Safety concerns in insulating an attic vary with the age and condition of the attic being insulated. Safety considerations when installing attic insulation include:
1. Ceiling must be structurally adequate to support weight of new insulation and person(s) accessing the attic.
2. Knob and Tube Electrical Wiring. Always have wiring checked out before insulating over knob and tube wiring. Knob and tube wiring refers to two wires that carry electricity and that run through and are attached to ceramic knobs and tubes rather than the modern one-cable electrical wiring. Generally, do not insulate over active knob and tube wiring unless it can be effectively bridged under/over with a hardboard avoiding any direct contact with the wires.
3. Open Electrical Junction Boxes and/or Exposed Wiring. Junction box covers must be added before insulating. All damaged wiring should be repaired/replaced before insulating.
4. Combustion Air Intake(s). For combustion appliances that require outside combustion air, the supply air may come from the attic space. Do not cover combustion air inlet vents.
5. Existing Insulating Vapor Barrier. If an existing vapor is present with existing insulation, adding an additional vapor barrier over the existing insulation and vapor barrier can trap moisture and create mold problems.
6. Exhaust Ventilation. All exhaust ventilation from bathrooms, kitchen, and utility areas should be vented to the outside. To avoid moisture and mold in the attic, never exhaust directly into the attic.
7. Insulation Clearances. When insulating chimneys, non-insulated rated recessed light fixtures, motors, fans, etc., noncombustible blocking material must be used to create a 3-inch clearance. Block must exceed the height of insulation by 4 inches.
8. Attic Ventilation. If air leaks into the attic from inside the home, or if insulation is placed over soffit vents, moisture problems can develop.
9. Asbestos-Containing Material. Some attics insulated in the late 1970s and early 1980s were installed with vermiculite that may contain asbestos. If your attic has vermiculite, it should either be left alone or inspected and tested for asbestos before proceeding with additional insulation.
10. Respiratory and Skin Protection. Exposure from insulation fibers and particles can be minimized by wearing proper clothing, long-sleeved shirts, safety glasses, gloves, and an N-95 or N-100 air filter mask.
11. Ladder and Fall Safety. Walking in the attic is often not easy and requires stepping from one ceiling joist to another. This can be made easier by placing boards across the joists. Only use ladders of the proper strength and length to accommodate the people making the attic assessment and installing the insulation.
Supporting information from the U.S. Department of Energy: Attic Insulation
