Siding is surprisingly durable in the harsh Utah sun and extreme mountain weather. While all substances will fade, siding fade is minimal, happens very slowly and any abnormal fading is covered by the lifetime transferable warranty. The Hunter’s Scale is the measure of fade used for siding. The Hunter E unit specifically measures color difference. As a reference, a Delta E of 1 Hunter unit is a barely noticeable color difference. A good warranty will guarantee products will not fade in excess of a Delta E of 4 Hunter units. Which in layman terms, means you are guaranteed color stability in the long term, even if living in an environment like Utah and Idaho.