Im in the proces of renovating my porch. The ceiling is plasterboard and has been painted. It is open to the air but not exposed directly to rain, snow etc. My intention was to put a thin coat of render on the ceiling which is actualy on a 45 degree angle and then paint it. I rendered it yesterday but it took so long to go off to rub it up that i decided to scratch it and do another coat of something later but start earlier in the day. I dont really want to put another coat of render over it bearing in mind the weight so wondered if one coat plaster would be ok and paint it once dry. The other thing is the ceiling has curves top and bottom so thinking it wil be easier doing them in plaster.