Stucco Installation and Conditions Before starting

We check to make sure Weather Conditions before starting the stucco application, it is crucial to check the weather forecast. The ideal conditions for applying stucco are overcast days with low wind and temperatures between 50 to 60ºF (10–16ºC). If temperatures are expected to drop below 40ºF (4ºC) or rise above 90ºF (32ºC) within the week, it is advisable to delay the project. If we're working on a sunny day, store stucco and sand under a tarp to prevent them from getting too warm.

Stucco can be applied over various rigid materials attached to support studs, such as plywood, oriented strand board (OSB), cement board, or exterior-grade gypsum sheathing. Ensure compliance with local building codes when installing these materials. For an open frame application, nails should be driven halfway into the studs at intervals of 5-6 inches (13-15 cm), and string line wire should be strung horizontally along these protruding nails.

Normally we cover the sheathing with building paper and then add a dimple screen or rain screen for drainage. Most building codes require at least two layers of “Grade D” building paper or an equivalent water-resistant barrier. Overlap the paper by at least 4 inches (10 cm) and fasten it securely with roofing nails, starting from the bottom and working upwards.

We select appropriate metal lath for stucco application and install it properly by nailing or stapling it to the studs at intervals of no less than 7 inches (18 cm). Overlap lath edges by at least ½ inch (1.25 cm) along long sides and 1 inch (2.5 cm) at ends. Use only galvanized roofing nails or staples designed for stucco applications.

To minimize cracking in the stucco finish, divide large wall areas into rectangular panels using control joints spaced no more than 18 feet (5.5 m) apart. Control joints should also be installed where two dissimilar walls meet.

Prepare the scratch coat by mixing one part cement material with 2¼ to 4 parts plaster sand. If using Type I Portland cement instead of plastic cement, add hydrated lime accordingly. Mix with just enough potable water so that it can be troweled without sagging.

Using a square trowel held at a 45-degree angle, apply the scratch coat firmly onto the lath until it reaches a thickness of about ? inch (9.5 mm). This first coat should adequately cover the wire grid beneath. Once applied, lightly score horizontal lines into the scratch coat using a notched trowel; this will enhance bonding with subsequent layers.

Allow the scratch coat to cure for approximately 48 hours while ensuring that it remains moist during this period to prevent rapid drying out. After curing, additional coats can be applied following similar procedures-mixing appropriate materials and ensuring proper curing times between each layer until achieving desired thickness and finish.