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What is Weathering (Cor-ten) Steel?2018-12-13T21:13:24+00:00

Weathering Steel is a high strength, low alloy steel, which means it has significantly enhanced resistance to plain cold rolled carbon steel. It is developed with corrosion-retarding 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 sculpture. 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?2019-01-07T00:03:05+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 from exposure to Weathering Steel during the patinazation process.

The best way to prevent staining is to incorporate permanent design details that divert 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?2019-01-06T23:59:02+00:00

Sierra Steeltiles are a non-combustible roof and will never contribute to flame-spread. A unique feature of the Steeltiles is the air space formed under them in manufacturing. This air space gives a buffer between the roof deck and hot coals that may land on the roof during a fire. Most metal roofing, like standing seam and ag panels, lay directly onto roof decks. This condition can promote direct heat transfer from burning coals that can ignite the wood roof surface below. Sierra Steeltiles are predominately raised off the roof to prevent a fire hazard through direct heat transfer.

There are special underlayments that further enhance fire resistance under a non-combustible metal roof. Ask your architect or installers for more information on these.

How long will Sierra Steeltiles last?2019-01-06T23:59:34+00:00

Installations with Steeltiles extend back to around 1972—more than 40 years—many of which are still in service today. Tests have shown how after 30 years of their exposure in Kirkwood, California, have retained more than 80% of the original base metal. We are in the process of having a certified testing laboratory evaluate the degradation of tiles with 20 and 40 years of exposure. Check this site often to learn developments in this testing.

Proper installation is very important with Sierra Steeltiles as it is with any roofing. Follow the instructions and recommendations for the best, longest lasting performance.

How does the oxidation of Weathering Steel work?2019-01-07T00:03:58+00:00

The oxidation on Weathering Steel is very desirable. It is often referred to as “useful corrosion,” as it adds greatly to the lifecycle of the metal. It also saves time and money associated with painting and maintenance.

The added copper, nickel, silicone, chromium, and manganese allow weathering steel to form a tight layer of rust when exposed to weather. It is self-sealing and self-healing. Scratches are quickly protected with a new oxide coating.

What about sustainability and recyclability?2019-01-07T00:00:12+00:00

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

How does the color change?2019-01-07T00:01:42+00:00

Sierra Steeltile Roofing is fabricated and shipped in its smooth, bare metal state.

The weathering process greatly depends on environmental conditions. When the metal is produced it is a typical bare metal. After exposure to moisture and the elements the protective oxide finish develops and achieves an orangish rust color. Over time, the oxide coating becomes a very attractive deep purple-brown patina. This finish has been known to last decades as it protects the base metal from continued rusting typical in plain, bare metal.

Contributing factors include:

    • The amount of exposure to rain, sun, and wind accelerates the process faster than a shady, protected area.
    • Atmospheric environments impact oxide development. Frequent wet-dry cycles like moisture from rainfall or dew then dried by the sun, are important for this process.
    • Atmospheric contamination has an effect. In moderate industrial environments, Weathering Steel 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?2019-01-07T00:02:34+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 more than 40 years. Kirkwood’s average snowfall is 500” per season, and skiers, homeowners, and contractors know it 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 prevent unsafe ice and snow conditions. More information on patented roof ice melt systems can be found at Summit Ice Melt Systems.
To further provide convenience and safety, one may consider adding gutters and downspouts, heated with heater cables extended from the roof ice melt system, to maintain the safe disposal of the meltwater. A snow retention system, combined with a roof ice melt system and heated gutter 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?2019-01-07T00:02:00+00:00

No. 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? There are many ways to improperly install the tiles, and correct installation is a key factor to longevity.

Normal good practices, such as proper flashing work, maintaining positive drainage at every point on the roof, 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?2018-11-30T04:06:04+00:00

Yes. Fortunately, the unique design of Sierra Steeltiles virtually eliminates this condition as they have only edges in contact that do net trap water. Overlapping surfaces, like side laps along a corrugated metal roofing panel, wick water up between the layers through capillary action. “Rust packs” can form from the breakdown of the normal oxide formation.

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

What is the proper handling and care of Sierra Steeltiles?2018-11-30T04:04:53+00:00

Sierra Steeltiles will arrive in heavy duty cardboard boxes on a pallet. They shall be kept safe and dry in wrapped  on the 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.
In general, the corrosion resistance and appearance of weathering steel is not affected by cleanliness. However, it is recommended areas of high visibility where a uniform appearance is desired, be handled with cleanliness in mind.

Can you get electrolysis from dissimilar metals installed with Weathering Steel?2018-11-30T03:48:47+00:00

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

It is advised that dissimilar metals, if necessary in a roofing application, be coated with a protective barrier or separated to isolate the metals. Runoff from dissimilar metals, for example 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?2018-11-30T04:23:42+00:00

Basic maintenance of keeping the roof free of debris, ensuring good drainage around chimneys, skylights, etc., is all that is needed. 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?2018-11-30T04:15:25+00:00

Bare cold rolled metal is much less expensive than 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 is not a characteristic of cold rolled steel. It also takes on a very orangey oxidation, and the unstable rust breaks off in scales until the corrosion wears through the metal.

Weathering Steel uses expensive rust inhibitors like copper, phosphorus, chromium, manganese, nickel and silicon. The elements clog the pores at the metal surface, and form a very tight, protective oxide finish that minimizes corrosion.

Can Weathering Steel be used by the ocean?2018-11-30T04:14:28+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?2019-01-07T00:03:31+00:00

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

Ice prevention systems, such as Summit Ice Melt Systems PRO Ice melt system (, prevent dangerous ice formations along eaves and valleys in snow climates. Snow retention devices should also be considered for snow climates.