It is one of the larger numbers on a wildlife invoice, so it is worth understanding how the decision is actually made rather than taking it on trust.
When replacement is clearly justified
Widespread droppings and urine saturation through the material. Insulation is porous and holds both, along with the pheromone scent that attracts the next animal.
A raccoon latrine, which is a health matter rather than a cleanliness one.
Bat guano accumulation, for the same reason.
Insulation compressed flat into runways and tunnels across large areas, because compressed material has lost most of its thermal value regardless of contamination.
When it is not
A single localised nest with clean insulation around it. Spot removal and treatment of that area is usually enough.
A short occupancy caught early, where droppings are limited and confined.
Anyone quoting a full attic replacement for a two-week mouse problem is worth a second opinion.
What the work involves
Containment and removal of the old material, usually vacuumed out rather than handled loose. Sanitising and antimicrobial treatment of the exposed deck and framing. Odour and pheromone neutralising. Then new insulation blown to the correct depth for the climate zone.
Exclusion sealing should happen in the same window. Restoring an attic without closing the entry points is money spent twice, and we would rather say so up front.
The energy return
Damaged insulation that has been tunnelled, compressed and nested in is performing well below its rated value. Restoring correct depth restores that performance, and people commonly notice the difference in heating and cooling costs.
It does not make the job free, but it does mean part of it comes back.
Insurance
Attic restoration after wildlife damage is one of the more commonly covered items on a homeowner policy, though it varies considerably by carrier and by how the damage is characterised.
Photographs before, during and after, plus a written scope with line items, are what a claim needs. We provide that as standard whether you intend to file or not.