Industry Thickest 6 mil Vapor Barrier

BOTTOM LINE: Thermal Guardian premium spa covers last longer in large part due to their industry-leading 6mil vapor barrier film and superior sealing technology.

Unfortunately, spa covers do eventually get waterlogged and become too heavy to use. We may not be able to control whether it happens at all, but we can definitely increase the cover's defense and push that water saturation date back!

Here's the what, why and how of spa cover waterlogging and how our Thermal Guardian outperform the competition. It all starts with the vapor barrier film and how it is sealed.

FACT: Expanded PolyStyrene (EPS) foam cores will become totally saturated with water when used in a spa cover application.

Why? Even though the beads are closed-cell, the structure of EPS is not. Depending upon the density of the board (pounds of bead per cubic foot), a foam core has honeycomb channels in between the molded beads. As the water vapor penetrates the foam core and then cools and condensates in its liquid form, the water becomes trapped. Spas form a natural pressure situation that pushes hot water vapor upward. The spa cover is holding that water vapor back.

Imagine a raw piece of foam suspended above a spa. Without any protection, this foam core would be fully saturated in a matter of months. Spa cover manufacturers would obviously go out of business if the cores waterlogged in a couple of months so they need to protect the core. That's where the vapor barrier film comes in. It stops the water vapor from penetrating the foam core.

If this is the case, why does the core eventually still waterlog? The answer to this question can be a couple of things. Some are out of the control of the manufacturer, but some are if the maker is willing invest in technology to produce a high-quality product.

First off, the vapor barrier film is only as good as its sealing technology. We have a hard time believing that some cover manufacturers still tape their film shut, but they do. Here is a breakdown of the technologies employed.

1) Taping: In our opinion, this is a step above nothing.  When compared to what other companies do, this might as well be considered useless.
2) Heat Shrinking: Once thought to be the premium way of sealing spa cover foam cores, this expensive process has proved to do more harm to the film than good.  Many companies that adopted this technique have scrapped their equipment because it has been found, most notably by Hot Spring Spas who was an early adopter of the technology, that during the shrink process the film becomes very porous. Heat-shrunk foam cores have been reported to absorb water to their maximum level in as little as 12-18 months.  The only companies that continue this process are those that cannot bring themselves to turn their back on a very expensive capital investment.
3) NiChrome Wire Heat Seal: Typically done with a hand-held, nichrome-wire heat sealing wand, this process provides an adequate seal as long as the operator pieces the seals together correctly.  Hand-sealers are never over 40" long causing the seals of most spa covers to be pieced together. Also, the wand features a sealing wire which makes a razor-thin seal.
4) Impulse Band Heat Seal: The preferred seal technology of our spa cover partner, this sealer produces a seal that is 1/8" thick. With this we are able to not only make a complete seal, but also produce a 1/8" weld that outperforms the inconsistent results of nichrome wire hand-sealers. Combined with our 6 mil vapor barrier, our Thermal Guardian spa covers can outperform the competition in fighting water absorption in the foam core.

Next, the chemicals you put into your spa to sanitize the water gas off and deteriorate the vapor barrier film. Over time, the film itself is broken down leaving the foam defenseless. Though you cannot stop the chemicals from doing their dirty work, you can toughen up the film. We use a 6 mil linear low-density polyethylene film as our vapor barrier. Compared to the films of covers, our film is up to 3X stronger. Also, by using low-density PE film instead of the more popular high-density film, our vapor barrier degrades more gracefully over time. Did the film on your last cover start coming apart and get stuck in your filter? That's because high-density film shatters as it weakens. Low-density has more elasticity and will not shatter. This keeps the vapor barrier intact longer offer its protection longer leading to longer cover life.