There are different types of sheet metal materials that can be utilized for roof-related flashings: aluminum, stainless steel, paint grip, galvanized steel, pre-finished steel and copper. The two that are most commonly utilized are aluminum and stainless steel. These metals are very durable to the outside elements and are easily fabricated when making roof-related flashings. Before choosing a metal product for your building’s roof related flashings, understanding the different types of metals and their optimal use for the proposed condition is the best way to assure the longevity and water tightness of your roofing system. 

Aluminum and stainless steel are commonly used for roof-related flashing such as copings, gravel guards, through-wall flashings, counter flashings, penetration pockets and roofing. The information provided below regarding these two metals is compiled from the Sheet Metal and Air-Conditioning Contractors’ National Association’s (SMACNA) Architectural Sheet Metal Manual.

Aluminum is very easy to fabricate to the desired conditions needed for sheet metal flashings. It can be left in a natural condition (mill finish) where it will weather into a uniform gray color. Special alloys can be anodized to achieve an array of colors and can be pre-painted with acrylic coatings to achieve specific colors. In addition, embossing or rolling can obtain textured surfaces.

Natural aluminum develops an oxide film on the surface of the metal when exposed to the elements. Acrylic coating provides the aluminum with a surface that helps to repel water and is highly resistant to corroding atmospheres. However, it does not withstand caustics or strong alkalines such as lime.

Aluminum is a lightweight, very corrosion resistant material when coated. It will not stain adjacent surfaces and is very workable and easily fabricated to meet the required configurations.

Avoid large, flat surfaces, which will cause oil-canning and waviness. Aluminum or stainless steel fasteners should be used when attachment is necessary. Aluminum cannot be soldered. Welding is an alternative but needs a skilled welder to assure a watertight joint. The use of rivets and sealants is the most commonly used application for sealing the joints. Avoid direct contact with dissimilar metals and with concrete or mortar. It is not recommended for through-wall flashing.

Stainless Steel:
Stainless steel is a durable, maintenance free, corrosion resistant material. There are different types of stainless steel materials. The most commonly used is the 300-series, which is typically used for roofing and roof-related flashing applications. Stainless steel can be used in conjunction with most other metals without concern of electrolysis.


Stainless steel has an excellent corrosion resistance when introduced to the outside elements and requires no artificial surface coatings applied for protection. It requires little maintenance after installation and is a self-cleaning product once any contaminants are removed from the surface. In addition, decay of the material is not a concern if exposed to mortar or concrete. With some metals, staining of adjacent surfaces is possible, but it is not a concern when using stainless steel.

Cleaning surfaces after fabrication and installation is necessary to remove contaminants that can lead to corrosion. As with any metal, avoid long and large flat surfaces to reduce waviness. Soldering techniques require a cooler soldering iron that needs to be heated longer to melt the solder. Special stainless steel flux should be utilized for appropriate soldering techniques.

Remember that metal flashings such as copings, gravel guards, pitch pans, counter flashings, and through-wall flashings are installed to complete the watertight integrity of the roofing system. Specifying the correct metals and having a properly installed flashing condition is the best way to assure a complete, watertight roofing system.

Look for more information on other types of steel in upcoming Chamberlin newsletter issues. For assistance in choosing the roof-related sheet metal that is right for your building, contact Chamberlin at 1-800-749-1432, or call your local Chamberlin office directly.