I'm renovating a concrete block house and the walls have been stripped of the old plaster. The window returns are pretty coarse and rough - not smoothe at all. I'm trying to figure out how best to finish the window returns so that they are smoothe. Complicating things is that the existing aluminum windows have a very narrow frame (maybe 1/2") so any solution has to take this into account. If I nail a furring strip to the inside of the return and fasten 1/2" drywall to that it will completely cover the window frame.
I have no experience with plaster so I'm leary of trying to re-plaster the window returns back to the way they were. I thought about glueing green board to the block but I know there needs to be an air space between the two materials.
What's the best material to use to smoothe out and finish the returns? It must be able to stick to concrete block