Pasadena, the San Gabriel Valley and the foothills
Rodent exclusion in Pasadena
Craftsman housing stock a century old, deep foothill exposure to the Angeles National Forest, and post-fire displacement pressure across the whole corridor.
37
ZIP codes covered
5
Species we identify
100%
Direct employees
Written
Record every job
Why rodent pressure in Pasadena works the way it does
This is the only one of our service areas east of the 101, and it is different from the rest in three ways that matter.
The first is the housing. Pasadena and Altadena carry an unusual concentration of 1900s to 1920s Craftsman construction, with deep overhanging eaves, exposed rafter tails, knee braces and decorative gable vents. That is entry geometry that post-war tract housing simply does not have, and it sits at a height that ground-level inspection never reaches. It is also frequently in a landmark district, which means the sealing has to satisfy a design review as well as keep a rat out.
The second is that basements exist here. Across most of Los Angeles the question is crawl space or slab. In the older Pasadena and South Pasadena stock a genuine basement or partial cellar is common, with window wells, its own venting and below-grade penetrations. Norway rats rather than roof rats are the usual finding in them.
The third is the foothills. Altadena, Sierra Madre and La Canada back onto the Angeles National Forest, and the 2025 Eaton fire corridor runs through this service area. Displacement pressure moved into surrounding neighbourhoods within weeks of the fire and has not returned to its previous baseline. We regularly see properties with twenty-year clean records reporting sudden first-time activity, and the structure is not what changed.
Rodent species found around Pasadena
Identification comes before any material is chosen, because the response differs by species and the record has to say which one we found.
| Species | Here | Where we find it |
|---|---|---|
| Roof rat Rattus rattus (opens Wikipedia in a new tab) |
Dominant | Citrus, avocado and mature street canopy across the older Pasadena and Altadena streets. The primary residential finding. |
| Norway rat Rattus norvegicus (opens Wikipedia in a new tab) |
Common | Present along the Arroyo Seco corridor, the older storm drain network and the commercial blocks through Old Pasadena and Alhambra. |
| Dusky-footed woodrat Neotoma fuscipes (opens Wikipedia in a new tab) |
Foothills | Native, and common on properties backing onto the Angeles National Forest through Altadena, Sierra Madre and La Canada. |
| California ground squirrel Otospermophilus beecheyi (opens Wikipedia in a new tab) |
Foothills | Burrowing in slopes and flood control embankments along the foothill edge. |
| House mouse Mus musculus (opens Wikipedia in a new tab) |
Common | Standard across the older housing stock, particularly in basements and detached garages. |
Where they get in around Pasadena
Craftsman construction
Pasadena and Altadena carry an unusual density of 1900s to 1920s Craftsman homes. Deep overhanging eaves, open rafter tails, knee braces and decorative vents create entry geometry that later construction simply does not have.
Basements and cellars
Unlike most of Los Angeles, a meaningful share of the older stock here has a genuine basement or partial cellar. That is a below-grade space with its own venting, penetrations and access failures.
Foothill wildland interface
Altadena, Sierra Madre and La Canada back directly onto the Angeles National Forest. Continuous pressure, native species, and post-fire displacement all concentrate along this line.
Post-fire displacement
The 2025 Eaton fire corridor runs through this service area. Displaced populations moved into surrounding neighbourhoods within weeks, and properties untouched by fire have seen sustained pressure since.
Arroyo Seco corridor
The arroyo and its flood control infrastructure give Norway rats a continuous below-grade travel route through the middle of the service area.
Original attic venting
Decorative gable and eave vents on century-old homes were rarely built with screening that survives, and where they have been rescreened it is often with material that has since corroded.
Seasonal pattern across the year
Late summer
Fruit ripens across the older Pasadena and Altadena streets, and roof rat populations climb with the food supply.
Autumn
Attic activity calls spike as nights cool. On Craftsman stock the entry is usually at eave or rafter-tail level.
Winter rains
Arroyo and flood control burrows flood, pushing Norway rats toward basements and below-grade spaces.
Post-fire windows
Displacement pressure follows fire activity in the corridor by roughly two to three weeks, independent of season, and the 2025 corridor is still producing elevated activity.
