What is Expandothane?

Expandothane is a premium, high-pressure spray-applied polyurea membrane. Upon application, it expands up to 7 times its original volume to fill every crack, void, and low spot on the roof deck. It cures in seconds to form a completely seamless, self-flashing, and monolithic waterproof barrier that conforms perfectly to your roof’s unique layout.

The Ultimate Shield: Henry’s Tropi-Cool® 100% Silicone Top Coat

To maximize the lifespan of the Expandothane membrane, we apply a high-solids layer of Henry’s Tropi-Cool® 100% Silicone over the top. This heavy-duty top coat creates a dual-layer defense system that provides distinct advantages:

Superior UV Defense & Energy Savings: Henry’s Tropi-Cool reflects the sun's harsh rays, significantly lowering roof surface temperatures and reducing cooling costs.

Ponding Water Resistance: Unlike acrylic or other traditional elastomeric coatings that break down under standing water, 100% silicone is completely moisture-cure. It will not degrade, crack, or delaminate even under prolonged ponding water.

Key Benefits of the System

Unbeatable Hail Resistance: Expandothane’s dense, rubberized core provides exceptional tensile strength and elongation. It acts as a shock absorber against severe weather, resisting heavy impact and preventing cracks, punctures, and leaks from heavy hail.

Completely Seamless Waterproofing: Because it is sprayed on and expands, there are zero seams, screws, or joints—eliminating the #1 places where traditional roofs fail and leak.

Long-Term Lifespan: This dual-layer system is engineered to last for decades. With a failure-free track record, it provides a permanent, restorable solution that can easily be recoated down the road to extend its life indefinitely—saving you the massive expense of a future tear-off.

Eco-Friendly Restoration: Applying this system over a structurally sound deck completely eliminates the need for a total roof tear-off, keeping tons of construction waste out of landfills.

Click on any of our Expandothane project photos below to see how this incredibly durable, high-tech system looks on a completed job site.