If your home is a “freezer” during the colder months and an “oven” during the hot months, then your house is not properly insulated. Older homes are often not well insulated especially those with cavity walls. More often than not, older cavity walls do not have insulation at all. Warm air seeps out from the interior through cold spots while hot air seeps in from outside through cold spots too. This has an effect on your heating and cooling bills making your home energy-inefficient.
The best way to insulate older homes with cavity walls and unfinished attics is by loose-fill insulation. Materials such as cellulose, fiberglass or rock wool can be used as insulation to increase the energy-efficiency of your home. Proper insulation will dramatically decrease your energy bill.
How to Install Blow-in Insulation in Cavity Walls
Find the studs on the cavity walls and mark them. Use a pencil and make the mark about 6 inches below the ceiling line. Make sure you mark all the locations of the studs.
Drill a hole between the stud marks. The span of cavity wall in between studs should have a hole with a diameter of 1 ½ inch for dense packing or 2″ for simple blow in fill. Note that every cavity wall that requires insulation need to have a hole for the insulation machine hose. Be VERY careful not to drill into a duct.
If the holes are drilled, you can now set up the insulation machine. You might want to set it up outside if your holes are on the inside walls. Place the insulation machine’s nozzle into each hole. Make sure the nozzle is snug to avoid the cellulose from blowing back. Wrap a rag around the nozzle if it’s loose. Have your helper fill up the hopper with cellulose then turn on the machine. Once the bay is filled with insulation, the insulation machine will stop blowing the cellulose with the machine sounding like its struggling. You will feel resistance from the hose and when you do, the wall cavity bay is already filled. Turn off the machine and move on to the next bay.
Once all the cavity walls are filled with insulation, you are now ready to seal the holes. You can use plugs or an expandable foam filler spray to close the hole. Remove any excess foam to make the wall flush. Apply putty on the wall then finish with a touch-up paint job.