Insulating attics, roofs and exterior walls are the primary ways to reduce energy costs. However, there is something to be said for the axiom "if a little is good, a lot is better," and insulating interior walls can make rooms more comfortable, further enhance energy savings and help to deaden sound travelling through the home. Insulating interior walls can be done with either batt or blown in insulation, depending on the access to the wall cavity.
Decide if you are going to use batt or blown-in insulation. If the interior walls are already finished with drywall or plaster, blowing the insulation is the less intrusive option. If you are replacing th e drywall or the home is a new construction without drywall in place, you can install batts of insulation between the studs.
Install batt insulation by unrolling the batt, cutting it to length with a razor knife and placing it in the wall cavity. The paper facing will have flaps that overlap the studs and can be stapled in place to secure it.
Drill 2-inch holes through the interior finish to access the wall cavities if you are using blown insulation. Use a drill with a 2-inch hole saw bit. It is best to drill the holes as high as possible to utilise gravity when filling the cavity. To lay out the spots to drill, measure from the edge or corner of the wall. Studs will be placed on 16-inch centres and you will want to drill between them.
Insert the nozzle of the blow machine into the drilled holes and turn on the blow machine. It's helpful to have a helper turn the machine on and off and to feed insulation material into the machine's hopper.
Fill the cavity with insulation. When the machine feels back pressure, it will begin to labour and you will know that the cavity is full. Be mindful of the interior finish. If the drywall is not installed correctly or if it is damaged, the pressure from the insulation may cause it to pop.
Turn off the machine and move to the next cavity. Repeat the process of filling the wall cavity with insulation. When all cavities are filled, repair the holes with insulation plugs, drywall patch or plaster, depending on the existing finish.
Always wear eye protection, gloves and suitable clothing when working with insulation. Insulation fibres can be harmful if inhaled and can cause eye and skin irritation. In insulation cavities with electrical wiring, switches or fixtures you should have a qualified electrician verify that everything is in working order. Fibreglass insulation will not ignite, but it can melt from high heat.