How To Apply Stucco

Stucco is one of the oldest, most durable and most versatile exterior home treatments available. It comes in many colors and can be applied glass smooth, popcorn bumpy or any texture in between. The three-step application process demands a bit of do-it-yourself savvy, but with practice, you can get professional results without paying professional prices.

Stucco has been used since the days of ancient Rome, though the ingredients, which often included things like animal blood or urine, beeswax, eggs and rye whiskey, have been given a healthy overhaul. Modern stucco is made of Portland cement, hydrated lime, sand and water.

Stucco will adhere to almost any type of masonry, as long as it's not painted or sealed to keep it from absorbing water. It can also be applied to wood, whether painted or not, but this requires first attaching lath, which is a sturdy metal mesh.

If you're applying stucco to masonry walls, you'll need either 15-pound roofing felt or paper-backed lath, metal shears, nails appropriate to your walls and a nail gun. You'll also need a large bucket or tub to mix the stucco and the tools to apply it.

The first tool is a large, flat trowel to apply the scratch or base coat. The second is a scratcher, which looks like a very wide comb. Next is the double-handled darby, which is a long, slender trowel used to smooth the brown coat. Finally, you'll need a hawk and trowel. A hawk serves the same purpose as an artist's palette. It holds small amounts of stucco for you to trowel on and make your designs, if any, in the finish coat. It also helps to have several helpers to ensure that the stucco doesn't dry before you can cover the entire wall.

Brush all dirt and debris off of your surface with a sturdy brush or broom. You can also use a power washer as long as the exterior treatment of your home can handle that without damage. Patch any cracks, if necessary. If you're applying stucco to brick, cement block or existing stucco walls, you must keep the walls damp with a mister.

If you're applying the stucco to a painted or wooden surface, you need to apply lath to the wall. Using paper-backed 17-gauge self-furred lath will save you the step of attaching roofing felt first. Measure carefully and then use your metal shears or a circular saw to cut the lath to fit the wall in large panels. Do one side of the wall, then the other and then the center. Attach the lath with the proper nails at 18-inch intervals.

Mix your stucco according to the manufacturer's instructions. Work in small batches so that it doesn't have a chance to dry out and harden. Apply the stucco by swiping it onto the lath in a layer that's approximately 3/8-inch thick. Once the entire wall is covered, drag the scratcher across it in horizontal lines. This will help the next coat adhere better.

Stucco needs to cure for 24 to 48 hours between each coat. Once the base, or scratch, coat has cured, you can apply the brown coat. This is done the same way you did the scratcher coat – just trowel the stucco on as smoothly as possible in a 3/8-inch layer. Instead of scratching it, you'll use a darby to smooth it out completely.

Many DIYers skip this step, but it does make your stucco stronger and more durable. Let it cure for 24 to 48 hours and then apply the finish coat with a hawk and trowel. Decide on your design preference ahead of time and practice on scrap wood until you're proficient. Apply the stucco design of your choice and let it cure for 24 to 48 hours.

Stucco will last between 50 and 80 years if it's applied properly and cared for. Patch any cracks immediately and keep your stucco free of mildew and mold, especially where your walls come in contact with plant matter or severe dampness. Don't pressure wash stucco as it can crumble.