Yes, they will work very well. As Butch said, however, the manufacturer's tuning chart is pretty worthless for such an installation. That's because the chart is usually for a ground mounted installation, or a roof top with only 4 or 8 radials. Two experiences with metal roof top verticals come to mind. Shortly after my brother and I got into CB radio, I went to spend the week with my grandmother in Alabama. Her house had a tin roof, so my dad rigged a clamp to fasten the mobile antenna near the edge. We were all blown away by how well that temporary setup worked. I could hear as well as the guys around me who were running ground plane type antennas, and managed a respectable transmit signal too. When the higher hf bands were beginning to wake up in 1977, a friend who ran a furniture and appliance store decided to put a 15 meter vertical on the roof of his 4,000 sqft steel building. His vertical was made from 2 pieces of tubing which his store was selling as "closeline poles." He fastened them together, and installed it on a television antenna tripod, using a glass catchup bottle as the base insulator between the bottom of the antenna and the roof. At the time, I was running a Swan 500CX with a 2 element Hi-gain quad at 60 feet. My friend was a mile away, running that vertical with a Viking Ranger that belonged to his uncle. He could work anything he could hear with that rig on AM, and he would beat me in the pileups 99% of the time with his 75 watts on cw vs my 300. Mike Duke, K5XU American Council of Blind Radio Amateurs