Top plates are where the wall meets the ceiling. They are typically not sealed at construction and are a significant source of air leakage in your home. Other gaps that occur at construction include electrical and plumbing penetrations, chimneys, and can lights.
As air escapes from the conditioned space to the attic, the fiberglass insulation is acting as a filter. Evidenced by the dirt and staining on the insulation.
There isn't enough insulation in this attic to keep this home comfortable. It isn't even filling the cavities in the floor, in some places, it is pushed aside completely.
A R-38 of blown-in cellulose insulation is installed after air sealing is completed. The insulation is approximately 85% recycled material and 15% new material. The cellulose we use contains a borate solution that helps deter pests and rodents.
Knee walls are a shared wall between conditioned living space and attic space. They are also a huge source of discomfort in their neighboring conditioned space, which is typically too hot in the summer and too cold in the winter. Properly insulating and air sealing these walls, just like the attic floor, helps make the neighboring room more comfortable year round.
This home had high energy bills, and the homeowner had rooms that were uncomfortable year-round. The existing attic insulation was minimal and dirty, showing it had been acting as a filter for escaping conditioned air. We air sealed the attic to reduce the loss of conditioned air through the attic and installed a new bed of blown-in cellulose insulation. This homeowner is more comfortable in their home and benefit from lower energy bills.