Can I install kraft faced product over existing kraft faced material?
No, it is not recommended to install insulation with a kraf facing over another. When installing layers of insulation, there should only be one vapor retarder installed in the appropriate location. It is not good practice to incorporate two vapor retarders in an insulation system. Moisture could become trapped between the two layers and not be able to dry.
Can the kraft facing be left exposed?
Kraft facing should not be left exposed. For insulation material to be left exposed, building codes require the surface of the material to have a flame spread index of 25 or less. Insulation with kraft facing does not have the required flame spread index and must be covered by an appropriated material like drywall.
Can you install fiberglass blowing insulation over cellulose or visa versa?
Fiberglass installs at a lighter weight than cellulose. Therefore, fiberglass can be blown on top of cellulose without the threat of compressing the existing insulation. Since cellulose must be installed at a much higher density or weight, it cannot be installed on top of fiberglass due to the potential to compress the existing insulation.
Do I get the same R-value if the product is compressed into a cavity?
When fiberglass batt insulation is compressed, the R-value per inch is increased, but the overall R-value is decreased because there is less inches or thickness of insulation.

Learn more about R-Value here: https://www.knaufnorthamerica.com/r-value
Does insulation really help with sound movement?
Yes, the installation of fiberglass insulation delivers excellent sound absorption. Sound insulation significantly reduces noise between rooms and from external sources.

Is fiberglass fire proof?
Fiberglass is not considered fire proof. However, unfaced fiberglass insulation batts are noncombustible per ASTM E136 and can be used where noncombustible insulation is allowed. It requires no additional first-retardant chemical treatments. Be aware: the addition of facings may change this rating. Therefore, refer to the manufacturer’s technical data for each product for specific surface burning characteristics. 
Fiberglass insulation products manufactured by Knauf Insulation have surface burning characteristics of a flame spread index of 25 or less and a smoke developed index of 50 or less, which meets all national building and mechanical codes for insulation. 
Discover Knauf Inner Safe Concealed Batt Insulation (https://www.knaufinsulation.us/en/content/new-inner-safe-concealed-space-batt-knauf-insulation-provides-code-compliant-alternative) that is a fire code compliant alternative.

Learn more about insulation fire protection: https://insulationinstitute.org/im-a-homeowner/about-insulation/health-safety
Is kraft faced material required on interior walls?
No, kraft faced insulation is not usually necessary for insulating internal walls. A kraft facing is a vapor retarder which helps prevent mold caused by moisture in unconditioned air. For exterior walls, exterior basement walls, attics, and roofdecks, the insulation should be pressed in the wall cavity without compressing it and the paper side facing outward (towards the installer).

Learn more about insulating wall cavities here.
What is an ice dam?
An ice dam is ice that forms on the roof that stops melting snow from draining properly. A lack of sufficient insulation in a home can cause heat to disperse, melt the snow on a roof and create ice dams. Ice dams have been known to push water into cracks within homes, causing potentially devastating water damage.
What is k value?
The K-value measures the amount of heat needed for the insulation to change the temperature one degree hotter or colder. The K-value is more commonly used in a professional or commercial insulation industry.
What is r value?
The R-value measures the thickness of the insulation and resistance to heat flow. The higher the R-value the better the insulation.

Learn more about insulation r-value: https://www.knaufnorthamerica.com/r-value
What is u value?
The U-value measures the thermal resistance of a building. The sum of all potential areas that when heated can easily turn into a cold space. The lower the U-value the better the potential of the building to contain heat.