How to Save Your Marriage Line

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.