EPS flotation structures exhibit excellent rebound characteristics with minimum rocking, provide less resistance to breaking waves and are quieter than those with other types of flotation such as drum floats.

Product Focus: Flotation

In summer months, it is not unusual to find the nearest watering hole filled with people escaping the heat and enjoying the water as well as sights and sounds. Many water-related activities are made safer with the use of expanded polystyrene (EPS) from floating docks to life-saving devices and buoys to surf and boogie boards. Whether you recognize it or not, EPS is everywhere on the waterfront.

Flotation devices have evolved over the years due to the introduction of new materials. Prior to the invention of foam plastics, in the early 1960’s, wood or empty drums were commonly used in flotation docks. Due to its lightweight and buoyant characteristics EPS has become the most popular flotation product on the market today.
 

Water absorption tests developed by the American Society for Testing Materials (ASTM) does not specifically apply to flotation devices. The Corp of Engineers implements a majority of the standards followed by manufacturers and distributors. Frederic Hunt, a marina consultant, developed a simple test to determine water absorption of foam flotation docks. The “Hunt Absorption Test” is administered to obtain a preliminary indication of the relative absorption of foams. No governing body including the Corps of Engineers references this test as a standardized and reliable test. It is most widely used as an advertising and marketing tool.

Advancements in processing helped polyethylene coated expanded polystyrene gain wide acceptance. It is now the dominant flotation device due to its long life and durability. EPS billets are able to support 55 lbs per cubic feet, as compared to wood, which is approximately 20 to 40 times heavier, but can only support about 18 to 28 lbs. The polyethylene should be a minimal thickness of 0.125. For areas affected by ice, thicknesses should increase to at least 0.187 inch. The tubs have an estimated life span of over 40 years and even if the coating cracks or are punctured, it will remain buoyant for approximately 15 to 20 years. Corps of Engineers concluded that encapsulated flotation devices would last three to four times longer than exposed EPS.

As the popularity of EPS floatation devices grew, new uses and designs emerged. Floating homes received national attention after being featured in the movie, “Sleepless in Seattle”. Entire “floating neighborhoods” dot the west coast of the US and Canada. The houses range in size from 450 sq.f. to over 3,000 sq.f. The Floating Homes Association defines the structure as “a legally-permitted structure, with no means of self-propulsion, which occupies a permanent berth and is subject to property taxes”. There are a lot of similarities to a land home although there is no lawn to mow and instead of pesky rabbits, there are loud Canadian geese to contend with.

The homes cannot float on the polyurethane coated EPS tubs as seen under docks. Due to the extreme weight of the structure, EPS is incorporated as the core of a reinforced concrete platform. International Marine Floatation Systems, Inc. (IMFS) is a major manufacturer of floating homes. Their design consists of blocks of EPS with steel reinforced concrete walls at 10 to 15 ft on centers and a top slab. Underslab items, like plumbing, are encapsulated by the EPS prior to casting the concrete. They prefer to use a non-structural coating to protect the EPS from various marine wildlife and abrasions. Some of the platforms are over six feet high. All underfloor voids are filled with EPS to insure an unsinkable home.

These unique homes are constructed to meet and often exceed local and regional building code standards. The floating foundation platforms are one-piece engineered structures to allow construction to meet local building codes. They are also fireproof. Just as a land home, the occupants are fully serviced with water, sewer, cable, and telephone. Unlike a conventional boat, the floating platforms never require expensive haul-out for painting or scraping below the water line. Since EPS is utilized in the foundation construction, it is completely insulated from the variations in water temperature, including ice conditions. Damage due to freeze/thaw cycles are minimalized.

This foundation design is also used for larger structures, including a floating restaurant, office building, and public washrooms in Lake Pleasant, Phoenix Arizona and a floating swimming pool in Mississippi River, Alton Illinois. By joining the platforms, floating walkways and roads can be assembled.

Flotation devices provide another example of how expanded polystyrene is utilized in a variety of unexpected applications. In this case, it also “expands” the opportunities to safely enjoy the waterfront and water activities.