I am currently working with parcel data and a raster slope analysis in % change I created with DEM data. I symbolized the slope analysis discrete 0-2.5%, 2.5-5%, 5-7%, 7-12%, 12+% and overlayed it with my parcel data. I want the parcels to have a "Buildable Area" attribute calculated by subtracting the raster area that has values of 12+% from the parcels. I also have a wetlands polygon layer and I was able to subtract from the polygon area.
How do I do the same with raster?
This is in QGIS.