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What is Weathering (Cor-ten) Steel?2020-09-27T23:33:22+00:00

Weathering Steel is a high-strength, low-alloy steel, with excellent atmospheric corrosion resistance due to the addition of expensive elements such as copper, nickel, chromium, silicone, manganese, and phosphorus.

The rich patina of Weathering Steel is being seen more often in bridge building, metal beam guard rails, power poles, structures, and sculptures. When you look around you will see it everywhere. The aesthetic value of this weathered and textured material, combined with the ease of handling, forming, and low maintenance, makes it a practical material with many uses.
It develops a unique, natural oxide coating that, when fully mature, is dense, tightly adherent, and impervious to further atmospheric corrosion.

Can Weathering Steel cause rust stains on surrounding features?2020-09-27T23:36:49+00:00

Yes. Weathering Steel releases dissolved iron when water washes over the surface, particularly when the surface is subject to frequent rain during the early months of exposure. Porous materials such as stucco, wood, and concrete sidewalks will experience rust staining if exposed to runoff during the patinazation process.

Therefore, to prevent staining, incorporate permanent design details that divert roof runoff water away from porous surfaces. The use of gutters, extended overhangs, natural landscaping, and some strategic architectural planning can minimize the staining effect.

Are Sierra Steeltiles fire-rated?2020-09-27T23:42:31+00:00

Sierra Steeltiles are a non-combustible roof material that will never contribute to flame spread. A unique design feature of the Steeltiles is the air space formed within the tile walls. This air space creates a thermal buffer between the roof deck and hot embers that may land on the roof during a fire. Most metal roofing, like standing seam and agricultural panels, lay directly on roof decks. This condition allows direct heat transfer from burning embers that can ignite the wood roof surface below. The top surfaces of Sierra Steeltiles are raised off the roof to prevent a fire hazard through direct heat transfer.

There are special underlayments that further enhance fire resistance with a non-combustible Sierra Steeltile roof. Ask your architect or installer for more information on these.

How long will Sierra Steeltiles last?2020-09-27T23:46:51+00:00

Installations of Steeltiles extend back to 1972—almost 50 years. Tests have shown that after 30 years of continuous exposure in Kirkwood, California, Sierra Steeltiles retained more than 80% of the original base metal. We are in the process of having a certified testing laboratory evaluate the wear of the tiles after 20 and 40 years of exposure. Check this site often to keep up with the latest developments in this testing process.

As with any roofing material, proper installation is very important with Sierra Steeltiles. Follow the instructions and recommendations for the best, longest lasting performance.

How does the oxidation of Weathering Steel work?2020-09-27T23:52:34+00:00

The protective oxidation layer that forms on Weathering Steel is the attractive feature that makes it so desirable as a roofing material. Once the layer is formed, special alloy elements in the material greatly slow down further oxidation, adding to the long life of the metal.

Unlike painted roofing material which will fade over time or become scratched or require re-painting, Sierra Steeltiles’ oxide layer is self-sealing and self-healing. Any scratches are quickly protected with a new oxide coating.

What about sustainability and recyclability?2020-09-28T00:46:28+00:00

Sierra Steeltiles are made from 88% recycled steel, and are 100% recyclable.

How does the color change?2020-09-28T00:01:52+00:00

Sierra Steeltiles are formed and shipped in their smooth, non-oxidized, bare metal state.

The weathering process greatly depends on environmental conditions. As the protective oxide finish develops it achieves an orange/rust color. Over time, the oxide coating develops a very attractive deep purple-brown toned patina. This finish has been known to last decades as it protects the base metal from continued rusting, as is typical with plain steel.

Contributing factors include:

    • Frequent we/dry cycles (rain or dew, then sun) accelerate the oxidation process.
    • Atmospheric contamination has an effect. In moderate industrial environments, the oxide coating usually matures rapidly and achieves the darkest possible tone.
    • In rural locations, the oxide coating develops more slowly and generally in a lighter tone.
    • In arid climates the weathering process occurs much more slowly.
What about ice prevention and snow retention with Sierra Steeltiles?2020-09-28T00:07:10+00:00

Weathering steel roofing is often used in snow country, and Sierra Steeltiles are renowned for braving the heaviest winters in Kirkwood, California for almost 50 years. Kirkwood’s average snowfall is 500” per season and skiers, homeowners, and contractors know it’s notorious as one of the heaviest ice and snowfall areas in America.
While Weathering Steel demonstrates greater friction against snow sliding compared to painted and other bare metal roofing, it can still experience ice and snow shedding. Where falling ice and snow present a safety hazard property owners should consider integrating an engineered snow retention device, along with an ice melt system, to minimize unsafe ice and snow conditions. More information on patented roof ice melt systems can be found at Summit Ice Melt Systems.
To provide even greater convenience and safety one may consider adding heated gutters and downspouts. Using heater cables extended from the roof ice melt system, they promote the safe disposal of the meltwater. A snow retention system, combined with a roof ice melt system and heated gutters and downspouts will provide the maximum safety and comfort in winter conditions, and also minimize the potential staining of runoff from the Weathering Steel.

