1. Knowledge Base
  2. Technical Bulletins

Dissimilar Metals, Treated Lumber, Agriculture, and Other Corrosive Environments

Dissimilar Metals (Copper & Lead)
Please note that our published literature clearly states that copper should not be used with our roof system or near our roof system if any runoff from the copper will come in contact with our roof system. The Learning CD also contains a section on dissimilar metals:

1. In the DECRA Tile, Shake & Shingle Installation Guide on Page 10 we highlight “DO NOT USE COPPER OR LEAD WITH THIS ROOFING SYSTEM”
2. In the DECRA Shingle, DECRA Villa Tile and DECRA Shake XD Installation Guides in the panel labeled Roof Penetrations we have a note that reads: “Do not use lead or copper with this Steel Roofing System”

3. In the Specification Guides for Tile, Shake and Shingle Plus under Section 2.3 Accessories we list A. Timber Battens, and immediately underneath we highlight “Do NOT use LEAD or COPPER with this aluminum-zinc alloy coated steel roofing system.”

Treated Lumber
These warnings also apply to copper treated lumber. “CCA” (chromium copper arsenate) treated lumber is corrosive to steel. The new replacements recommended by the EPA to eliminate the chromium, like ACQ (alkaline copper quat) and copper azole sold under the trade names Preserve, NatureWood and Natural Select are known to be even more corrosive than CCA because of the higher copper content needed for them to be effective without the poisonous chromium.

Borate or Borax pressure-treated lumber does not corrode DECRA panels and is easy to distinguish from wood treated with copper because the copper treatments all give the
wood a green or greenish appearance while the borate keeps the wood’s natural yellow-brown color.

Since the battens used with a DECRA roof system are up in the roof system, and not in the soil, the most common lumber used for battens is untreated Douglas fir, spruce or
southern yellow pine.

Agricultural Installations and Other Corrosive Environments
Both physical and airborne contact between DECRA panels and any potentially corrosive materials or environments should be prevented. Examples of corrosive materials or environments may include contact with soil, fertilizer, lime, acids, feeds,
animal waste, manure, urine, decaying materials, absorptive materials, manufactured chemicals, excessive salt spray, etc;

Download the bulletin here