In my opinion it is not worth the $8500 investment. You are already at R19 for the walls, and R50 for the attic. These are above average insulation values. Adding additional foam seems like overkill for SE PA.

If you assumed a yearly cost of $2000 to heat and cool your home, and a 20% reduction in cost by adding the insulation, then yearly savings would be $400. It would take over 20 years to recover your investment.

Mike home,
Your analysis is almost right in line with what I did. I took last years bills (I'm anal.. I keep everything recorded) and went month by month separating heating and cooling. I assume my cooling will be similar (same electric, bigger house, but more efficient heat pump and R19 instead of R13). I assume my heating will be similar as well (bigger house, wood a bit more expensive than gas, but R19 instead of R13).

My avg. bill (was gas, now wood or heatpump so more expensive) AND my new home is 3K+ compared to 2K sq ft. BUT it's 2x6 and much better insulated.

So I think my bills will likely be a bit higher due to bigger house but not too much higher due to the R19 and R50.

In my old house, last year's bills were 250 a month so let's say 3000 a year. Using a 20% decrease in costs (just due to spray foam) gives me 600 a year so the breakeven is only 14 years. But if it's 30%, then the breakeven is only 9 years. So % what to use... ??

But, who is to say what my new bills would be WITHOUT the spray foam AND what they would then be reduced by WITH the spray foam. I usually love analyzing things like this but it's very frustrating when there are too many UNKNOWN VARIABLES. Know what I mean?

Thanks!

Did you look at the calculator @ sprayfoamdirect?

Taking the kit cost as the material cost, you could figure out if you're being robbed.

Here is a link that might be useful: Spray foam direct

I replied in building forum.

still think you'll never get builder to add foam
sheathing to exterior of walls..which is the
best upgrade..including foam spray in walls.

instead put the foam in the roofline for an
unvented semi conditioned attic.
the sun hits the roof all day this is our biggest
heat gain.

but when bidding the foam for the roofline
understand that you only need foam over
the conditined space. use felt paper or
foam sheathing to close off over porches & garage
then foam can be installed to make the seal air tight.
make sure they bid for sq ft of living space
& understand not to foam over porches & garage.

best of luck.

if you have a bedroom over a garage it might be worth spray foaming that particular area.

Do some research on foam before you make a decision. I had read about several bad things about the foam itself. I has its drawbacks beyond the initial cost.

Yesterday I told the $8500 spray foam was out of my budget and I'd pass. Later in the day, he came back and suggested doing a rockwool type product. He also mentioned they could spray a wet cellulose (open not closed) product about 2-4 inches thick, then they'd add some kind of insulation to that. It would likely be about half the cost of the spray foam, and still do a decent job. It should get me about R21 and provide better air flow reduction than just R19 fiberglass. He was still gathering ideas from the insulation guy, so it was a bit unclear.
So I looked up rock wool (mineral wool), which looks pretty cool compared to fiberglass. Rigid (not flimsy), fits tight into bays, cuts easily without crushing it etc. But it doesn't look like it gets blown in (or can it?), so I have to check with builder to see exactly what he is proposing.

I like the concept of doing 2,3,4 inches of wet cellulose since it seems it will close up (I know not as good as spray foam would) any of those little gaps that I was hoping spray foam would get.

Both cellulose and rock wool seem to have slightly higher R values than fiberglass from what I've researched.

Thoughts on this new approach of cellulose and/or rockwool, since I simply can't afford the spray foam?

UPDATE:
I ended up calling in 3 different insulation guys for ideas and pricing. I basically had them price out various options.. fill bay with open cell cellulose, fill 2" of closed cell sprayfoam then R15, fill bay with open cell sprayfoam etc.

One price was near the builder's proposal, but the other 2 were thousands less.. literally. I ended up agreeing to have one guy (highly rated, straight A on Angies list, good references, in business for decades) spray 2" of closed cell spray foam for about $5300. With R15 batts over that, I should be pretty tight. He also said he would foam the basement rim joists for a couple hundred more which I think would be worth it.

So, we'll see how it turns out, but I'm glad I shopped around and the builder was cool with that.

Thanks for everyone's advice.

Have you calculated your return on investment on the $5300 foam insulation? If so can you share it with us?

That's a tough one, since I don't, nor do most people I see who mention ROI, have good variables with this. I am an analyst to the core, but quite frankly nobody can tell me for sure what my monthly heating/cooling bill will be WITH the sprayfoam and what it will be WITHOUT it.

