Quick opinions please, on the first ability of Sculpt Flame, that is the Double Area of flame (assuming combustibles available) [page 175 core book]

Does this mean that the existing flame can be doubled onto an area that may not be combustible (eg concrete) as long as the existing flame has sufficient fuel ? of does both the existing flame and the area it is to be doubled to must both have sufficient fuel ? (eg; burning car in a Forrest)

The exact situation is a Sorcerer using this power wanted to double the flame on a burning vehicle to the surrounding area which was 100% all concrete.

Thanks in Advance

Yes, as the psyker is directly using warp power to fuel the flames, enhance them, and blow things up.

On the other hand, no he's simply enhancing the natural combustibility of something. Obviously, concrete is not combustible.

On top of this, it should be immensely obvious the psyker is doing this, such as instantaneous and uniform expansion of the flames, unnatural color and/or behaviour of the flames.

Quick answer- yea, its raw warp power, however there should be "consequences".