Pest control got rid of the rats. The droppings, urine and nesting trails they left in your insulation are still up there — here is what to do about them.
If you live in Houston, you have probably heard something running across the ceiling at 2 a.m. at least once. Roof rats are excellent climbers, and the region’s mild winters, dense tree canopy and overhanging live oak branches give them an easy path onto your roof and into your attic. When the nights start to cool off in the fall, an insulated attic is about the warmest, quietest shelter they can find.
So you called pest control. They set traps, sealed the gaps around the roofline and soffits, and the noise stopped. Problem solved — except for what the rats left behind in the insulation over your head.
Rodents don’t just pass through an attic. They live in it. They tunnel through blown-in fiberglass, shred batts for nesting material, and use the insulation as a toilet for as long as they are up there. That material sits directly above your ceiling drywall, your light fixtures and your return-air grilles, and it does not clean itself.
Rodent droppings, urine and nesting material can carry disease. The CDC’s guidance on cleaning up after rodents is direct about attics: if exposed insulation is contaminated with urine and droppings, it should be placed into plastic bags for removal. Not vacuumed in place, not covered over with a fresh layer — removed.
There is a practical side to this as well. Insulation works by trapping still air in a loose, lofted layer of fibers. Rat traffic packs that layer down into runways, and nesting pulls it apart into clumps and bare spots. A blanket of fiberglass that started at a foot deep can end up crushed to a few inches along the rats’ favorite routes, which means less R-value exactly where your ceiling needs it during a Houston summer.
Then there is the smell. Urine soaks into the fibers and the dust on top of them, and in a 130-degree August attic that odor does not stay put. It drifts down through recessed lights, the attic hatch and gaps around ceiling penetrations. Plenty of homeowners never connect a faint, stale smell in an upstairs bedroom to the attic until someone finally pokes their head through the hatch.
None of this means every attic with a single mouse sighting needs a full tear-out. A short visit through one corner is a very different situation from a colony that lived up there all summer. The point is that the decision should be made by someone who has actually looked, not by guesswork from the hallway.
You don’t have to crawl across the joists to get a good read. With a flashlight from the top of the ladder, look for these three things.
Dark, rice-sized or larger pellets on top of the insulation, along the framing, near the hatch and around ductwork — plus packed-down paths running along the top plates and joists.
Yellowed or darkened patches in the insulation, a sharp ammonia smell, and greasy dark rub marks on the wood where rats have brushed past the same spot hundreds of times.
Burrows dug into blown-in insulation, batts pulled loose or shredded, and places where you can now see drywall or ceiling joists that used to be covered.
If you see any of these, snap a few photos from the ladder and stop there. Digging into the material is the one thing you don’t want to do — which brings us to the shop-vac.
It is tempting to treat this as a weekend project: buy a box of contractor bags, borrow a shop-vac and spend a Saturday in the attic. The CDC’s guidance argues against exactly that. It warns against sweeping or vacuuming rodent urine, droppings or nesting material, because doing so stirs contaminated dust into the air you are breathing.
A household shop-vac makes it worse. It is built for sawdust, not fine fiberglass and contaminated dust, and a lot of what goes into the hose comes right back out the exhaust — into an enclosed attic, with you in it. Add the heat, the crawl across ceiling joists where one wrong step puts a foot through your drywall, and the hours it takes to bag an entire attic floor by hand, and the do-it-yourself savings disappear quickly.
Professional attic insulation removal is done with commercial removal equipment built for the job, not a garage vacuum. The contaminated material comes out of the attic in sealed bags instead of being carried, shaken and swept through your living space, and the crew is equipped for the conditions up there.
The order of operations matters more than most people expect. Get it wrong and you end up paying for the same work twice.
New insulation in an attic that still has an open gap at the roofline is just a fresh nest. Your pest control company should confirm the activity has stopped and the entry points are closed before anything else happens. The CDC makes the same point: trap the rodents and seal them out first, then clean up.
Everything that is soiled comes out. In a lightly affected attic that may be one section. After a long infestation it is usually the whole attic floor, because droppings and urine rarely stay in neat, visible patches.
With the old material gone, the drywall, framing and ductwork are visible for the first time in years. This is the moment to deal with leftover droppings and nests and to disinfect the surfaces using the wet-cleaning method the CDC describes. It is also the best chance you will ever get to spot chewed wiring, crushed ducts or damaged ceiling drywall — rats chew, and attic wiring is one of the things they chew.
Then the attic gets brand-new insulation. For most Houston attics that means blown in attic insulation, which fills in around wiring, framing and ductwork without leaving gaps. Because you are starting from a clean, empty attic floor, it goes in at full, even depth instead of topping up whatever was left.
Nobody wants to pay for an attic cleanout. But there is a real upside: an empty attic floor is the best possible starting point for an insulation upgrade. The Department of Energy recommends R-30 to R-60 in attics in Houston’s climate zone, and plenty of older Houston homes were built with far less — then lost more to settling and years of foot traffic from contractors and critters. When the old layer is coming out anyway, you can go straight to the depth your home should have had all along.
It is also worth asking whether a radiant barrier belongs in the same project. With the attic already open and cleared, adding foil to the roof framing is easy to fold into the same visit, and it tackles the radiant heat that pours off a Houston roof deck every summer afternoon.
Not always. A brief visit through one corner of the attic may leave only a small area to remove and replace. A long-term infestation usually means removing the whole attic floor, because contamination spreads well beyond the spots you can see. The CDC’s guidance is that exposed insulation contaminated with rodent urine and droppings should be bagged and removed.
Not over contaminated material. Covering it traps the droppings, urine and odor under a new layer, where they keep affecting your indoor air and can’t be cleaned later without pulling out both layers.
The CDC advises against sweeping or vacuuming rodent droppings, urine or nesting material because it puts contaminated dust into the air. A household shop-vac also tends to blow fine particles right back out through its exhaust.
Pest control comes first. The rodents need to be gone and the entry points sealed before the insulation comes out, or the new insulation simply becomes the next nest.
Fresh droppings that show up after an area has been cleaned are the clearest sign. Scratching or running sounds at night, new gnaw marks and fresh rub marks along the framing also point to ongoing activity. Your pest control company can confirm the attic is clear before removal is scheduled.
For most Houston attics, blown-in fiberglass installed to the Department of Energy’s recommended R-30 to R-60 range for our climate zone. Because the attic floor is empty, it can go in evenly at full depth from the start.
Your attic assessment and written estimate are free. You’ll get a straight answer on whether you need a spot removal, a full tear-out or nothing at all, plus a clear price for removal and new insulation. Serving Houston, Katy, Sugar Land, The Woodlands, Cypress, Spring, Pearland and the surrounding communities.