Insulation, Radiant and Vapor Barriers - Foam vs Fiberglass Insulation

We are building a new addition and are looking at using a spray-on foam insulation product instead of traditional fiberglass insulation. Does anyone have any experience with such a system? Our primary reason for using it would be for energy efficiency (we live in the NW where temps are below zero in winter and above 100 in summer). The product specs give it an R-7/inch rating. We are also interested in the sound barrier performance. General question is: Is it worth the extra cash?

Id find out what gas does it put out when it burns. some can kill you. thats why I like cellulose insulation best it cant burn or melt like fiberglass insulation does.

ED ;)

By far spray foam is the best. I.m looking in to starting my own business so I'm trying to get all the info I can.

http://www.eere.energy.gov/consumer/your_home/designing_remodeling/index.cfm/mytopic=10090

This is an option that you may want to consider. Furthermore, the most superior foam insulation wall/ceiling are Structural Insulated Panels (SIP's) which this site provides a link to. In fact, you cannot find another site with the amount of links, information, which includes statistical data, on energy efficient building appproaches, practices and methods.

In HOT/HUMID Slidell, LA my neighbor had his ground floor sprayed with foam. (2" over approx 1,400 sq ft for under $2,000. I priced just the cost of 6" of fiberglass for my 1,500 sq ft home at Approx $850 not counting installation cost. Zero cost if you do it yourself. However the proper installation and breathing through a proper face mask in an overhead position is not fun. Factor in that the spraying COMPLETLY SEALS this crawl space floor. No bugs, drafts, or cold floors now(in winter).
Further, these companies claim that by sealing off the attic completely (Close all vents, exhaust fans,etc) and spraying the attic ceiling, the attic temp is maintained no higher than 10 degrees above the living area. So in the summer with temps in the high 90's and humid, you are basically inside a styrofoam cooler. Cost initially is a factor but look what the payback is in saving A/C and Heating costs.
I've checked several websites and one that has a good rating thru the BBB is:
www.greenbeaninsulation.com.

I have'nt used any of these firms YET but would like to hear any pros/cons.
Having lived in the North, ventilation and circulation was/is always impressed, but in the south and with the best of venting and circulating if you have a 100 degree day and a black/dark roof the best/lowest temp that you could hope to have in your attic would be 110 or most likely higher, and the A/C would be going big time I expect.

Further, these companies claim that by sealing off the attic completely (Close all vents, exhaust fans,etc) and spraying the attic ceiling, the attic temp is maintained no higher than 10 degrees above the living area.

Id like to know just what this will do to the plywood roof and the roof shingles up there??????

Ed Ive seen reports from Owens corning that their is only a 6 degree demp increase!

I'd be concerned this creates too tight a vapour barrier.

In my Pacific Northwest climate, we fell into the Pan-American craze for vapour barriers, suffered interior mildew & rust (sick building) as a result, and now have the ridiculous code enforced side-effect solution of automatic venting. In other words, we have to build our houses like moisture-tight thermoses, then to compensate, either mount an exhaust fan on timer (during heating season), or put 8" holes (always open) through the walls - kinda self-defeating isn't it?

My position is to follow the code even in folly. In the case of vapour barrier, I just do the absolute minimum.

I know Cellulose is my new best friend!!! I did my attic and sprayed it in the walls by drilling holes under my lap wood siding!! It worked great!! So far I have noticed a huge difference. I spent 2200 dollars from Novermber of 06 to June of 06!! So far this yr from Nov to now I have spent 1000 and still have a 3/4 tank to go. I have forced oil heat. My windows and doors aren't helping I know. GOOD LUCK!!!

Further, these companies claim that by sealing off the attic completely (Close all vents, exhaust fans,etc) and spraying the attic ceiling, the attic temp is maintained no higher than 10 degrees above the living area.

Id like to know just what this will do to the plywood roof and the roof shingles up there??????

Ed: Thanks for the reply and doubts. I too have/had doubts being from NY where venting is impressed big time. But this 100+ year old two story house in Slidell, LA had NO venting or insulation in the attic whatsoever other than the cracks,or joints in the roof eaves.BOY WAS IT HOT, even in April. The roofing appeared ok including the shingles(approx 9 years old). I started by installing one of two gable vents and 6" of fiberglass on the attic floor, along with soffit vents, then a power exhaust vent in the roof. This is great for the east coast.
Then I saw this company doing my neighbors house in LA. They have an excellent record with the BBB and guarantee their claims. So even with the work I've done so far I'm still very much inclined to do the attic their way. I'll ask them about your/now my concerns re the roof decking and shingles, and will lose the venting, soffits, and fan (close-em up!)
At $1.25/sqft per inch installed(sprayed) , I can't buy it cheaper myself($1.30), then I have to spray it!