You boys are headed for trouble down the road. As much as everyone keeps pointing to the chimney to mount antennas on, it is a very bad idea. The longer the mast you mount and the larger the antenna you put up there, the faster your going to see your chimney need to be repaired.
The mast and antenna put a constant pressure on the chimney when the wind blows. Any vibration on that mast gets transferred right into the chimney. Over time, that constant vibration will crack the mortar holding the bricks together. Years ago, I thought the same as most of you that the chimney was a fine place to mount the TV antenna.
Ran into a brick layer and he filled me in on just what was going on. He made his living repairing all the cracked chimneys he ran across. He would drive around and look for any antenna that looked like it had been up on the chimney for a number of years. Once he found one, he would take out his high powered binoculars and take a gander at the chimney. Just about all the time he could find cracks. A knock on the owners door and he would introduce himself to the owner of the house. Explain why he stopped by. Those owners that thought he was yanking their chain were shortly corrected when he would hand them the binoculars. Told them where to look on the chimney.
Reason the bricklayer was so good at what he was doing, is that he knew once the home owner was informed of the problem, their home owner's insurance would not pay for any damage the chimney might cause if it lost any bricks onto the roof. He most of the time could talk the home owner into the job of repairing the chimney. He would also tell them that the antenna mounted on the chimney caused the damage.
So now that you have heard a true story about chimney damage caused by antennas, you can go do what you want.
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