Insulation Removal in San Mateo, CA

Local Context

What Roof Rats Leave in a Sunnybrae Attic Outlasts the Trapping

Rodent contamination is not a smell you can wait out. Roof rats (Rattus rattus) nest in blown-in attic insulation, compressing runways through it and depositing urine and droppings continuously along those paths. In San Mateo the attics hit hardest sit in the older neighborhoods where the street-tree canopy reaches the roof — San Mateo Park, Baywood, the blocks around Central Park — because that canopy is how the rats got up there to begin with.

Contaminated insulation also stops working as insulation. Compressed material loses loft, and loft is what the R-value depends on, so an attic that met the standard in 1965 may be well under it now. Add moisture — a roof leak, a bath fan venting into the attic instead of through the roof, or condensation in the humid conditions common on the bayshore side near Marina Lagoon — and the material mats down, holds water against framing, and starts feeding wood-decay fungi.

There is a health reason to do this with equipment rather than a shop vac and a dust mask. Dried rodent urine and feces can carry hantavirus and Leptospira bacteria, and disturbing contaminated insulation puts exactly those particles into the air of a hot, poorly ventilated space. Removal runs on HEPA-filtered vacuum equipment and protective gear, followed by disinfection of the deck and framing underneath.