Is there a warranty with Sierra Steeltiles?2020-09-28T00:40:29+00:00

While we expect a properly installed Sierra Steeltile roof to perform 75-80 years, or longer, there is no warranty given to this product. Why? Improperly installed tiles can result in a shorter-than-expected product lifespan. The countless Sierra Steeltile installations dating back almost 50 years are the best gauge of the product’s superior performance, value, and long life.

Normal good roofing practices, such as proper flashing work, maintaining positive drainage at every point on the roof, and maintenance which includes keeping leaves and dirt from accumulating (especially in valleys and behind skylights and chimneys), will ensure the longest life expectancy possible.

Are overlapping surfaces of Weathering Steel a concern?2020-09-28T00:45:45+00:00

Yes, however, the unique design of Sierra Steeltiles virtually eliminates this condition as there is only a limited amount of edge contact that does not trap nor wick water. Normally overlapping surfaces, like side laps along a corrugated metal roofing panel, naturally siphons water up between the layers through capillary action, resulting in  “rust packs.”

It is advised that at flashing overlaps at valleys and wall flashings, etc., a sealant be applied along the joint to stop water intrusion by capillary action.

What is the proper handling and care of Sierra Steeltiles?2020-09-28T00:55:23+00:00

Sierra Steeltiles will arrive in heavy duty cardboard boxes on a pallet. They shall be kept safely wrapped on pallets prior to installation.
Care should be taken while handling Weathering Steel in the field to avoid unsightly gouges, scraps, and denting. Handle with gloves to keep as clean as possible, and keep away from mud, grease, oil, paint, concrete, mortar splatter, and other foreign substances. Paint, chalk, or crayon marks should be made in areas not visible in the final installation.
While minor soiling should weather off naturally on exposed surfaces, it might be beneficial to hose down the entire roof area at the completion of the installation.
It is recommended areas of high visibility where a uniform appearance is desired be handled with cleanliness in mind.

Can you get electrolysis or galvanic corrosion if dissimilar metals come in contact with Weathering Steel?2020-09-28T00:58:49+00:00

Yes. Electrolysis is the decomposition of dissimilar metals in contact with each other, in the presence of an electrolyte, such as water.

It is advised that dissimilar metals, if necessary in the roofing application, be coated with a protective barrier or separated from the Weathering Steel. Runoff from dissimilar metals, such as from an aluminum chimney flashing, can contribute to corrosion and affect the patina of Weathering Steel.

It is recommended that stainless steel fasteners be used to attach Sierra Steeltiles for best performance and greatest longevity.

What maintenance is required for Weathering Steel roofing?2020-09-28T00:59:57+00:00

Basic, normal maintenance of keeping the roof free of debris and ensuring good drainage around chimneys, skylights, etc., is all that is needed to maintain your Sierra Steeltiles roof. Good home maintenance dictates tree branches should be kept clear of the roof and siding, as well.

How does Weathering Steel compare to bare cold rolled metal?2020-09-28T01:04:30+00:00

Bare cold rolled metal is much less expensive than Weathering Steel and does not have the added alloy elements of Weathering Steel. Common sense dictates cold rolled steel should not be used as a roofing or siding because it is not corrosion resistant. Further, the International Building Code requires corrosion resistance in roofing materials which cold rolled steel cannot provide. It also takes on and maintains a very orange-toned oxidation, and the unstable rust formations continually break off in scales until the corrosion wears through the metal.

Weathering Steel uses expensive rust inhibiting alloy elements like copper, phosphorus, chromium, manganese, nickel and silicon. These elements clog the pores at the metal surface, forming a very tight, protective oxide finish that greatly slows corrosion.

Can Weathering Steel be used by the ocean?2020-09-28T01:06:18+00:00

Salt environments will accelerate the corrosion of most metals. It is recommended that installations be at least one to two miles from salt water environments.

What ice dam underlayments are compatible with Weathering Steel?2020-09-28T01:05:59+00:00

Ice dam underlayments, or membranes, help seal around fasteners to prevent water seepage in an ice dam condition. There are several manufacturers of membranes that have been designed for use with Weathering Steel. Most manufacturers recommend using a “High-temperature” type of underlayment, as there can be some heat accumulation under metal roofs.