Ok , the top of a 3 story house will be more then good for Digital Tv Reception.
Due to the Well Known situation with KCWX VHF low band channel 05 , MyNetwork and This Tv.
http://en.wikipedia.org/wiki/KCWX.
And KCWX VHF high band channel 08 that will not be on the air until the middle of 2013 and will be a fill in transmitter.
KCWX channel 05 will remain the primary signal.
_______________________
A All channel antenna is required.
I recommend a All Channel antenna , all channels are ,
VHF low band channels 2 thru 6.
VHF high band channels 7 thru 13.
UHF band channels 14 thru 51.
______________________________
Above the roof install a Winegard HD7000R antenna aimed at about 210 degree magnetic compass direction.
Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.html.
No preamplifier is required.
For 1 Tv connection use No splitter.
For 2 Tv's connected use a common simple 2 way splitter.
For 3 tv's connected use a common simple 3 way splitter.
___________________________________________________
The HD7000R antenna is a little directional in the forward direction , and that's good for the reception of channel 05.
However the HD7000R is not all that directional.
And will receive the strong signal strength Digital Tv stations to the , North East , South East , South west , West.
And that is all the Digital Tv stations that are required to receive.
_________________________________________
Guy wires Are Not used for mounting the HD7000R above the roof.
A simple antenna mount such as ,
http://www.ronard.com/909911.html ,
http://www.ronard.com/34424560.html #4560 ,
http://www.ronard.com/ychim.html ,
http://www.ronard.com.
Buy the ronard antenna mounts at solidsignal by typing the word ronard in the solidsignal search box.
Here are some places to buy antennas and etc. ,
http://www.solidsignal.com ,
http://www.amazon.com ,
http://www.winegarddirect.com.
____________
As always trees and tree leaves do a real fine job of reducing or blocking Tv reception and so do buildings and other obstructions.
It is best to install antenna/s at a location that has the least amount to no amount of obstructions of any type or kind in the directions of reception.
The Tv/s Must Channel Scan for the Broadcast Tv Channels , some times named the 'Air Channels' or 'Antenna Channels' in the Tv setup menu because the Tv transmissions travel through the air from the transmitting antenna to the receiving antenna.
DO NOT channel scan for cable tv channels.