Jobs the Pasadena crew has worked
Three properties from this service area, described at neighbourhood level rather than by address.
Bungalow Heaven
1912 Craftsman- The call
- Attic noise and a homeowner who had already had two contractors out.
- What the inspection found
- Entry at three open rafter tails under the deep front eave, plus a decorative gable vent whose original screening had gone entirely. Both prior contractors had worked at ground level and never got a ladder up to the eave detail.
- What we did
- Rafter tails closed with material matched to the visible woodwork, gable vent rescreened in a way that preserved the original appearance. On historic stock the sealing has to survive a design review as well as a rat.
Altadena
foothill property near the burn corridor- The call
- Sudden onset of activity in a home with no prior history in twenty years of ownership.
- What the inspection found
- Post-fire displacement. Nothing about the structure had changed. The pressure had. Entry at a crawl space vent and a gap at a utility penetration, both long-standing and previously untested by anything.
- What we did
- Sealed both, and documented the displacement context in writing so the owner understood why a twenty-year clean record ended abruptly. Placed on a retainer given the corridor exposure.
South Pasadena
1920s home with a partial basement- The call
- Damp smell and droppings on the basement stairs.
- What the inspection found
- Norway rats, entering below grade through a failed basement window well and an unsealed sewer lateral. No roofline involvement at all, which is unusual for this area and worth noting.
- What we did
- Window well rebuilt and screened, lateral packed and capped. The basement is the defining feature of this housing stock and it needs a different inspection from a crawl space.
ZIP codes covered from Pasadena
37 ZIP codes within roughly 45 minutes of 1446 E Walnut St. If your address is not listed, call and ask, another office may cover you.
Pasadena
- 91101 Pasadena
- 91103 Pasadena
- 91104 Pasadena
- 91105 Pasadena
- 91106 Pasadena
- 91107 Pasadena
Foothill communities
- 91001 Altadena
- 91011 La Canada Flintridge
- 91024 Sierra Madre
- 91214 La Crescenta
- 91020 Montrose
Glendale and Burbank
- 91201 Glendale
- 91202 Glendale
- 91203 Glendale
- 91204 Glendale
- 91205 Glendale
- 91206 Glendale
- 91207 Glendale
- 91208 Glendale
- 91501 Burbank
- 91502 Burbank
- 91504 Burbank
- 91505 Burbank
- 91506 Burbank
San Gabriel Valley
- 91030 South Pasadena
- 91108 San Marino
- 91775 San Gabriel
- 91776 San Gabriel
- 91801 Alhambra
- 91803 Alhambra
- 91006 Arcadia
- 91007 Arcadia
- 91016 Monrovia
- 91010 Duarte
Northeast Los Angeles
- 90041 Eagle Rock
- 90042 Highland Park
- 90065 Glassell Park
Questions we get from Pasadena callers
My house is a historic Craftsman. Will sealing ruin the look?
It should not, and on this stock that is part of the job. Rafter tails, knee braces and decorative vents can be closed with material matched to the visible woodwork, and gable vents rescreened while preserving their appearance. If your property is in a landmark district, tell us at the inspection so the scope accounts for it.
We had no rodent problem for twenty years and now we do. Why?
In this service area the most common answer is displacement. The 2025 Eaton fire corridor runs through here, and populations pushed into surrounding neighbourhoods within weeks. Nothing about your structure changed. The pressure did, and long-standing gaps that were never tested are now being found.
I have a basement rather than a crawl space. Is that different?
Yes, and it is one of the few parts of Los Angeles where this comes up regularly. A basement has window wells, its own venting and below-grade penetrations that a crawl space does not. It needs a different inspection, and Norway rats rather than roof rats are the usual finding down there.
We back onto the forest. Does exclusion actually work?
Your structure can be made unavailable, which is the honest claim. We cannot reduce the population in the Angeles National Forest and would not pretend to. Foothill properties along this line are the ones where we most often recommend a retainer, because the adjacent habitat never empties out.
Services available from this office
See all fifteen on the services page.
Book an inspection in Pasadena.
Tell us the property type and where you first found evidence. The Pasadena crew will confirm your earliest available window.
(323) 968-0181 · 1446 E Walnut St, Pasadena, CA 91106