5 Common Causes of Stucco Cracks (When to Worry)

Stucco cracks are not only an embarrassing eyesore, but they just might be a huge red flag pointing to compromised structural integrity and possible foundation failure.

The truth is, stucco cracks are always a symptom of a deeper issue, not the problem itself. Of course, you want to know what stucco cracks are a legitimate cause for concern and which are mere cosmetic gaffs.

Dalinghaus Foundation Repair has been repairing foundations since 2011, more than 2,000 projects so far. It’s safe to say, we know our way around stucco cracks and their common causes. We wrote this article to help you properly diagnose your stucco cracks and assess their level of severity.

This article covers 5 different kinds of stucco cracks, their likely causes, and how to address them if they originated from serious foundation issues. By the end of this article, you will be able to identify stucco cracks and be able to determine the best course of repair.

5 Common Stucco Cracks

Stucco Hairline Cracks

Stucco hairline cracks are narrow fractures that generally run 1/16th of an inch in diameter or less. They are referred to as hairline cracks due to their thin, wispy, hairlike appearance. Stucco hairline cracks can be caused by a variety of factors: improper mud mixture, new home settlement (from drying timber/framing), seismic movement, and foundation settlement.

The majority of stucco hairline cracks are caused by benign factors that don’t pose a threat to your foundation or the structural integrity of your home. The wider and deeper the crack, the bigger the issue. In addition, if hairline cracks are allowed to deteriorate and widen, moisture may soak into and through your stucco, instigating more damage.

*Note, sometimes stucco hairline cracks manifest as stairstep cracks. That is, the crack pattern follows the cinderblock structure. This crack pattern is often a sign of foundation settlement.

In short, hairline stucco cracks are common and can be easily repatched. Most are not a serious indicator of foundation damage or structural disrepair. However, hairline cracks caused by foundation settlement will likely reappear after the repair and worsen.

Stucco Foam Trim Cracks

The foam trim utilized in stucco installation can also crack, indicating that fiberglass mesh tape was not correctly implemented (if used at all). This results in two pieces of stucco not fitting tougher at the seam. Stucco foam trim cracks are susceptible to contraction and expansion depending on the weather, this cycle instigating further deterioration.

These cracks, if left untreated, can lead to severe damage due to exposure to the elements. Be sure to reach out to a professional handyman or construction company to appropriately address the problem.

Stucco Hairline Cracks

Stucco hairline cracks are narrow fractures that generally run 1/16th of an inch in diameter or less. They are referred to as hairline cracks due to their thin, wispy, hairlike appearance. Stucco hairline cracks can be caused by a variety of factors: improper mud mixture, new home settlement (from drying timber/framing), seismic movement, and foundation settlement.

The majority of stucco hairline cracks are caused by benign factors that don’t pose a threat to your foundation or the structural integrity of your home. The wider and deeper the crack, the bigger the issue. In addition, if hairline cracks are allowed to deteriorate and widen, moisture may soak into and through your stucco, instigating more damage.

Stucco Cross-Patterned Cracks

Stucco cross-patterned cracks look like a grid with overlapping vertical and horizontal lines. This indicates the lath was improperly installed. The lath is a framework (usually a mesh, metal wire, or waterproof paper pattern) that provides the framework for the mud stucco to adhere to.

If the lath was not properly stapled or nailed to the structure, it can break away and compromise the structural integrity of the affected area, creating stucco stress fractures.

To repair this stucco crack will require a complete lath removal and replacement. This is not a DIY project and a serious undertaking. You should hire a construction company or professional handyman.

Stucco Spider Cracks

Stucco spider cracks, you guessed it, resemble a spiderweb pattern. Stucco spiderweb cracks are caused by insufficient use of mud in the stucco mix (often created by overuse of water). These cracks can also form if the mud mixture dried too quickly (if the day was too hot to dry the mud evenly/properly).

These cracks do not represent a serious threat to your home’s foundation or the structural integrity of your home.

Learn more about, Vertical Wall Cracks: Causes And Repair Options, and read about the causes of vertical wall cracks.

Stucco Diagonal Line Cracks

Stucco diagonal line cracks typically originate around door/window frames and AC units. These cracks are almost always indicative of severe foundation damage resulting from foundation settlement or foundation heave.

Stucco Cracks Caused by Foundation Settlement

Stucco cracks caused by a settling foundation are serious because they signal possible foundation damage. The vast majority of the stucco cracks we here at Dalinghaus run into are the direct result of foundation settlement.

As mentioned previously, foundation settlement translates into stucco diagonal cracks and hairline cracks. The diagonal cracks, specifically, are a key sign and symptom for diagnosing foundation settlement. These are cracks to worry about.

Foundation settlement is when a foundation sinks or settles into incompetent, non-load-bearing soil. These weak soils are referred to as expansive soils, such as loam or clay soils (which are both highly impacted by the volume of water saturation). More water equals soil expansion, and less moisture equates to soil shrinkage.

As you can imagine, the constant expansion and shrinkage of the soil beneath your foundation can exert a tremendous amount of stress upon your home. Energy is always transferred. The pressure from the soil transfers through your foundation, into the framing of your home, outward into the stucco, and inward into the drywall.

Odds are if your foundation is suffering from settlement, in addition to stucco cracks, you would notice:

• Cracks in your drywall
• Sloped floors
• Doors that are difficult to open/close (due to the warped frame)

Foundation settlement requires foundation repair to appropriately address the stucco cracks. The issue with caulking over the cracks before the foundation repair is completed is that the cracks will return with gusto. The root of the issue has not yet been addressed.

The best way to combat foundation settlement is foundation underpinning. Generally, underpinning is undertaken with push pier and helical pier systems.

These pipes are driven into the earth until they reach competent, load-bearing soil or bedrock and act as stilts to support your home.

Once your home is properly supported, push pier and helical pier systems allow for practical maximum recovery (the possibility of regaining inches lost by settlement). After your home has been brought up to maximum practical recovery and/or stabilized, then the stucco cracks can be patched.

To learn more about how the underpinning process works and understand how it secures your foundation against expansive soil, read our article about, Underpinning A House.

Be Proud of Your Stucco

In this article, you learned about 5 common forms of stucco cracks and their various levels of severity. You also learned about how foundation settlement (a serious foundation failure condition) can result in diagonal stucco line cracks and stucco hairline cracks. The most serious stucco cracks are caused by foundation settlement.

We know you’re tired of being embarrassed by your stucco home. Reclaim your pride and patch-and-paint your stucco or have a professional come out and address the issue. We’d love to evaluate your home and help diagnose your stucco cracks.

Dalinghaus Foundation Repair has completed more than 2,000 foundation projects since 2011. We’re here to educate and help provide peace of mind.

If you’re seriously concerned about foundation settlement, before you consider booking a free evaluation, be sure to read our article 5 Signs and Symptoms of Foundation Issues. This article will walk you through the most common signs and symptoms step-by-step to provide a clear picture of what foundation settlement looks like on the inside and outside of your home.

Also you can check, What’s Involved In A Home Foundation Inspection?

Schedule a Free Evaluation

Foundation movement is easier to judge in person than from a photo. Schedule a free evaluation and a Dalinghaus specialist will walk the property with you and explain what the evidence shows.