Thank you for your support. But it's clearer for me if you can compare different cost by liter because there are several kinds of chemicals in mixture formula.
For example, if I set price of TC-3FRND = THB 10 / liter, how much will it be if we change to TC-3AFR? (How much does the cost different?)
My idea is to save cost of roof insulation by changing FR chemical because the market price is very cheap. That's all.