Attic Cleanup After Rodents —
Truckee’s HEPA Protocol — Not a Broom and a Shop Vac
Attic cleanup in Truckee is not optional maintenance — it is a health protocol. Deer mouse droppings carry Sin Nombre hantavirus at a 38% fatality rate. A standard shop vacuum aerosolizes dried particles. A broom sweeps them into the air. In a Sierra Nevada attic above 1,200 meters elevation, you need P100 respiratory protection, HEPA filtration, bleach pre-treatment, and enzyme deodorizer. Here is exactly what that looks like and why every component is required.
⚠️ Sierra County confirmed an HPS death in 2024. Two Mono County HPS deaths confirmed early 2025. CDPH documents ~3 Sin Nombre HPS cases/year statewide at 38% fatality rate concentrated in Sierra Nevada above 1,200m. Truckee is at 1,774m. Standard shop vacuums are not safe for this work.
Why Truckee Attic Cleanup Is Different From Anywhere Else in California
The specific risk that makes Truckee attic cleanup categorically different from lower-elevation California: deer mice (Peromyscus maniculatus) are the dominant attic species at Truckee’s 5,820-foot elevation, and they shed Sin Nombre hantavirus in their droppings, urine, and nesting material. The primary documented transmission mechanism is inhalation of aerosolized particles from dried material in enclosed spaces. The 2012 Yosemite National Park outbreak (10 cases, 3 deaths) occurred from accumulated deer mouse droppings in tent cabin wall voids being disturbed during normal occupancy — no deliberate cleaning required.
A March 2025 study in Ecosphere (NEON data, 2014–2019) confirmed Pe. maniculatus has the highest hantavirus seroprevalence of any nationally monitored rodent species. CDC research documented 26.8% antibody prevalence in deer mice near Sierra Nevada human HPS case sites versus 9.5% baseline — prevalence increases above 1,200 meters elevation. Truckee is at 1,774 meters. This context is why the CDPH cleanup protocol exists and why no substitute is acceptable in Sierra Nevada attics.
The CDPH Attic Cleanup Protocol — Step by Step
Step 1: P100 Respirator Before Attic Entry — Not an N95 Dust Mask
P100 filtration provides 99.97% efficiency at 0.3 microns — the particle size range that includes aerosolized hantavirus-bearing particles. The respirator must have a metal nose piece shaped to your bridge and no air gaps at the seal. Every technician entering a Truckee attic that may contain deer mouse droppings wears P100 respiratory protection before the hatch is opened. Nitrile gloves throughout.
Step 2: 10% Bleach Pre-Treatment — Before Any Disturbance
10% bleach solution (approximately 1.5 cups household bleach per gallon of water) applied to all visible droppings and the surrounding area before any material is physically disturbed. Minimum 5-minute contact time. The bleach pre-treatment begins viral inactivation before particles can be disturbed and aerosolized. Skipping this step and going directly to vacuuming — even with a HEPA vacuum — increases aerosolization risk during the disturbance phase.
Step 3: HEPA-Filtered Vacuum — Not a Standard Shop Vacuum
HEPA-filtered vacuums capture particles at 99.97% efficiency at 0.3 microns and exhaust filtered air. Standard shop vacuums exhaust unfiltered air — they capture the visible debris while aerosolizing fine particles including potentially viral material back into the attic space. The distinction is absolute: HEPA-filtered vacuum for all surface removal in Sierra Nevada attics where deer mouse presence is possible.
Step 4: Enzyme Deodorizer — Breaks the Annual Return Cycle
Enzyme deodorizer applied to all confirmed grease run zones and nesting areas after physical removal breaks down the pheromone scent compounds that persist in attic insulation and on rafter surfaces after animals are gone. A cleaned attic without enzyme treatment still chemically signals “established territory” to new deer mice probing the roofline in September. Enzyme treatment is what breaks the annual return cycle at the chemical level — not optional maintenance.
Step 5: Insulation Assessment — R-38 Title 24 Standard for Truckee
California Title 24 requires R-38 minimum insulation for attic spaces in Truckee’s climate zone (Zone 16). After rodent contamination, insulation compression from nesting activity, urine saturation, and dropping accumulation can reduce R-value by 30–50% before contamination is visible from the surface. We measure insulation depth and use a moisture meter to assess saturation levels in contaminated zones — and recommend zone replacement when R-value is materially compromised.
