haddon,they should be in the floor joist.if you have a infrared temperature gun you can use it to locate where they are and the bore scope to determine how deep they are in.i did one last week and they were in about 3 1/2 feet. .i did it from the outside but 4 feet would be max for going from the outside..second option would be going through the floor above them if possible.third option would be going through the ceiling which is my last choice.as for the bore scope ,the pro vision works good.1/4 inch hole and your in.if you need to look up just dril the hole on a 45degree . ......schawee