Windows should always have full glasses or be fitted with galvanized mesh with openings no greater than 20 mm and a wire thickness of at least 0.7 mm. Also vents should be secured with wire mesh. If there is room for a rat to pass, holes for pipes and wires should be covered with a tight-fitting galvanized sheet or sealed with wire mesh or concrete. Drain shafts must be secured with rat proof grits or covers. Downpipes and drains from sinks must open onto a sewer grit or cover.
Always use pipes that both in terms of material and design are rat safe. Plastic pipes for drainage must be completely smooth on the inside and without sharp bends. Rats often enter buildings through the sewer system, either because the pipes are old and brittle, or because new installations are made sloppily. Rats can, like mice, climb up to the roof. It can be prevented by placing metal collars on downpipes and by avoiding trellises and climbing plants against walls. A rough wall can be ensured by a 30 cm wide strip of smooth paint or varnish in the height of one meter. Ultrasound equipment is not effective against rats and does not keep them away.