Happy new year to all!.
ICF home, going to spray icyene on the underside of the roof decking, atic not vented. I am getting two complete opinions from conteractors. Closed cell, off gases to much and completly unhealthy, i won't use it!, I will only use open cell!. Contractor # two, closed cell is all i use, better r-value! So any opinions?. Also, is it needed to blow in anything on the top of the ceiling sheet rock?

                                                       Thanks to all
                                                       E. Jones

Mr. Jones,

I believe Icynene foam is considered an open cell foam.  It is in my opinion a great product for your application.  It is recognized as a great insulation by the American Lung Association, it has no VOCs, and is not a food source for mold and fungus.

If it were me I would listen to contractor #2 since it sounds like he is educated on his product.  You can look up info on Icynen on the website www.icynene.com and look up the brochure http://www.icynene.com/assets/documents/PDFs/ConsumerBrochure.pdf

Good luck

ICF Contractor

If you use a closed cell foam on the underside of the roof and you develop a leak, heaven forbid the closed cell foam can trap the moisture and cause the sheeting to rot.. You will find the problem when you step through the rotten spot. Better to use the open cell for that application, in my opinion.

We just installed icynene in out coastal FLhome project. Open cell. Only way to go. Closed cell for vertical applications.

FlaICF has it right.

Keep in mind the r-value per inch on both systems is different, and yes, closed cell is a higher R, but the use of open cell and the subsequent lack of air infiltration provides much better insulation value than regular batt insulation. Basically, you get a much superior functioning product!

Just curious how many inches of open cell were used for the roof. In my area I believe we have to have an R value of 40. Would one have to use around 12 inches of foam to pass inspection or am I missing something?

Thanks

Usually the required R value is based on whole house performance such as wjen you use ResCheck.
The applied R value of sprayed foam is more efficient than other forms of insulation, however, even if you do need r40, the "calculated measure" r40 of sprayed products and the in-place performance is different.
In general, the sprayed product performs better than it's so-called calculated measurement simply due to such low or zero air infiltration!

Ejones,
Icyene is indeed "open" cell foam. It will pass water through if a leak develops above it, although the water may travel a long way before it finally comes out the bottom.
There are "closed" cell foams on the market and they do cost more, they have slightly higher "R" values and they do not pass water. The problem of the sheathing rotting is a real one but any roofer in Florida will tell you that 8 out of 10 roofs they repair have rotten sheating someplace on the roof.
There are also adheasive foam that help hold the roof sheating to the trusses and there are foams that are used to "glue" tile down to a roof. These are more expensive and are not as good at insulating.
We have done a lot of research into the foam business and there is little value in using the closed cell varity in Florida. We routinely insulte our roofs with 4" of Icyene and our attic spaces never exceed 87 degrees in the summer.
Regards,
Joe