Exterior doors are heavy and can be awkward to move – you’ll usually find it easier to paint them in place instead of trying to take them off their hinges. However, removing the doorknob and latch bolt makes the job a whole lot faster and neater.
With the door upright, you’ll have to be aware of catching drips and runs. Work one small, defined area at a time and try not to overload your paintbrush. Make sure all six sides are covered to protect your door from rotting, cracking and expanding.
First, apply paint to the inside of the top panels. Smooth out the paint, working with the grain, doing the recessed areas first, then the faces of the panels.
If the door has a vertical center stile, paint this next, and then blend in the brush marks from the center stile when you paint the horizontal rails.
Paint the rails (horizontal framing members), starting with the top rail and working your way to the bottom.
Paint the remaining vertical stiles, starting on the left. Feather the brush marks from the rails while they are still wet. Keep the line as straight as possible along the edge where the stiles meet the rails. Brush or roll the edges, but be careful not to get any runs on the face of the door.