Whatever you do do not put holes in your roof to attach your antenna.
Installing antenna on metal roof.
The key is that the antenna feed point which is usually at the mounting bracket should be the same physical level as the metal roof to offer the best ground plane effect.
But what if you have a metal roof.
So you may want to put the mount on the ridge capping at the top of the roof.
Thankfully there are special indoor antennae which will circumvent this problem and help you watch tv despite having metal roofs.
I always recommend mounting tv antennas as high as possible.
Tin roof mount where to place the mount.
A metal roof discourages the transfer of signal by reflecting it away from you.
In order to take advantage of a metal roof as a ground plane you cannot elevate a quarter wave vertical high above a metal roof.
Be sure that the antenna can see over the roof.
You can also buy non penetrating mounts that use weights rather than screws to hold them in place.