​Concrete can crack for a myriad of reasons, often due to the complex interplay of several factors. Here are some common causes:

• Shrinkage: As concrete cures and dries, it shrinks. If the shrinkage is restrained, tensile stresses develop, which can lead to cracking. This is often referred to as drying shrinkage. 
• Drying Too Fast: If concrete dries too quickly, it can lead to increased shrinkage and cracking. Rapid drying can be caused by high temperatures, low humidity, wind, or inadequate curing practices. Proper curing is essential to control the rate of moisture loss and ensure the development of concrete strength.
• Lack of Expansion Joints: Expansion joints are crucial in allowing the concrete to expand and contract with temperature changes. Without them, the concrete is more likely to crack due to thermal stresses. If joints are not properly placed or designed, or if they are not filled correctly, cracks can form along these weak points.
• Lack of Quality Control: Improper mixing, placing, or curing of concrete can lead to defects and increased susceptibility to cracking. Too much water in the concrete mix can weaken the concrete, making it more susceptible to cracking. Certain chemical reactions within concrete, such as alkali-silica reaction (ASR), can cause expansion and cracking over time.
• Thermal Stress: Temperature changes cause concrete to expand and contract. Rapid temperature fluctuations can induce thermal stresses, leading to cracks.
• Freeze-Thaw Cycles: In colder climates, water can seep into concrete, freeze, and expand. This cycle of freezing and thawing can cause cracking.
• Load Stress: Concrete is strong in compression but weak in tension. Excessive loads, especially those causing bending or stretching, can lead to cracking.
• ​Subgrade Settlement: If the ground beneath the concrete settles unevenly, the unsupported concrete can crack due to the stress.
• Corrosion of Reinforcement (rebar): In reinforced concrete, if the steel reinforcement corrodes, it expands and causes the surrounding concrete to crack.

Proper design, material selection, and construction practices are key to minimizing the risk of cracking. Understanding the specific cause of cracking in any given situation often requires a detailed analysis of the construction process, materials used, and environmental conditions.

Manufactured homes provide a cost-effective and efficient housing solution for many. One common issue faced by owners of these homes is the appearance of cracks along the marriage line—the joint where different sections of the home are joined together. Hairline cracks are somewhat normal and nothing to be too concerned about. However, more significant cracks are generally caused by movement within the foundation system that need to be addressed. Understanding why these cracks form and how to repair them can help you maintain the structural integrity and aesthetic appeal of your home. In this article, we will explore the causes of these cracks and provide steps to fix them.

What is the Marriage Line?
The marriage line is the seam where two sections of a manufactured home are joined. This critical area is secured with bolts, screws, and other fasteners to help ensure structural stability. However, because it is a junction point, it is particularly vulnerable to stress and movement.

Why do Cracks Form?
Cracks along the marriage line in manufactured homes are primarily caused by foundation movement due to excess moisture in the soil, but can also be caused by thermal stresses and seismic movement. Moisture-related movement can occur due to several reasons:

• Drainage Issues: Water in the soil and pooling around the foundation can lead to soil erosion or swelling, both of which can destabilize the foundation. Some typical root causes of moisture issues are:
  • Lack of rain gutters
  • Downspouts that discharge next to the foundation
  • Homes installed on a slope with inadequate surface and sub-surface drainage (e.g. swales, French drains, etc.) around the home
  • Lack of ventilation in the crawlspace
• Soil Conditions: Expansive soils that swell with moisture and shrink when dry can cause significant foundation movement, leading to stress on the marriage line.
• Seasonal Changes: Temperature fluctuations (e.g. freeze and thaw) can cause the soil to expand and contract, leading to foundation shifts.
• Improper Foundation: An inadequately designed or installed foundation can shift, causing the sections of the home to move and develop cracks. An occasional problem are single-stack piers instead of double-stacked piers installation along the marriage line—check your home manufacturer’s installation and setup instructions.

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Fixing Cracks in the Marriage Line
Before addressing the cracks, inspect the foundation of your home or have it professionally inspected. Look for signs of movement such as: uneven floors; deteriorated wood pads and shims; tilted, sunken, or fallen-down piers; and gaps between piers and support beams. Also, look for signs of excess moisture such as: pools of water, evidence of past pooling, efflorescence (the white chalky residue left when water evaporates), wood rot, and soil erosion.

Step 1: Address the Root Cause(s) of the Problem

The first step is to address the root causes of the problem unique to your home, which are most often related to moisture. Common solutions include:

• Fix any plumbing leaks
• Address any grading issues (surface water drainage flowing towards foundation) which might include installing swale(s) to divert surface water away from the foundation
• Installing rain gutters
• Installing downspout extenders and splash blocks to divert water away from the foundation
• Install French drains around the foundation to remove water from the soil
• Improving ventilation under the home
• Installing a vapor barrier (link)

Geotechnical engineering is the study of the behavior of soils under the influence of loading forces and soil-water interactions. If you live in an area with expansive soils, please consult with a geotechnical engineer who may recommend soil stabilization techniques, such as:

• Adding lime to the soil reduce the plasticity and swell potential
• Adding cement or fly ash to improve the soil strength and reduce expansiveness
• There are other chemical additives that can be used

Step 2: Fix Foundation Issues While Re-Leveling the Home

This step is best done by professionals, but it is possible to do as a DIY project if you have the right tools (hydraulic jack, laser-level, bubble level, tape measure, etc.) and mindset. Common remedies include:

• Re-constructing tilted and fallen-down piers
• Installing additional (new) piers as needed
• Replacing single-stack piers with double-stack piers along the marriage line(s)
• Replacing (rotted) wood pads with prefabricated (plastic) or concrete pads
• Adding and removing shims to achieve level

​Optional advanced measures:

• Pouring concrete footers
• Replacing standard (dry-stack concrete block) piers with adjustable metal piers

Step 3: Repair the Cracks

Clean the cracked areas to remove any dust, debris, or loose material. This ensures that the caulk and joint compound adhere properly.

