The simplest insulation for the do-it-yourselfer is probably fiberglass batts with a vapor barrier. New “no-itch” fiberglass products make the job less hassle. Exterior walls and cathedral ceilings can be insulated with rigid foam insulation.
You may want to insulate up to R-40. You can check the recommended insulation levels here (popup window will open).
Wear protective gloves and masks.
When installing insulation in the attic, a vapor barrier must be present on the warm side of insulation to prevent moisture problems. The attic must also be properly ventilated.
When installing multiple layers, puncture the vapor barriers on the upper layers.
Don’t squeeze the batts to fit - compressed the insulation has no insulating value.
Get into all the small spaces and corners.
Don’t open the batts until you are ready. It is compressed at the factory and may expand 500% when opened.
Split the insulation partially when covering wires or it will not expand fully and will leave a gap behind the wire.
Install insulation between the rafters of the attic floor, not the ceiling, unless the attic is used as living space.
Install new batts at a 90 degree angle to any existing batts to minimize gaps.
Recessed lights or fans that protrude into the attic space should not be covered by insulation and insulation should not cover vents or louvers.
With cellulose loose-fill insulation check that it is fire retardant.
Sources:
Public housing energy conservation clearinghouse
Ask the Builder
Installing Insulation – Tips for Do-It-Yourselfers
Attic Insulation: Pre-preparation
