Volume Extraction Problem (no ceiling building)

[20-1-01423]

hi, im using loft tool for the roof. Ive tried the surface loft (wont work in volume) and the 3d model in lofting in spaceclaim

but when im doing a volume extraction it only read the volume floor - upto - the roof surface level (3d Model) (pic attached). or i dont need to use volume extraction no more?, i can just go with the enclosure?

can u help me please

my study is to simulate fluid flow from outside - inside - outside
thank youuuu

note: the surface there is the ground, volume 1 (walls), volume 2 (roof - pyramid like)