How to Make Outside Plaster Walls

Staple waterproof membrane to a wood-sheathed wall using a construction stapler. Secure lath with a hammer and galvanized nails driven into the studs behind the sheathing. Put a "weep screed" of perforated metal at the bottom to allow any moisture to escape.

Mix a "scratch coat" of stucco according to the manufacturer’s instructions. Dampen the masonry wall with water slightly. Spread a 3/8-inch base, or the "scratch coat," of plaster stucco over the wall using a rectangular mason's trowel, pressing it firmly into the metal lath. Scratch horizontal lines into the plaster once it has begun to set up, using the notched side of the trowel. Let this coat cure 48 hours, keeping it slightly moist with water during the curing.

Mix a "brown coat" of stucco according to the manufacturer’s instructions. Dampen the masonry wall with water slightly. Lay a second coat, or the "brown" coat, over the base using the flat trowel. Spread this coat also about 3/8-inch thick. Smooth it once the wall is covered by pulling a long, straight board down from top to bottom. Remove the excess material at the bottom. Let it cure 24 hours.

Mix a "finish coat" of stucco according to the manufacturer’s instructions. Spread the 1/8-inch thick "finish coat" using either the rectangular trowel or a pointed mason's trowel. Add any desired texture by varying the depth of the plaster slightly; make swirls with a trowel or create dimples or popcorn effect by pulling plaster up and then troweling down the peaks. Let this coat cure 24 hours.