Updated on September 27, 2020
The exterior walls of a house can have different types of finishes such as wood, brick, vinyl, stone, or stucco. Stucco is another common finishing material that has been used for centuries from the era of Greek architectural design up to the modern days. In the U.S. it is also known as the “exterior cement plaster”. It provides a durable finish and an aesthetic beautiful wall surface.
Stucco is basically a porous, thin layer of concrete which over time can develop small cracks if water penetrates through the insides. This problem compounds in rainy areas with high winds. The wind brings pressure on the exterior surface which pushes the moisture or water through the surfaces of stucco. Thus, a reliable stucco finish should incorporate a way for water to escape from behind its surface. Take note that if the stucco has already an existing leak, applying paint over won’t cure the damage.
Stuccos are popular covering for walls and ceilings. It is usually applied to masonry walls, brick, concrete or concrete block, but it can also be applied to wood-framed walls. If done properly, a stucco wall on wood sheathing is also attractive and long-lasting.
Wood frame wall or light-frame construction is a group of dimensional lumber or engineered wood lumber that is equally spaced and attached together using nails to create a wall. Stucco can also be installed in this type of framing.
How to Install Stucco Over a Wood-Framed Wall
Prepare a wood-sheathed wall for stucco. Install a moisture membrane and attach it to the wood sheathing using a construction paper. If there is any window or door, place a metal flashing surrounding it. Nail it to the sheathing using a hammer and galvanized nails. Shield the wall with metal lath, securely nailed at stud locations using galvanized nails. Put weep screed below the lath at the bottom part of the wall to capture any moisture that gets behind the lath and let it drain.
Mix the stucco scratch coat. You may check the package for instructions on how to properly do it. Using a rectangular mason’s trowel, spread the stucco over the lath with ⅜ to ½ inch thickness. After it starts to set with the notched edge of the trowel, horizontally scratch it to form depressions that will hold the second coat. Let it sit for 48 to 72 hours while keeping the moisture level up. You can use a garden hose to occasionally mist it with water.
Mix more stucco with a little more sand in it to form the brown coat. Spread it over the scratch coat using a trowel with ¼ to ⅜ inch thickness. Screed it with a long straight board move along its surface to smoothen it. Let it dry for a while misting it with water periodically.
Apply the finishing coat of stucco using a mason’s trowel with 1/16 to ⅛ inch thick. Slightly dampen the brown coat with water first. You can finish this coat with any preferred texture. Let it dry while hydrating like the previous coats.