A homeowners survival guide to eliminating animal infestation in your attic

Signs Of Animal Infestation In Your Attic

Most homeowners discover mice, squirrels, or raccoons by hearing noises in the attic, finding stains on the ceiling of the living space, or smelling a foul odor coming from the attic (especially on hot Chicago summer days.) . You may find little droppings, urine, or food supplies such as acorns, seeds, etc. 

To remedy the animals in your attic you should get several estimates, review multiple opinions, and treatment ideas before taking action. 

Common Questions Of Attic Infestation

Common questions asked by homeowners during the estimating process for animal infestation are 

  • How much will it cost? 

  • Does my homeowners insurance cover costs? 

  • should we have all the insulation removed first? 

  • Is the existing insulation deemed unusable? 

  • will the insulation smell if we leave it in place after disinfection? 

  • Do I need to leave my home during the remediation treatment portion? 

  • What is the difference between fiberglass insulation and cellulose insulation? 

  • Does cellulose insulation get mineral treatment to prevent pests? 

Detecting Animal Infestation
Detecting Animal Infestation

Weatherproofing / Entry Points

To ensure animal infestation is stopped, a sealed exterior building envelope is crucial.  The building envelope is where mice, bugs, squirrels, raccoons, and more enter. Think of eliminating their entry points first.

Sealing the building envelope and eliminating entry points for mice and bugs will also keep the house snug and tight, making it easier to control interior temperatures and humidity.

 A sealed home will shield against heat and cold, and provide a clean controlled environment. 

Mice in particular can fit through very small gaps so minding the gaps of the building envelope is crucial to preventing intrusion. 

7 Expert Ideas To Combat Animal Infestation

  1. Air sealing the attic floor to prevent mice from reaching the attic floor by sealing the penetrations around vent stacks, HVAC, plumbing and electrical penetrations, and framing gaps while the attic floor may be sealed after attic treatment, the mice will still nest in the walls, basement and crawl space if the exterior penetrations are not treated * step 7 
  2. Removing feces / droppings with high powered vacuum while leaving the existing insulation in the attic
  3. Disinfecting the entire attic to neutralize odors and kill bacteria ( similar to cleaning a rug from dog or cat urine )
  4. Providing baffles for ventilation  in every joist bay and a vapor barrier top plate to baffle dam to prevent blown in insulation from clogging the soffits 
  5. Blowing in premium class 1 borate treated cellulose which is rodent resistant
  6. Insulate air air seal hatch cover or pull down ladder 
  7. Seal exterior penetrations in the building envelope using a local contractor ( painter, handyman, or pest control service with exterior air sealing experience.) Mice in particular can fit through very small gaps so minding the gaps of the building envelope is crucial to preventing intrusion. 
Animal Infestation In Attic Insulation
Animal Infestation In Attic Insulation

Animals in Attics

Common animals native to Illinois such as deer, bobcats, turkeys, and more will not be found in attics, however mice, squirrels, and raccoons are quite common.  Mice will leave small quarter sized holes / tunnels in the fiberglass insulation, small brown/ black droppings and urine. While squirrels and raccoons will leave much larger feces as well as food supply shells such as acorns and walnuts.  

Animals leave trails through the insulation and compress retreaded sections causing lower R-Value and compromised thermal barriers. This old insulation is now damaged and full of feces and urine. 

Cost For Infestation Remediation 

You may find when receiving multiple quotes for animal infestation cleanup, they vary dramatically in both cost and treatment plan line items, warranty, and performance for comfort and efficiency.  Green Attic provides an itemized proposal with square footage of treatment as the predominant factor in calculating cost. Other factors include accessibility to and from attic, location and type of attic entry, existing insulation materials, debris and more. 

On average disinfection is between $1-2, removal of existing insulation between $1-2, air sealing attic floor, installing complete ventilation, and insulation to optimal R-60 between $3-5 per sq ft which includes air sealing, baffles ( air chutes / rafter vents) and a proper hatch cover.

Does Homeowners Insurance Cover costs? 

Most homeowners insurance policies may offer coverage for “acts of nature” but rarely do mice, squirrels, raccoons, and bugs fall into the covered category. Occasionally, if a raccoon does damage to the exterior soffits to gain entry, an insurance claim may be needed to supplement the cost of repairs. In most cases, your insurance policy will not cover mice in attics, and the attic project would be recommended for changes despite the infestation, to shield the home against heat and cold.

Should The Existing Insulation Be Completely Removed?  

  1. If the existing insulation is damaged by feces and urine it can be disinfected, similar to the process of cleaning pet urine on carpet. If the insulation is compressed, disturbed, and generally just moved around, it can be disinfected and remain in the attic after treatment providing a base layer for the new insulation to be blown over the top.   
  2. If the insulation is infected  and compromised it can be vacuumed out first before providing new insulation. 

Insulation Damage Due To Animal Infestation


  1. A critter / animal discovery from hearing noises on the overhead drywall may be a blessing in disguise ( an opportunity to address bigger issues such as heat escape, moisture, mold, or mildew. )  
  2. Basic animal infestation cleanup in the attic is around $1.9 to$2.5 per square foot; this does not include new insulation.  
  3. Prevent bugs, pests, and animals from getting into your home by evaluating and sealing the exterior building envelope. 
  4. Add a new layer of clean fresh borate treated cellulose insulation to prevent nesting. 

Contact us today for a free estimate and begin the process of creating a clean healthy home environment. Take advantage of  our true and tried best approach for a healthy comfortable home. Solve attic problems like mice where critters enjoy proximity to food, shelter and warmth.  Eliminate icicles, reduce heating and cooling costs, ensure a complete moisture thermal and pressure barrier for your attic space in the process. . 

Call Green Attic 847-777-4777 to schedule a free estimate.

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