Totung Roof

Mar 12

To-tung is that local term you’ll hear from the old-timers and seasoned contractors in the islands. While the rest of the world calls it corrugated metal, here, it's To-tung. Originally brought in during the sugar era because it was easy to ship and simple to install.

If you’ve spent any time looking at the rooflines in Kaimuki, Waialua, or the hills of Kalihi, you’ve seen it.

What Exactly is "To-tung"?

The name refers to the overlapping tongues or ribs of the corrugated metal panels. When two panels meet, they overlap by at least two waves (the tongues) to create a mechanical, watertight seal.

Why it’s a Hawaii favorite:

Heat Reflection: Unlike asphalt shingles that soak up the sun and turn your attic into an oven, To-tung reflects a huge percentage of radiant heat. This is why older homes without AC stay surprisingly comfortable.
Heavy Rain Shed: During a downpour, water needs to move—fast. The deep grooves of a To-tung roof act like mini-gutters, channeling massive amounts of water off the roof before it can seep under the laps.
Lightweight Strength: It’s incredibly light, which is crucial for older single-wall homes or post-and-pier structures that can't support the heavy load of clay or concrete tiles.

The Challenge

On older galvanized steel roofs, you’ll notice rust starting at the very edges or around the screw heads. Once the protective zinc coating is eaten away by the elements, the iron in the steel begins to oxidize. If left alone, those tiny orange spots turn into pinhole leaks that can turn into bigger holes.

The Modern FIXIT Upgrade: Galvalume & Aluminum

If your old roof is reaching the end of the line, we don't just replace it with the same old stuff.

Galvalume: This is the modern standard for Hawaii. It’s steel coated with a mix of aluminum and zinc. It lasts up to twice as long as traditional galvanized steel, especially in coastal environments.
Factory-Painted Aluminum: For homes literally across the street from the ocean, aluminum is the gold standard. It doesn't rust, period.
Cool Roof Coatings: If your To-tung is still structurally sound but looking bad, we can apply high-reflectivity white coatings. This seals small leaks and can drop your indoor temperature by another 5–10 degrees.
Fasteners: Each screw has a small neoprene (rubber) washer. That rubber eventually dries out, cracks, and shrinks. This creates a tiny gap that allows water to get through. If your roof is more than 10 years old, it might just need a Fastener Refresh. Swapping out old, brittle screws for new ones with fresh seals can add years of life to your roof for a fraction of the cost of a full replacement.