Sprayed fireproofing as additional wall mass?

Hi, Has anyone had any experience using spray applied fireproofing as additional mass in a wall system? I spray fireproofing as my day job and have never seen any official numbers as to how effective this would be as part of a m-a-m system. Sound transfer "seems" to drop after spraying the walls of a building and the fireproofing we spray does have high mass and density. But this is absolutely unscientific and untested. The specific product I am referring to is Cafco Blazeshield II link: http://www.isolatek.com/product_search.asp?productID=51 This product is much denser and heavier than blow-in wall insulation such as cellulose or fiberglass. Hypothetically: 1st Leaf- Garage with stud walls,sheathing,exterior finish. Sealed with caulking and sprayed with 2-3" of fireproofing between the studs from the inside. -air spring stuffed with fiberglass- 2nd Leaf- Double drywall stud wall (room within room construction) also sprayed with 2-3" of fireproofing. Any thoughts on this? If no testing has been done with fireproofing would it be worth doing some testing? I could do some basic testing (have a test mic, software, and an spl meter as well) if there is interest or opinion this may be worth pursuing. If I go ahead with testing,I would be open to suggestions as to how I set it up for the most usable results. Caveat: I would not test with a big structure. The test structure would have to be done as panels, sprayed on a job site, brought home in the back of my truck, assembled at home, tested. Open to all comments or suggestions. Thanks, Steve

Your product specifications read 15 pcf/240 kg/m3 which is a little less than >1/3< the density of typical gypsum sheetrock. Sheetrock numbers taken from this page: viewtopic.php?p=51414 Thanks and good luck, Brien

Thanks for the response. So realistically drywall is probably a better option. For me personally, because I have access to fireproofing cheaply, I may augment my walls with it on top of the drywall. For the record, I am not affiliated with Cafco, I just spray the stuff. Any thoughts on why it might be detrimental to do this? Or a wasted effort? Thanks for any opinions, Steve

I am very familiar with spray fireproofing products - work on projects that utilize them quite often. My only concern would be on relating to long term bonding between the fireproofing and the sub-strate it is applied to. These products are designed to be applied to either raw structural steel or to galvanized steel decking - not to drywall or plywood. I would feel pretty confident stating that there have never been any long term studies done (as regards bonding to materials on other than steel) - and would not feel anywhere near confident as to taking the experiment on myself. Sincerely, Rod

Cold wrote:

If no testing has been done with fireproofing would it be worth doing some testing? I could do some basic testing (have a test mic, software, and an spl meter as well) if there is interest or opinion this may be worth pursuing. If I go ahead with testing,I would be open to suggestions as to how I set it up for the most usable results. Caveat: I would not test with a big structure. The test structure would have to be done as panels, sprayed on a job site, brought home in the back of my truck, assembled at home, tested.

Testing this yourself would be less than useless..... and I am not trying to be either funny nor insulting. Testing labs have special rooms set up - with special openings - in order to perform testing of this nature. They know the limitations of their existing assemblies - know exactly when flanking begins to affect the readings........ at which point they have gone as far as they can. You obviously are not a testing lab. If you really want to know - then make up a sample and pay to have it tested at a real lab - otherwise don't waste your time..... the results really will be meaningless. Rod

Thanks Rod for responding, Fair enough on the testing comments. I'm not looking for a make work project so I won't try and self test. Don't worry about hurting any feelings, I work on job sites spraying fireproofing, I've got thick skin. As for long term bond, in my professional opinion, the material bonds incredibly well to any porous non oily substrate, but, you are absolutely correct, I do not believe any long term studies have been done. I will double check Astm studies when I get a chance. Could always apply metal lathe before spray which is a time tested method for questionable substrate, but this starts getting into the question of how much effort is justified for untested and questionable results? Thanks again for your input. Steve

Forgot to thank you Rod for creating such an important book. Steve