Roofing in Nevada is ultraviolet light in the south and snow and ice in the north, with wind invited to both. Southern shingles lose granules and dry out in the felt long before a storm deserves credit, because the storm may not come for months. Tile and foam cover a lot of southern houses and crack, blister, or pond under sun that does not quit. Northern roofs carry weight, ice dams, and freeze-thaw at the eaves, closer to a Sierra problem than a Mojave one. Name the latitude before you name the stain.
From the ground, southern roofs show bald shingles, cracked tiles in the gravel, and foam that has chalked and split at a penetration. Leaks hide until a rare rain or a plumbing vent failure. Northern roofs show ice at the eaves, stained soffits after a thaw, and shingles lifted by wind coming off the Sierra. Do not climb to settle the argument. Say whether water appears only after rain, only during a thaw, or while a cooler or a bath fan runs. Those are different roofs in practice.
Ask what a repair includes at the boots, the walls, and the valleys. A single lifted shingle is not a tear-off. A tear-off needs underlayment, flashing, and a decision about the deck if it is soft. In the north, ask about ice and water protection along the eaves and about ventilation so the next winter does not repeat the dam. In the south, ask how the crew will keep from cracking tile, and whether foam is being recoated or replaced. Ask who pulls the permit and who hauls the debris.
Write the scope down, including what happens if the deck is rotten. A southern sun-baked field and a northern snow roof should never share a casual description. Say which one is over your head. Call the number on this page.