For small cracks, use a flexible, paintable caulk to fill the gaps. Load the caulk into a caulking gun and carefully apply it along the crack. Smooth it out with a putty knife and allow it to dry according to the manufacturer’s instructions.

For larger cracks:

1. Apply a layer of joint compound over the crack using a putty knife.
2. While the compound is still wet, place drywall tape over the area and press it into the compound.
3. Apply another layer of joint compound over the tape, smoothing it out to blend with the surrounding wall. Allow this to dry completely.
4. Once the joint compound is dry, sand the area smoothly with a sanding block or sandpaper. This helps to blend the repaired area with the rest of the wall.

Prime the repaired area to prepare it for painting. Once the primer is dry, paint the area to match the rest of your wall. This will help make the repair virtually invisible.

Preventing Future Cracks
While it's impossible to eliminate the risk of cracks entirely, you can take steps to minimize them by:

1. Maintaining proper drainage around the home to prevent water pooling and soil erosion.
2. Periodically inspecting your foundation yourself or have your home inspected by a professional to catch and address potential foundation issues early.
3. Depending upon need, it is recommended that you re-level your home every few years, with a suggested maximum of five year intervals.

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Conclusion
Cracks along the marriage line of a manufactured home can be a distressing issue, but they are often manageable with the right approach. By understanding that these cracks are typically caused by foundation movement, and by following the steps outlined above, you can repair and help prevent future cracks, ensuring your home remains safe and comfortable. Regular maintenance and attention to your home’s foundation are key to preventing these issues from recurring. With proper care, your manufactured home can continue to provide a secure and appealing living space for years to come.

Hidden beneath our feet, crawlspaces play a crucial role in the structural integrity and health of our homes. These dark and often damp places can harbor moisture-related problems leading to potential health hazards and structural damage. Thankfully, vapor barriers made from polyethylene plastic sheeting are a relatively inexpensive method to help control moisture. In this article, we explore the significance of vapor barriers in helping to prevent water from the ground causing high humidity within the crawlspace and the rest of the home.

Understanding the Role of Ground Vapor Barriers
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Excluding the obvious sources of water vapor into the crawlspace such as interior water leaks and water intrusion from the exterior, the single largest source of humidity within a crawlspace is from the ground itself through water evaporation. Water from the exterior of the house will infiltrate to the interior ground surface of the crawlspace through simple capillary action where it then evaporates.

A vapor barrier is a thin, impermeable material typically made from polyethylene or similar plastics. When installed on the ground in a crawlspace it acts as a protective shield, preventing water vapor from the damp soil below from rising and infiltrating the crawlspace and living spaces above. This simple yet effective technique offers a multitude of benefits, ensuring a healthier and more comfortable home environment.

The Perils of High Humidity

High interior humidity levels can lead to a host of problems, some of which may not be immediately apparent:

1. Mold and Mildew Growth: Excessive moisture encourages the growth of mold and mildew, leading to unsightly stains, foul odors, and potential health issues for occupants.
2. Dust Mites and Allergens: Humid environments provide an ideal breeding ground for dust mites and allergens that can trigger allergic reactions and respiratory problems in sensitive individuals.
3. Reduced Comfort: High humidity levels make indoor spaces feel sticky and uncomfortable.
4. Structural Damage: Prolonged exposure to moisture can cause corrosion of metal in electrical, plumbing, and structural components and can rot wooden beams, floor joists, and other structural elements, compromising the overall integrity of the home.

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Mobile and manufactured homes often have unique challenges compared to traditional houses, including a higher susceptibility to moisture-related issues. Due to their mobility and often temporary installations, they are more prone to uneven ground, which can lead to poor drainage and increased moisture within the crawlspace.​

Benefits of Vapor Barriers

The benefits of installing vapor barriers in crawlspaces are significant:

• Mold and Mildew Prevention: High humidity levels and excess moisture create an ideal environment for mold and mildew growth, ultimately leading to corrosion of metals, wood rot, and damage to structural elements. By helping to maintain a dry environment, vapor barriers extend the life of your home's foundation and other systems.
• Improved Energy Efficiency: By keeping the crawlspace dry, the installed insulation's effectiveness remains intact, reducing the strain on HVAC systems and resulting in lower energy bills.
• Pest Mitigation: Vapor barriers on the ground can help to discourage and thwart infestation from subterranean termites, burrowing animals, and other unwanted critters.
• Radon Mitigation: Radon is present in our area, but not prevalent; click here for more information. Ground vapor barriers are a common mitigation measure against radon, should that be present, promoting a cleaner and safer living environment.

 
In the quest to protect our homes from moisture-related issues, the vapor barrier has emerged as an invaluable ally. From controlling moisture and preventing mold growth to enhancing energy efficiency and structural integrity, vapor barriers play a vital role in safeguarding our living spaces. Embracing this essential technology allows us to ensure the long-term safety, health, and comfort of our homes.