To prevent a roof rat colony from nesting in your home, make sure that all the windows and vents are screened. Roof rats can also enter openings in walls, eaves and roof from the branches of trees. Trim all tree branches to further prevent entry.
As its name indicates, these species of rats are most likely to be found in higher places and upper levels of the home. Thus traps should be placed off the ground in the attic, rafters of the garage, on shelves and ledges. Rats are typically suspicious of new things in their environment and will avoid traps unless there is something very attractive on the trap. Roof rats may be attracted to simple food scraps including pieces of fruit and bacon. In addition, try putting the attractant out for a few days before setting the trap. This will get the rat used to eating at that location.
Toxic baits or rodenticides are intended to kill the rats when they eat the bait. Rodenticides are potentially harmful to non-targets such as people or pets if not applied correctly. It is advisable to first consult a pest control professional.