dock floats bad for the lake?

Bare foam can break into beads and litter, which is why TVA, Vermont and Ameren at Lake of the Ozarks restrict it. Encapsulated foam floats and air-filled floats are the accepted alternatives.

Can I replace just one float?

Usually, yes: floats are bolted on individually. Match the size and rating of the others so the dock stays level, and if several are failing at once, plan to replace the set.