I've asked the HVAC guys, the York guys, the insulation guys (all 4 of them), and NONE could give me a good analysis to show the true savings.

I've seen spray foam "cuts bills by 20%!" or "saves up to 40% on monthly bills" etc. but nobody ever backs up those figures. e.g. just google "savings from sprayfoam" and you'll see.. "The US Department of Energy (DOE) studies show that 40% of your homeâÂÂs energy is lost due to air infiltration" OR

"Monthly energy and utility savings of 30% or greater can be achieved when compared to the alternative roofing and insulation systems. The cost of an SPF roof or insulation system can often be recovered in less than 5 years, simply through energy savings alone."

But no figures ever back that up. SO, I set up a simple spreadsheet in Excel, with inputs of 1. Monthly utilities without sprayfoam 2. Expected savings and 3. Sprayfoam cost.

It allows me to input different variables and see results. My situation is especially tough b/c the house is new and I don't have any "current" utility bills. But what I did have was use my old house bills, which admittedly was smaller, had 2x4 framing, and was no doubt not as tight. But I had my old bills and then added on some increased costs to account for the larger 3200 vs 2000 square feet, and the increase due to TYPE of utility.. going from natural gas to electric heatpump and propane (3x the price of the NG I used to have). The tough thing is knowing how much of those utility bills are heating/cooling vs. lights/dryer/water heater etc. (things that won't get affected by sprayfoam).

So I assumed I'd have around $350 in monthly (average heating/cooling) costs, and assumed I'd save 20% due to sprayfoam. That is $70 a month. For a year, that's $840 a year. $5300/840 = 6 years or so ROI. Using a 30% savings led to a 4 year ROI. Using 10% led to a 12 year ROI.

Furthermore, assuming a lower $300 monthly utilities, the ROI is.. 10% = 15 years 20%= 7 years 30% = 5 years Assuming $250, its 17 years, 9 years, 6 years.

Knowing that I plan to be in this house for 20+ years, and that I expect utility costs to go up faster than inflation, for me, the cost made sense.

I would expect your annual heating and cooling bill would not be greater than $2500 given the construction and size of your house. I think the foam insulation may save 15% on energy costs. So the savings would be in the range of $375 per year. This would mean a pay back period of about 14 years.

Natural gas prices have dropped significantly during the past three years. I can now heat my 3200 sq. ft. house for $450 a year and I don't have as much insulation as you do. Hopefully the cost of electricity will plateau and fall when inflation is factored in.

I personally would have put the $5300 towards a better HVAC system. A better system is more comfortable and saves money at the same time.

Mike_home,
Appreciate the feedback.

I see your point about the HVAC upgrade instead. But my rationale is that HVAC upgrade is something I could do later (in fact I plan to do 2 zones next year) but the sprayfoam is just one of those things that CAN'T be done later without MAJOR cost and damage to home.

I see your analysis based on your assumed $2500 for the year, but quite frankly, I think our scenario is a bit different than many, and thus our bills will likely be higher.

Why? First, my wife is always cold in the winter. She keeps the heat cranked UP (or tries to.. haha) so our bills are higher than average. Our GAS bill for our old home approached $200 in the winter months (compared to $25 during summertime..hot water, dryer). And that was us in a much smaller home, with only heating 3 bedrooms (now 4) and me being very vigilant with always keeping the thermostat lower than she preferred. And even though the home was older, I had an energy audit done a few years back, and had really tightened up the home over the past couple years (foaming all accessible areas, laying down an additional layer of attic insulation, etc. So, I'd expect heating (even with the 2x6 R19 fiberglass we could have used) for our new home would be a fair bit higher than the $200.

Furthermore, we both work from home most of the week. So where we used to (and many people can) lower the thermostat during the day to save big bucks, we simply can't. Our heat/cool will run much more than the average person.

Also, my wife hates bugs so the sprayfoam will be huge on keeping them out. Is not seeing bugs worth 5K? Heck no, but it's just one added bonus.

Also, is the complete unknown about fuel prices. Could they stabilize? Sure? Would they go down? I doubt it. If anything I see them rising so the sprayfoam gives me some confidence that I can hedge that.

So those are small caveats that I need to keep in mind.

It will be an interesting venture. I will no doubt post an update next year with my thoughts.