Here are some guidelines.
Old brown attic insulation.
Believe it or not there are situations in a home when you should remove the old attic insulation before adding more over the existing and in this short video.
Brown insulation is available in either blanket rigid foam board or loose fill form.
The particles of the insulation have an accordion like texture.
Dirty attic insulation on the other hand could have been the result of pests like rodents and birds that contaminated the insulation which can lead to an unhealthy home.
If either of these situations are the case it s time to remove insulation.
Brown insulation is made up of mineral wool which comes from either rock natural materials or slag the scum on the surface of molten metal.
It is made from a natural mineral material that is mined from the earth.
If the insulation particles have a certain colour usually grey brown or silver gold.
If the insulation lays flat.
Department of energy notes that 75 percent of mineral wool is derived from post industrial content.
If your home was built before 1990 chances are you have one of the old attic insulation types.
Vermiculite insulation has a pebble like appearance and typically is a grayish brown or silvery gold color.