The scaffolding utilized is light-duty, rated at 25 pounds per square foot. If you multiply 35 square feet by 25 pounds per square foot, you may load the scaffolding with no more than 875 pounds. If it were me, I'd take it easy and load it only with enough material to cover my scaffold surface, which will be about 70 pounds. You should be able to lift that without any trouble. If you were to load it with more than 70 pounds, you might have a problem later when you try to dismount from your scaffold. Be careful not to overload it. As for the material itself, most commonly used scaffolding materials are wood or metal. Wood is usually preferred over metal because it's less likely to cause a serious injury if you fall from the scaffold. The average person can withstand falling from a height of 10 feet without serious injury about half the time if they land on their feet but never attempt to jump back up onto the scaffold. People working on high roofs often use scaffolds to get closer to the work. The roofing material itself can be very dangerous if not handled properly. It's best to avoid handling any roofing material unless you have adequate protection, such as protective gloves or gear. Some people also choose to climb up onto the roof using this method instead of taking an open elevator up there.