How can I cut this roof?

Hey everyone,
I am having difficulty cutting this curved eve into a roof. I was able to use the solid subtract tool to cut away the other 2 curves in the roof on the low side, and a simple rectangle and push/pull to cut out the other section.
After using the solid- subtract tool, the roof structure was no longer a ‘solid’ even though it appeared that all the faces had been closed during the subtracting process.
I have created this curved white piece that i created using the top of the curved wall and the offset tool, thinking that I would again create a solid face, push/pull it through the roof, and then solid-subtract it away from the roof, leaving a curve in the eve.
But this time, neither the roof or my ‘cutting’ object are solids.
I am also very new, and have greatly struggled with subtracting/cutting material away from faces, objects, etc. and often times end up ‘rigging’ it in a very sloppy way, that ultimately creates or deletes geometry that shoots me in the foot later. Doh!