I’m concerned that my contractor doesn’t know what they’re doing with the stucco! They started Friday and just did a little, not even all of one wall, came back the next day and did a tiny bit of a different wall, and no work Sunday. The first layer of stucco, I thought, should be wet-cured - so I’m really confused by what they’re doing. Is it all going to fall apart?
How to stucco to your home’s exterior
The temperature and elements need to be right when applying stucco. If the temperature is too hot, the stucco will dry too quickly and crack or shrink. If it's too cold, the mix will be too thick to properly spread. The ideal weather and temperature for installing stucco is on a cloudy day (not raining) with the temperature between 55° and 80° F.
Stucco is applied in three layers. The first layer is the "scratch" coat, which is the base coat; followed by the "brown" or second coat, which is the leveling coat to ensure the wall will be smooth; and finally the finish coat, which is the layer of stucco you will actually see.
If you're applying stucco to a block, brick or concrete wall, you first need to apply a concrete bonding agent to the walls—then allow it to dry.
If your walls are wood, you first need to ensure they are moisture-proof. Cover the walls with roofing felt or plastic house wrap stapled in place. Be sure to overlap the horizontal seams by at least 6 inches and the vertical seams by at least 2 inches to ensure there are no gaps.
Next, cover the walls with 17-gauge metal mesh held in place with galvanized roofing nails (once again overlapping the seams to ensure total coverage).
After the walls have been prepared, the next step is to apply the "scratch" coat using a trowel to spread a half-inch layer of mortar mix forced down into the wire mesh.
After applying the scratch coat, it should be allowed to dry for a few hours. The surface then needs to be roughened or "scratched" using a scratch tool. You can make your own scratch tool by driving 1.5-inch nails about 1 inch apart through a piece of 1-inch by 2-inch wood. The nail heads will protrude about half an inch, and you use them to make horizontal "scratches" on the first layer of stucco about an eighth of an inch deep.
After scratching the surface, allow the stucco to dry slowly for a day or two, occasionally misting it with water to keep it from drying too fast.
After the scratch coat has dried, apply the "brown" coat (or layer) about a half inch thick and "float" it to ensure it's smooth. Once again, allow this coat to dry slowly while misting it to keep it slightly moist while drying to prevent cracking.
Finally, it's time to apply the top or final coat. It's applied with a trowel in a layer about a quarter-inch thick and then finished with your desired pattern.
Create a smooth surface using a wood float across the surface, a swirled appearance by making short arcs with your trowel, or a stippled surface by dabbing the surface with a natural sponge.