1.1 vs. 1.38
most of the tarps we discuss are made from 1.1 sil nylon...barring cuben and spinn.
There is some gray area here. The fabric starts its life as 1.1 oz/sq. yd.
Then it is silicone impregnated, thus giving it 1.38 oz weight (approx)
Some vendors call it 1.1, some list it as 1.38. But typically it is the same thing.
The next step upwards in weight is poly urethane (PU) coated fabric. Normally a 1.9 oz. fabric and then urethane coated, making it weigh close to 3.0 oz. per yard.
Fire and lightweight fabrics don't get along. Can't do much there for ya. Other than keep the fire away. A small cookstove fire under the tarp has been done plenty. Take care to keep the fire small and contained.
Ambulo tua ambulo.