Abstract: An accurate method and apparatus for installing blown-in-place insulation to a predetermined density and R-value includes the use of a removable container of known unfilled weight and volume located between wall studs during the blowing operation. By removal of the container after filled, and determining its fill weight by weighing it, the density of the insulation is calculated and correlated, if desired, to R-value. If the calculated density is not acceptable, the container is emptied and is reinserted in the cleaned out cavity between the studs. Appropriate adjustments to one or more operating parameters are made until the desired density through further filling of the container and weighing it is achieved. Once achieved, the space to be filled is filled with blown-in-place insulation using the adjusted parameter values.