Back in 2010, when we were planning a haunted attraction that never came to be, The Nightmare Express, I did some costing on various options of fire retardants and treatments. Below is my data and my conclusion on what ended up being the most cost effective options.
Update 2019, we have switched to using Master Flame for pretty much all applications, since we can spray it, and also use it as our paint mix in.
Flame stop, Christopher Obal http://www.flamestop.com/
Flame stop, Christopher Obal http://www.flamestop.com/
Flame stop 1, cloth “b”, 1500-2000sf/5gal 5gal = $190
Flame stop 2, wood “a”, 125sf/gal 55gal = $1333.33
Flame stop 3, latex paint additive “b”, 1pt/gal $28.99/pt?
1000 4×8 double sided = 64;000sf = 512 gal = $13,333.30
100 gallons of paint = 100pt = $2899.00
Universal fire shield, Bill http://www.firechemicals.com/
F2000 cloth 300sf/gal $52.95 $239.75/5gal 2 coats
FK-100 wood 1gal=200sf @2coats $288.95 5gal
LPA-202 latex paint additive 1gal = 8gal $322.50/ 5gal
1000 4 x8 double sided = 64,000sf = 320 gal = $17,853.80
100 gallons of paint = 13gal = $974.00
New york fire shield http://www.nyfs.com/
Inspectashield cloth 400sf/gal
Wood 300sf/gal $1229.25 55gal
1000 4×8 double side 64;000 sf 213gal $4917
Final Conclusions: Treat plywood and walls with Inspectashield from NYFS and treat all paint with LPA-202 from Universal Fire Shield.