What is insulation payback?

[The Dutchman]

I purchased a house not to long ago.  While I was doing renovations I noticed that the brick walls (all but the back addition) have no insulation within the studs.  Apparently the space between the brick and the stud wall, coupled with the stud wall itself, was thought to be enough of an air barrier to provide insulation.  That was the theory years ago.  Anyway, we now know that insulation within the studs can really help things out. 

I solicited a quote to blow in cellulose and I am getting another one of two quotes (blow in and expanding foam).  Right now the numbers look like 3k to insulate the walls.  I have a ranch which is full height brick around 80% of the house (20% is where the addition juts out). 

Anyone have any experience with this to figure out the pay off?  I think I can get $250 in rebates from the gas company and 10% cost of material in the form of tax rebates (maybe $150).  So the adjusted cost is 2.6k. 

My issue is that I only plan on living here for 5 years then I will be moving and renting it out.  Insulation isn't the sexiest selling point for renters.  So it may not be worth the investment. 

Input requested... Thanks in advance guys. 

PS - I will be insulating the rim joist this weekend which is like a $50 dollar project and will help a ton.  My buddy did it in his house and could immediately feel the difference in his basement and first floor temp. 

[cynthia1848]

What have your heating and cooling bills been like?

Just as a comparison, we insulated our roof in the winter about 6 months after we moved in.  There had been no insulation in the roof.  We also have a brick house (but bigger, 2 story colonial).  Our heating bills went from $800/month in the winter to about $300/month.  So it was a substantial savings.  I think it also cost us about $3K and paid for itself in 2 years (only counting the 3 coldest months of the year).

[Greg]

Here in the PNW cellulose is not considered the best option, it's a mold disaster waiting to happen number one.  Also, it settles.  In my remodel experience, I've seen settling as much as 2" in stud bays in as little as ten years.

Blow-in fiberglass would be a better option.

But, what is the moisture barrier between the brick and insulation going to be?  Unless the brick is painted this could be a problem.  Spray foam usually provides its own moisture barrier.  If the studs are all exposed you will want to design a moisture/vapor barrier into your plans.  If not you might have to wing it.

Renters are aware, or can be educated about, the utility bill benefits of good insulation.