kxa...if you only want to repair the crack, then route it with a small grinder, then fill with a sealant compatible with whatever coating you are using on the stucco.
An 1/8" wide crack in stucco is unusual. You need to determine the cause of the crack. Is it shrinkage? Is it improper lath placement? It is improper sheathing placement?
Stucco is often considered to be waterproof. It is not, particularly when you have cracks such as this. Check to see that control joints are placed such that no more than 144 square feet are in any area. Also, windows and doors are often used by architects as "control" joints in stucco. The window joint should be continued to the bottom termination, whether at the ground level or at a floor line joint.
Assuming it is applied over wood framing/sheathing, conventional stucco is applied in 3 coats...the first coat is called a scratch coat, the second is a brown coat, and the third is the finish coat. The thickness is measured excluding the finish texture.
Generally, the stucco is applied onto an expanded metal lath covered substrate. My preference is to apply roofing felt over a "housewrap" covered substrate, then apply the lath separately. Many prefer to use paper backed lath, but it is much more difficult to achieve proper flashing tie-in with paper backed lath.
The three layers of stucco have specific functions. The first coat, the scratch coat, is to provide the initial bond and foundation for the succeeding coats. It is also the one that should be used for primary crack mitigation, in that it is applied and then horizontally scored (scratched) so that very tight shrinkage cracks can form in the first layer. The second layer is the "brown" coat. It is called a brown coat because it should have a higher sand percentage than the scratch coat, so that less shrinkage occurs (and correspondingly less cracking) as compared to the scratch coat. The finish coat may be the same mixture as the scratch coat to provide a dense, durable surface resistant to moisture intrusion. In conventional stucco the layer thicknesses are required to be 3/8", 3/8", and 1/8" successively, to achieve a total thickness of 7/8".
One coat proprietary stucco systems do not directly meet code requirements. They slip in through the back door by the use of "Evaluation Reports" by code authorized testing agencies. In order for them to comply with the code, they must be approved by the building official, and they must follow, to the letter, the requirements of the Evaluation Report. They almost never follow those requirements!!
Control joints are placed to break up the areas into sections no larger than 144 sq. ft. I often see control joints installed improperly in that they are fastened to the substrated on both sides, thus negating the movement they are supposed to accommodate.
Hope this helps. I could write for the next hour on stucco and its construction problems!! I see them a lot.
kslee1000...sorry I didn't fully answer your question. Most stucco is applied using a trowel. It can, and often is, applied by spraying. There are several finish techniques that use a brush to apply spatterings of stucco then use some other finish technique such as a trowel rub to achieve a knock-down finish or a rilled surface.
Joints around penetrations are formed and sealed. Control joints are generally not sealed. They are constructed using pre-formed control joints.
Is that a cementitious material... looks more like EIFS? Some of these products and the foam backing have very high shrinkage until they have cured properly.
