When it comes to metal roofing, the warranties that are available are in regards to the metal coating and substrates, not the actual metal itself.
Most warranties offer protection to the end user in three areas:
- Film Integrity – The paint will not crack, flake, chip or peel from the metal panel.
- Chalk – The paint system will not lose its original gloss beyond certain warranty limits. Chalking is caused by a natural breakdown due to ultraviolet rays from the sun. Most warranties cover a rating of 8 or higher over 20 years.
- Fade – The paint system will not lose its original color beyond certain warranty limits. Fading occurs naturally over time due to exposure to the elements. Fade is measured in Hunter Units, and most warranties cover up to a 5 Hunter Unit differential over a 20-year period.
Metal roofing coated in Ceram-a-Star 1050(R), a silicon-modified polyester, is covered by a 40-year warranty.
While Galvalume panels typically come with a 20-year warranty, galvanized panels do not have a warranty. A galvanized panel with a high rating, however, will still have a good resistance to corrosion, even without the warranty protection.
Keep in mind that temperature variations between the outside and interior air mass can cause condensation on inside panel surfaces. Proper venting, air flow, and the use of a proper vapor barrier can eliminate this problem. If left unattended, condensation can cause premature degradation of the metal and void any applicable warranty.