Previously I discussed how much insulation should you add to your ceiling or attic, now I would like to discuss how to get the most benefit from your installation. If the insulation is not installed correctly you will have wasted your time and your money and you will not realize much energy savings.
A couple of items to consider, I will not go into great detail here, but you need to be aware of a few potential pitfalls:
1) If you have recessed lighting, e.g. can lights, make sure they are IC-Rated (Insulation Contact). If they are not IC-rated, insulation must be kept at least 3 inches from the housing of the lighting. This can be accomplished with a surround for blown in insulation or cutting the insulation short of the fixture if using blanket batts.
2) Do not cover venting in the attic. Typically there are soffit vents that allow air to enter the lower part of the attic and escape through ridge vents in the roof. These must be kept open and clear to maintain a healthy, energy efficient attic.
3) If there are any openings that should be sealed. Spend some time chalking those openings before you install the insulation. Stopping air leakage will save you a great amount of energy costs. Once all of the openings and recessed fixtures are protected you are ready to start installing insulation.
The two most common types are fiberglass or cellulose. Fiberglass and cellulose can be blown in. Fiberglass also has the option of laying in blanket batts. Both products have a similar R-value. The advantage to blowing in insulation is it is easier to fill in tight areas and around trusses, pipes and wires that may be running through the attic. It is probably a faster process than cutting in batts. But you need to have physical barriers to keep the insulation out of places that need to be left open. Also it is a good idea to place marks on the trusses at the depth you want the insulation, that way you do not need to crawl through the insulation to measure the depth.
Some drawbacks are that the insulation may settle over time and lose some R-value. Also you must rent a machine to blow in the loose fill insulation. This process can create a lot of dust throughout the rest of your house. If you are laying blanket batts, make sure they are unfaced. Any moisture barrier on the insulation could lead to moisture condensation and eventual mold and mildew. Next, if there is already insulation between the trusses, you want to run the batts at right angles to the joists.
Make sure the batts fit tight against each other and you neatly cut around all pipes, boards and wires (slice the batt to fit around the wire rather than compressing it under the wire), etc. The insulation needs to fit snug against everything so there are no spaces, but don’t compress the insulation or you will greatly diminish its R-value and not slow down heat loss in those areas. Start on the edges and work your way in toward the more open areas. Make a plan on how you will work your way out of the attic, don’t “paint yourself into a corner.” Take your time and in a day’s time you will end up with a professional job that will save you money for years to come.