Is it necessary to install the lightning rod for the 3 and half buildings? How much will it cost if it's packed?
If the surrounding floor is higher than it is, I don't recommend it. If it's safe, it's ok. In fact, you can also begin to install, easy to attract lightning is not as long as it is metal, to extend to the house that used a thick plastic tube wrapped until the ground position is good, so also save some money.
The building must install lightning arrester, otherwise the acceptance cannot pass, if you really want to install can, round 6-8 diameter on your roof from high to low around a week received the ground, with 40 angle into the ground 2 meters.
I don't think it's necessary to install it, because the center of the cover of the lightning rod is down to 45 degrees, so there are 6-7 stories 20-25 meters across from your house