Step 6: HVAC Off During Cleanup — Prevents Duct Distribution
The HVAC system is turned off for the 2–3 hour duration of attic cleanup. HVAC airflow through the building can distribute fine aerosolized particles from cleanup activity into living spaces through the duct system. Turning the system off for the cleanup window eliminates this distribution pathway. This is the only ask during the cleanup phase — children and pets can remain in the living areas.
When Attic Cleanup Is Required vs. Recommended
🔴 Required — Full HEPA Protocol
- Any visible droppings on attic insulation in a Sierra Nevada property above 1,200m elevation
- Any nesting material found in an attic where deer mice are the probable or confirmed species
- Any attic accessed without respiratory protection during prior inspections
- Properties vacant for a full Truckee winter in forest-edge neighborhoods
🟡 Standard Hygiene Acceptable
- House mouse-only activity confirmed at kitchen/ground level — no attic evidence
- Norway rat crawlspace activity without attic involvement
- Properties where exclusion has been confirmed complete for 12+ months with no new attic evidence
What the Close-Out Report Includes After Attic Cleanup
📸 Before/After Photo Documentation
Photos of attic condition before cleanup (dropping distribution, nesting locations, insulation surface condition) and after (cleaned surfaces, treated zones, insulation assessment) — organized by GPS coordinate for each attic zone.
📏 Insulation Assessment
Moisture meter readings in contaminated zones, estimated depth at assessment points, and specific insulation replacement recommendations if R-38 Title 24 standard is materially compromised by nesting compression or urine saturation.
⚡ Wiring Damage Notation
Any gnaw damage to visible electrical wiring is photographed, located, and noted in the report with a recommendation for licensed electrician follow-up. Gnawed wiring in an attic surrounded by fiberglass insulation is a documented fire risk.
🏠 STR/Airbnb Host Format
Close-out reports are formatted for Airbnb and Vrbo host documentation purposes — a dated professional cleanup report with before/after photos is the documented evidence for platform case management processes when a guest files a complaint.
Frequently Asked Questions — Attic Cleanup Truckee CA
Can I clean the attic myself if I found some droppings in my Truckee cabin?
For a Sierra Nevada property at Truckee’s elevation: if the droppings could be from deer mice (any attic at 5,820 feet is within the documented hantavirus risk zone), professional HEPA cleanup is the appropriate standard. If you proceed yourself: P100 or N95 respirator properly fitted, nitrile gloves, 10% bleach solution pre-treatment before touching any material, HEPA vacuum only, double-bag all waste. Never dry sweep. Never use a standard shop vacuum. For any attic with significant dropping accumulation, nesting material throughout the insulation, or contamination across multiple zones — professional cleanup is warranted.
What does attic cleanup cost in Truckee CA in 2026?
Attic HEPA cleanup: $400–$1,800 depending on scope of contamination, attic access complexity, and insulation assessment findings. A small clean-up of a recently-infested cabin (limited dropping accumulation, no significant nesting) runs $400–$600. A full winter of colony establishment in a Tahoe Donner A-frame — multiple nesting zones, significant dropping accumulation throughout the insulation depth — runs $900–$1,800. Insulation replacement, if required to meet R-38 Title 24 standard, is separate scope: $2,500–$5,000+ depending on attic size.
Does attic cleanup need to happen before or after exclusion sealing?
After exclusion sealing — specifically after the 72-hour zero-catch confirmation that all animals are out. The correct sequence: complete trapping → 72-hour zero-catch → exclusion sealing → attic cleanup + enzyme deodorizer → close-out report. The enzyme deodorizer applied after cleanup is the step that breaks the pheromone recruitment signal for future deer mice — it needs to be applied to a cleared and sealed space to be effective.
Is insulation replacement always required after rodent activity in a Truckee attic?
No — we assess rather than assume. Moisture meter readings and visible contamination assessment determine whether replacement is required. Localized contamination in one zone with intact R-value in surrounding areas may require spot treatment and enzyme application rather than full replacement. We document the assessment findings and provide a specific recommendation based on actual conditions.
Schedule Attic Cleanup — Same or Next Day
P100 respirator · HEPA vacuum · Enzyme deodorizer · GPS photo report
Rodent Shield Truckee
(530) 414-7500 · hello@rodentcontroltruckee.com