Does your building have cracks like this?
It is common on a block building to see hairline cracks in mortar joints. In this article we will plan to repair them. The cracks typically run horizontally, and or stair step up. There are multiple potential causes of them, Starter course when the block was laid caused separation, Thin or no Stucco over the block. Deteriorated Paint. All these systems allow excess moisture and harsh UV rays to prematurely damage the mortar.
If the cracks are running straight vertical,
One of the most common solutions is to apply a brush grade elastometric patch.
This method can work to cover the crack only temporarily. Because of the movement in the crack the thin millage that was brush applied on top of the patch the crack typically reoccurs.
To properly repair the crack a deeper repair is needed. The first step is to cut open the crack to remove all loose surface material and to create a groove for the sealant to sit into. The use of a grinder with a V-shaped blade is needed to make a ¼” wide by ¼” deep groove directly on the crack.
Once the groove is established and flushed out with water it is ready to be treated. The key is to fill the crack with a flexible product to bridge the gap. BASF NP-150 is a common product to use. This will form a mini expansion joint. Once filled the groove can be topped with multiple products depending on the texture of the building. Stucco, base coat, and or more urethane sealant can be applied over the groove to mimic the current texture. The result is a crack that is now completely full of a sealant making it watertight and flexible with the correct millage to allow the joint to expand and contract without cracking.
The v-grooving repair process is necessary to protect a cracked building and to prevent further water penetrations.