2005 nissian altima floor panels

[bollinger660]

i am a mechanic at a used car lot and we took in a 05 altima and the passenger floor pan was rotted out completely. i have seen this about 3 other times and we were able to give them back to the auction. this one we own. i am going to plasma cut the floor pan out and weld another piece in my question is what thickness do you think i should use and what can i use to keep the carpet and padding from catching fire?