Is there an underside and top to a corrugated plate?
Yes. It’s very important that you lay the corrugated sheets with the correct side up to ensure a waterproof seal. The side with the Aquaplan logo on it is the top. The Aquaplan logo is covered at the overlap with the ridge cap or another corrugated sheet. When installed correctly, no logos are visible on your roof. For the black corrugated sheet, the top is the shiniest side.