Options for insulating the walls of an existing home?

[NickB79]

I'm looking for input from people who have already had it done as to what route is best for insulating the walls of my 1968 rambler. Right now there is no insulation, which means that the walls are freezing to the touch, and on windy days you can feel cold air blowing out of the outlets! Next spring I will be investing money on new windows and siding, and since the siding will be off I wanted to add insulation and put a weather-wrap on the house before putting up the new siding. Right now it appears that finely ground cellulose and expanding foam are the two primary choices, and I don't know which one would function better. The cellulose appears to be cheaper and I can do it myself (we put blow-in cellulose in our attic space last year), but the expanding foam appears to fill and seal better as well as providing another layer of vapor barrier.

My other option, if filling the walls proves too costly, is to just add a layer of rigid-foam insulation over the exterior walls before attaching new siding. While that would probably only get me 1/3 the R-value of the wall-filling, between that and the weather-wrapping it should at least effectively stop all air infiltration.

Any ideas? Thanks!