If you have used an inflatable paddleboard you at least have a basic understanding of the durability, rigidity and strength of our spa covers. Then imagine us using the best materials, manufacturing techniques and QC that the best inflatable paddle board brands are known for. That is The AIRCAP 1™ premium hot tub cover.

At thrml.™ we have no desire to offer products that are short of the best. We will never be inexpensive, our products are for those that want quality. Those that understand that if they buy our AIRCAP 1™ hot tub cover that not only will they have an amazing user experience with our products but they won't have to buy another cover again.

When our founder, a lifelong successful pool and spa industry entrepreneur set out to solve the problem of foam hot tub covers, he had specific demands directed at our team. One of them was that we will build nothing but the best. He was very specific on who we will model our highest expected QC standards after. There is cooler company that most people in the world are aware of, that builds the most most burly, bombproof, high quality products, they are not for everyone but if you purchase one, you understand it is a one time expense. That's what we strive for and we expect nothing less.

We hit golf balls at 160 mph at our covers to test for hail. He beat them with hammers. We tested them in scorching heat and below zero temps. We drove our 4000 lb trucks over them. We tested heavy snow loads. We sent them to Seattle in the heaviest atmospheric river the region has ever seen. Our head of product development, a former D1 offensive lineman stands and jumps on his everyday. We have thrown everything we can at The AIRCAP 1™ and it is yet to fail us.

The AIRCAP 1™ hot tub cover is constructed using drop stitch technology, the same high-performance method that makes modern inflatable paddleboards (SUPs) exceptionally tough and rigid. Drop stitch consists of two layers of durable, reinforced fabric connected by thousands of tightly woven polyester threads running perpendicularly between them. When inflated to the recommended pressure these threads pull taut and hold the layers rigidly apart, creating a flat, solid-feeling panel that distributes weight evenly and resists deformation. This results in a structure with high tear strength, excellent puncture resistance, superior UV and chemical resistance from the outer coatings, and the ability to withstand heavy loads, impacts, and repeated inflation/deflation cycles without losing integrity.

Traditional foam hot tub covers (vinyl-wrapped polystyrene or EPS foam panels) rely on a porous foam core for insulation and rigidity, but this core is inherently vulnerable. Over time, exposure to hot tub steam, chemicals, UV rays, rain, snow, and physical wear causes cracks, seam failures, or vapor penetration, allowing moisture to seep in and be absorbed by the foam's open cells. This leads to waterlogging (adding 20-50+ pounds), sagging, mold/mildew growth, cracking vinyl, and accelerated breakdown—typically requiring replacement every 3-5 years.

The foam lacks the tensile strength of drop stitch threads, so it crushes, compresses, or degrades under load, weather extremes, and it's fragile shortening its lifespan and reducing insulation efficiency as the saturated material conducts heat far more readily.

From a durability standpoint, the AIRCAP 1's drop stitch design is far superior because it eliminates the absorbent foam core entirely—the interior is simply pressurized air held by impermeable, high-tensile fabric layers. This prevents water absorption, mold, rot, or weight gain, while the thread network provides rock-hard rigidity comparable to hard-shell materials yet with flexibility to handle temperature fluctuations aided by our Patent Pending PRV's (pressure release valves). The result is a cover that lasts significantly longer (often 10-15+ years with proper care), resists punctures/tears better than degrading foam/vinyl, maintains consistent performance in harsh outdoor conditions, and avoids the common failure modes that plague traditional covers, making it a more reliable, low-maintenance upgrade for long-term hot tub protection.