I love it personally, ever since it was started to be widely used over 20 years ago. The major problem is that it makes homes so tight that you just need to have a fresh air intake from outside, to replace the inside air and circulate it. FRom what I have seen its not that expensive any more. Even the house I bought 3 years ago here in Central Florida has foam blown into the blocks.

Saw it done in Florida. Kept the attic temperature to under 70 degrees as opposed to over 100 for traditional insulation. Simply amazing!

I have had clients rave about it - their heating and cooling bills are drastically reduced and it even provides an amazing sound barrier. I don't know how long to recoup the cost though - it's fairly expensive.

This is a picture of one of my listings with Icynene. They have it in the attic and crawl as well.

Never heard that it was that expensive to do. You would think that more people would care about it.

I just sold a 60 yr old home that only had 4" insulation in the attic. How a negative R value there!

It's a common method used here.... I'm not sure about the downside.... I have rolled fiberglass batts.... 

Interesting question.  This is definitely above my pay grade but I will check back to see the responses of others with experience/knowledge.  Maybe one of the home inspectors/contractors will provide information/opinion.  

You have many answers here.

Homes need to breathe. I would not do it on our house. Radiant heat barrier might be better, or look at the ways they do it when building log homes with exposed beams.

Parked and viewing answers.

In my area they will foam walls but have not seen it in attics. The foam in the walls seals air around windows, doors and outlets which sounds like a good application to lower energy costs.

   I like the photo from Debe Maxwell, CRS 

We just use it for the small spaces and cracks.

They do this here in AZ. I'd have to ask our home inspector to get his ideas on the quality and longevity.

I looked into it and opted for a radiant barrier instead.  You can buy the foam spray at Lowes and Home Depot, but it is pretty pricey and you have to do it all quickly otherwise the nozzle can clog (they do sell it with several nozzles though).  It's not a bad option at all and one I would have considered but I already had the barrier purchased (I was looking to do the underside of the roof).

I haven't seen it in this area yet, but I did have one client who did his walls. I love concept, but the long term challenges that future renovation contractors will face are huge. For instance, if you want to add a receptacle on a wall. It's not impossible to get one in a foamed wall, but it's difficult and expensive. So, there are up and down sides to using foam.

In Florida it is advantageous as it helps bond the roof sheathing to the trusses and reduces roof failures in high winds. In addition, the evidence I have seen is the temperature differential is much higher vesus the ambient air temperature.

I agree with Wayne Martin.  It would have been a great help in our atic at our home in Napa during the summer, and winter.  Our AC bill was $600 a month during the hottest months. A 

I know nothing about costs or recouping costs on energy bill savings.  I do not that is it done in my area.  Not very common ... rolled batts are more the norm ... and what I have in my attic.  

Never heard of it. Insulation salespeople should work harder to get the awareness up.

It sounds like a viable option if the price is right but you would have to ensure the home is breathing. I'm always cautious about new technology because there may be problems we just haven't thought about yet.

Parked and reading...

I have not seen its use much here in South Florida, still common here is the pink fiberglass. 

Other than the the use of some Great Stuff expanding foam I haven't got a clue except I have heard there are sometimes condensation issues.

Haven't really thought about this, so will see how others resond.

I haven't seen that in my city.

Have a new home under contract and saw a home down the street getting this foam, and was pretty interesting to watch! 

I don't know.

Do not know anything about it in the Denver area on foaming.

Peter Mohylsky - I see this as a 'new' trend in our market area. It seems it is preferable method!

WEll making sure there is ventalation it the biggest downfall

I'm so glad to see all the answers here!

Peter Mohylsky 

I have a spread sheet that I have developed and refined over the years. It translates to hours of running the furnace and cost of running with what ifs. In a nutshell, R19 is not adequate for attic. The easiest way to reduce utility bill is add another layer. I hired a test consultant and we fixed a -major leak around the furnace(cost is $9.50) and I ordered 6 rolls of R13 fibreglass.  It probably broke even first year. I also discovered ground floor warming in the winter to raise floor temperature.

As far as using polyurethane insulation, it is close cell structure. When in contact with moisture, condensate soaks up act like a sponge. The person who started it years ago went back to fiberglas type in his cold region home. He was credited for inventing the foam on thin wall insulation. People inhale release agent used in the process some get sick. 

The city offered to pay and we accepted. Excellent as it helps to cool & heat

The only thing is the vents need to remain clear. I have not seen it around here

An interesting question. And, you have some interesting answers.

Not heavily used in our area

No idea