Rats can get inside the house just about anywhere. But typically, rats would go into the crawl space as there are plenty of places they could wander around. Sometimes, the rats are too big to climb into the insulation. So compared to mice, they are easier to contain. Mice are more dangerous as they are small in size and could chew through walls, vinyl and wood. Anyhow, both rats and mice could cause electrical fires by chewing through wires.
It is easy to identify rats/mice in the crawl space as you could see traces of droppings they leave behind. So, what to do when you identify for sure some rats are inside the crawl space then? You could buy some traps and set them up along the trails rats would follow, or, it is better to just find a professional pest control company to come in and handle it for you.
Here are some good rat control companies I've heard in Seattle.
Clean Crawls, 425-462-6748
The original crawlspace clean-out and insulation upgrade company in The Pacific Northwest. They are recommended by at least two of my friends.
Athena Pest Control, Inc 206-905-1065
A local women owned, licensed and insured Pest Control Company in Bellevue King County. Expertise in the Identification, Elimination and Control of the following Pests: Ants, Bees, Yellow Jackets and Wasps Birds Mice and Rats Moles Spiders.
If you know other good rat removal companies, please kindly follow with your comments.