Exterior corners for cement stucco are often best done with the addition of a trim accessory known as a “Corner-Aid” or “Corner-Bead.” This trim accessory can be a welded wire, PVC or expanded metal lath material. Regardless of the material, the trim accessory should be designed specifically for cement stucco and approved by the manufacturer for that usage. Corners may be square or bull-nosed. A PVC nose is recommended for acrylic finish coats and metal nose for cement finish coats.