Things You'll Need
Concrete bonding agent
1 1/2-inch roofing nails
Wheelbarrow or cement mixer
Tabby is a historic form of wall plaster that utilizes oyster shells to create a mottled texture. Tabby wall finishes that were added before the invention of cement are extremely fragile and needed frequent reapplication. Today, with the addition of cement, tabby is applied as stucco for more durable and long lasting results. Many masonry and stucco suppliers sell oyster shells for tabby stucco.
Dig a trench along the bottom of the walls, if you are applying stucco all the way to the ground.
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Prepare the walls. If the walls are brick or block, clean the walls with concrete cleaner, using a pressure washer. Once dry, paint the walls with a concrete bonding agent. Allow the bonding agent to dry.
If the walls are wood, nail lathe stops at all the points that the stucco will end, such as where the wall meets the foundation, using 1 1/2-inch roofing nails. A lathe stop is a flanged metal strip that will contain the stucco. To go around a corner, the lathe stop can be snipped with tin snips and bent. Nail flashing over the top ledges of windows and doors to promote water runoff. Staple building paper to the walls, using a staple gun. Nail metal lath to the walls, affixing the nails at the corners so the nail heads catch the wire intersections. Place nails approximately every 14 to 16 inches horizontally and every 6 to 8 inches vertically.
Create your scratch coat stucco. In a cement mixer or wheelbarrow, mix together 1 part lime, 2 parts cement and 3 parts sand. Mix thoroughly and gradually add just enough water to make a thick, mortar mix. Mix for at least 20 minutes.
Apply an approximately 3/8-inch thick layer of scratch coat stucco to the walls, using a trowel. Apply firm pressure. Start from the bottom and work your way up. Smooth the first coat with a concrete float, working in circular motions. Allow the first coat to cure for a few hours until it starts to harden. Scratch the entire surface before it completely hardens, using a plasterer's rake. Allow the scratch coat to dry for 2 to 3 days. Mist the scratch coat occasionally with water to ensure it does not dry out too fast.
Make the tabby stucco topcoat. In a cement mixer or wheelbarrow, mix together 1 part lime, 2 parts cement and 3 parts sand. Mix thoroughly and gradually add just enough water to make a thick, mortar mix. Mix for at least 20 minutes. Add the oyster shells towards the end of the mixing. Add them gradually until you see them consistently distributed in the stucco.
Apply a layer of the tabby stucco to the walls, using a trowel. The layer should be about as thick as the oyster shells. Apply firm pressure. Start from the bottom and work your way up. Once finished, mist the stucco occasionally over the course of 5 to 7 days while it is curing.