Roof rats in the attic: what actually works

Scratching overhead at 2 a.m. is one of the most common calls we get. Trapping is step three, not step one.

Roof rats are excellent climbers and terrible houseguests. They come in overhead, not at ground level, which is why so many rodent jobs get handled backwards.

How they got in

A roof rat needs a gap the size of a quarter. In Valley homes the usual entries are:

• Where the garage roof meets the main wall
• Unscreened or chewed attic and gable vents
• Gaps around the sewer vent stack boot
• Tile roof edges with missing bird stop
• Utility line entries that were never sealed

They do not tunnel in. They walk in, usually from a tree branch or a fence line, and they use the same route every night.

Why traps alone never finish the job

Traps kill the rats currently in the attic. That is real progress and it stops the noise. But the route is still open, and roof rats broadcast that route through scent trails. New rats find it within weeks.

We have followed behind plenty of jobs where somebody trapped nine rats over two months and never touched the two-inch gap at the roofline. The population reset every winter.

The order that works

1. 1Inspection: find every entry, not just the obvious one
2. 2Exclusion: seal with hardware cloth, sheet metal, and mortar where needed
3. 3Trapping: remove what is now sealed inside
4. 4Sanitation: droppings and nest material, plus a look at insulation damage
5. 5Monitoring: exterior stations and follow-up checks

Sealing before trapping sounds backwards to people. It is not. A sealed attic with six rats inside is a solvable problem. An open attic with six rats inside is a subscription.

What you can do yourself right now

Cut every branch back at least three feet from the roof. Rats are good climbers but they are not great jumpers, and that one change eliminates a huge share of access.

Then walk the perimeter at dusk with a flashlight and look for rub marks. Rats leave greasy dark smudges on the surfaces they travel over repeatedly. Those smudges tell you exactly where the highway is.

When to call

If you hear running or scratching overhead after dark, especially between September and February, do not wait for spring. Attic populations grow fast and the insulation and wiring damage adds up.