If you have a metal roof, forget about any attic mounting: it just won't be reliable, whether you have windows in the attic or not. The Tampa-St pete area has a quirky situation becasue WTSP transmitter lies in a different location that the other major transmitters do, and really requires it's own antenna to insure reliable reception. I would us a small-two antenna system consisting of a Winegard HD-7694P VHF-high band plus UHF antenna aimed at 130 degrees as measured by your compass, and a VHF high-band yagi , like a
Winegard YA-6713 mounted the same mast 4' above the primary antenna aimed at 310 degrees by your compass. Combine the two antenna by using a Channel Master channel 10 JoinTenna , and run the cable to a proper grounding system and then to your TV set: if you have multiple TV sets that you want to run from the antenna, you can use a distribution amplifier like a Channel Master CM 341x where X=the even number of TV sets that you have in the house.
http://www.channelmaster.com/product.php?catID=40http:www.winegard.com/kbase/upload/HD7694P.pdf
http://www.winegard.com/kbase/upload/ya-6713.pdfhttp://www.warrenelectronics.com/Antenn ... tennas.htmhttp://manuals.solidsignal.com/AntInstallGuide.pdf