What is Mobile Home Underbelly? – Care and Repair Tips.

Mobile home underbelly

Mobile home underbelly is an important part of the structure of a mobile home. It is sometimes referred to as the bottom board or belly board. This component helps to protect the underside of the home from moisture and other elements, while also providing insulation for the entire floor structure. The underbelly can be made from a variety of materials, such as aluminum, vinyl, fiberglass, or even wood. It is typically attached to the frame of the mobile home with screws or nails and sealed with caulking or foam sealant. Proper maintenance and repair of this component can help ensure that your mobile home remains dry and energy efficient for years to come.

What Is Mobile Home Underbelly?

Mobile Home Underbelly is the bottom of a mobile home. It consists of several components, such as the bottom board, floor joists, belly board and belly wrap. The bottom board is a flat piece of material that forms the base of the mobile home. The floor joists are wooden beams that run across the width of the mobile home and provide support to the floor. The belly board is a thin sheet of material that covers the underside of the floor joists and helps protect them from moisture. Finally, the belly wrap covers the floor insulation material that is installed between the joists under the mobile home to help keep it warm in cold weather. All these components work together to form a strong and durable underbelly for your mobile home.

What is Mobile Home Underbelly Made From?

Under belly is usually made from a breathable vinyl fabric or a thin reinforced paper. I have seen a number of different materials used including Tyvek wrap and thermo board sheathing.

The underbelly should be made from a material that allow the air to circulate in the subfloor space. Moisture and mold are the enemies of mobile homes in particular. The mobile home underbelly is a protective layer that is installed underneath the mobile home. It helps to protect the subfloor from moisture and other elements. The underbelly is usually made from Tyvek, which is a breathable material that allows air to flow through it while still providing protection from water and other elements. It also helps to insulate the home, making it more energy efficient. The underbelly also serves as an additional layer of protection for the subfloor, helping to prevent damage from moisture or other elements that may be present in the environment.

Why Do I Need Underbelly?

Mobile homes leave the factory with the bottom side of the home completely sealed.

The underbelly serves several purposes:

  • Protection during transport from the factory or dealer.
  • Holding up the floor insulation.
  • Covering electrical wires and plumbing pipes.
  • Prevents easy access for animals and pests.
  • Allows the sub floor to breath.

The bellyboard is an important part of any mobile home. It provides protection from the elements, helping to keep the floor and sides of the home warm in winter and cool in summer. Without underbelly, the floor of a mobile home would be exposed to extreme temperatures, leading to potential damage over time. Furthermore, without it moisture can build up underneath the home and cause mold or rot. Underbelly also helps protect against pests like rodents or insects that may try to enter through gaps in the floor or sides of the home.

Why Keep Your Bottom Board In Good Condition?

Keeping your bottom board in good condition is essential for the longevity of your mobile home. The bottom board, also known as a bellyboard, is the layer of insulation between the floor and subfloor. It helps to keep the temperature inside your home regulated and prevents moisture from seeping into the flooring. If it becomes damaged or worn out, it can cause serious issues with your home’s insulation and structural integrity.

  • Rats and cockroaches are always looking for easy access to your living area.
  • The underside of the home becomes very messy and difficult for repairmen to get safe clean access.
  • Although the underbelly is permeable it does prevent damp air from getting to the subfloor area.
  • The insulation can fall out of the floor causing increased heating and cooling costs.

Replacing a bottom board can be expensive and time-consuming, so it’s important to take steps to maintain its condition. Regularly inspect it for signs of wear and tear, such as cracks or holes, and repair any damage quickly before it gets worse. Additionally, make sure that any furniture or appliances are not placed directly on top of the bottom board as this could cause further damage over time. Taking care of your bottom board will ensure that you have a comfortable living space for years to come.

How Does a Belly Board Get Damaged?

A belly board can get damaged in a variety of ways. If the mobile home has been neglected, the underbelly may become exposed and vulnerable to damage from weather and other elements. Home repairs may be necessary if the underbelly of the mobile home has been damaged, as this can cause damage to the belly board itself. In some cases, animals may also cause damage to a belly board by chewing on it or scratching it with their claws. Finally, improper installation or use of materials that are not designed for outdoor use can also lead to damage.

Is Underbelly Repair a DIY Job?

Underbelly repair is a job that can be done by a DIY home owner, but it is not recommended. The underbelly of a home is the area underneath the house and includes the skirting. It is difficult to access this area and requires special tools and knowledge to properly repair any damage. If a home owner does decide to take on this job, they should make sure they understand what needs to be done and have all the necessary tools before starting. It may also be beneficial to consult with an experienced contractor or professional for advice on how best to complete the repairs.

A Damaged Underbelly Creates Several Issues

A damaged underbelly of a mobile home can create several issues. The mobile home underbelly is an important component of the mobile home as it provides insulation and helps with heating and cooling. If the underbelly is damaged, this can lead to problems with the floor and floor joists. Joists are used to support the floor, so if they are compromised due to damage from the underbelly, then this can cause serious structural issues. Additionally, without proper insulation from the underbelly, there may be issues with energy efficiency in the mobile home. Therefore, it is important to inspect and repair any damage to a mobile home belly in order to avoid further problems down the line.

How to Repair a Mobile Home Belly Board.

Repairing a mobile home belly board is an important part of maintaining the integrity of your mobile home. The belly board, also known as the underbelly, is located beneath the floor and serves to protect ductwork, insulation, and other components from damage. There are three main ways to repair the underbelly:

  • Taping up small holes with underbelly tape.
  • Using spay adhesive to cover holes with repair material.
  • Complete removal and re application of large sections between floor joists.

To repair a mobile home belly board, you will need to patch any holes or tears in the existing material. You will also need to replace any damaged joists or subfloor materials. Finally, make sure all HVAC ducts are properly connected and sealed before reinstalling the mobile home underbelly. With these steps completed, your mobile home will be safe and secure once again.

Mobile Home Underbelly Replacement Cost

Replacing the underbelly of a mobile home can be a costly endeavor. The cost will depend on the size of the mobile home and the type of insulation material used.

Repairing underbelly is the least favorite job with our work crew. Laying in the dirt with fiberglass insulation everywhere does not make for an enjoyable day.

  • The underbelly wrap is around $2 per square foot.
  • Roll of good duct tape. $9
  • Insulation is around $2 – $4 per square foot.
  • Half a days labor on a small job would be $200 or $50 per hour.
  • For example a 12′ x 4′ repair would be $96 + $96 + $100 (2 hours) = $292.80

 Most commonly, fiberglass insulation is used for this purpose as it is lightweight and easy to install.

Each piece of insulation material needs to be cut to fit the shape of the mobile home underbelly, making it more labor intensive than installing other types of insulation. Additionally, any old insulation must be removed before new fiberglass insulation can be installed. All in all, replacing a mobile home underbelly with fiberglass insulation can cost anywhere from $2-$4 per square foot depending on size and labor involved.

What’s a Vapor Barrier

A vapor barrier is a layer of material that helps to prevent moisture from entering a home. It is typically installed beneath the belly board of a mobile home, and can be an important tool for any homeowner looking to protect their property from water damage.

The vapor barrier acts as a protective layer between the ground and the mobile home, preventing moisture from seeping up into the structure. It also helps to keep out dust, dirt, and other debris that could otherwise make its way inside. A properly installed vapor barrier can provide peace of mind for homeowners by ensuring that their mobile home is protected from potential water damage. 


The mobile home underbelly is an important component in keeping a mobile home safe and energy efficient. Repairing or replacing a mobile home underbelly can be costly, but it is necessary to ensure the integrity and energy efficiency of the home. 

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