Double-Wrapped Foam Cores
By double-wrapping your spa cover's foam cores, you are adding an extra layer of protection against water absorption.
Imagine going to your local home improvement store and purchasing a raw piece of EPS foam and putting it over your spa. The foam core will become waterlogged in about three to four months. Why?
To answer why, we need to look at the construction of EPS (Expanded PolyStrene) foam. Even though it is a closed-cell bead, there is air in between the beads that can be displaced with water. The difference in temperature between the water in your hot tub and the ambient temperature outside produces a pressure that forces the water vapor up into the foam core. Once there, the water condensates back into its liquid form and it trapped forever. In order to return that water to gaseous form to allow the smaller water molecules to escape from the foam, you would have to expose the foam to a heat source that would exceed the melting point of the foam.
An absorption volume of a particular EPS foam is dependent on it density or pounds of bead per cubic foot (pcf). The more bead you have per cubic foot, the less room in between the bead to get waterlogged. This is why we recommend 2 lb. density foam over 1.5 lb. density foam when water absorption is your primary replacement concern.
That said, let's get back to the double-wrapped foam option. As a manufacturer of spa covers since 1983, we haven't lasted this long by having our covers only last 4 months. To slow the absorption process, we seal the foam in a polyethylene vapor barrier. The outer vinyl covering as provides a barrier of protection. We refer to these features as part of the protective layering system.
Over time, as you use various chemicals in your spa to sanitize the water (including the use of an ozonator) the chemicals gas off and begin to break down the protective layering system. The strength of the protective layering system comes down to the number and quality of its components. This is where the double-wrapped foam core option comes in. By adding a second vapor barrier, you are adding to the strength of the protective layering system. On average, it will increase the overall effectiveness of the cover's water absorption resistance by approximately 25% or about 12-18 months.
If the average life of our standard cover is 5 years and given our average cover sale is $350, our customers typically pay about $70 per year to own a spa cover. If you can extend its life by a year for only a $30 option, wouldn't you do it?
If you have any additional questions regarding this option, feel free to contact us.