NavMeshBounds for Slope Check

Hi,
I am currently playing around with an RTS setup. My current state allows me to place buildings. Now i would like to implement a slope check which should prevent placing a building on a great landscape angle. I know that i can do line traces but then i thought about the NavMeshBoundsVolume. Is there a possibility to get data from it which areas are “blocked” and which are not and use this information when trying to place a building (spawn an actor)?