I mean mounted above the roof, ideally between 3 to 5 feet. Most masts are sold in 5 foot lengths. With an eave, chimney or tripod mount, that height is easily achieved.
If you are going to feed to 3 TVs. You will get into a distribution amp situation. The channel master 3414 is an effective way to split a over the air signal into different rooms. They are available 2, 4 or 8 way models and keep signal losses down.
http://www.amazon.com/Channel-Master.../dp/B001PI09SE On long runs and/or several splits, you lose quite a bit of signal. The distribution amp helps keep that from getting out of hand.
Cheers.