Mobile home insulation

Insulation is an important topic if you plan on living in a mobile home. Because of the thin walls in mobile homes and RV trailers, heat gets transferred more easily, and that means it can be unbearably hot or cold at different times of the year, depending on where you live.

The area below the mobile home has various names: mobile home belly board, bottom board, underbelly and crawlspace. Regardless of what you call it this are, it needs to be properly insulated. Insulation in this area is referred to as: mobile home belly wrap, bottom wrap, belly and belly barrier. 

Insulation efficiency is measured with an R-value. The R-value represents how well a material insulates heat. That means a material with a higher R-value is more efficient at insulating. Let's look at two commercial products as an example: Prodex total 5M plus has an R-value of 17, while Prodex total 10M has an R-value of 22, so Prodex total 10M is a more efficient insulating material.

Before any insulation work, check your local codes to see what the regulations are for insulation. Inspections are a necessary evil in the construction world, they can sometimes be a pain, but they ensure safety. Having this in mind, your location will greatly impact what kind of insulation option is best for you. After all, houses in Florida and Canada, for example, have very different weather conditions to deal with.

Insulation for under mobile home

The most important place for insulation is the roof of your mobile home. The fact that hot air rises is the reason why insulation with the highest R-value is needed on the roof. Poor roof insulation is directly tied with higher energy costs.

Wall insulation is right after roof insulation in terms of importance for mobile homes. This is because, like the roof, walls make up most of the area of the home. All mobile homes have wall insulation, but it’s typically thin material with a low R-value.

All mobile homes have some sort of underbelly. At first, you may think crawlspaces don’t need much if any insulation, but it actually is an area where insulation is necessary because of plumbing. Some types of insulation are better than others, especially for mobile home underbellies. Fiberglass and cellulose are quick and cheap options but are highly susceptible to absorbing moisture, resulting in mold, mildew and rot.

Spray foam insulation may be a better option than fiberglass or cellulose for underbellies. There are two types of spray foam: closed cell and open cell. Both last 3-4 times longer than fiberglass and have air sealing properties and also act as acoustic wall insulation. Closed cell spray foam is generally regarded as the better spray foam option, because open cell spray foam can soak up moisture like fiberglass and cellulose.

Are mobile homes difficult to insulate?

Mobile homes are different than regular houses. As describe in their name, they are mobile. They are also light-weight. As a result, they have thinner walls than regular houses. Having thinner walls means heat can penetrate more easily. This presents a challenge in figuring out how to install proper insulation.

Most mobile homes are under-insulated. They usually don't have any insulation in the walls or floor. They have a reputation for being drafty and having unstable interior temperatures, leaving anybody who lives in one uncomfortable. There are many options for mobile home insulation, some of which are pretty easy to do by yourself cheaply, while others require specialized equipment, knowledge and are more pricey, but are better in the long run.

Which types of insulation will work best for mobile homes and RVs?

There are many materials that do a good job of insulating all types of mobile homes and RVs, most of which are also good as van insulation. Blown insulation is a popular insulation for mobile homes, but it is expensive because you have to hire it out. Blowing insulation into the belly and ceiling of a mobile home construction requires specialized equipment and knowledge of a mobile homes construction. Fortunately there exist government programs that may help mobile home owners to add insulation via energy grants and low-interest loans. You may qualify for a program or financing for mobile home insulation depending on your location, especially if it was built before 1976.

Other solutions for mobile home that aren’t as expensive as blown insulation are:

  • Spray foam
  • Rigid foam
  • Fiberglass
  • Rock wool

Spray foam is recommended for areas that are already enclosed such as walls or ceiling of a mobile home. Spray foam is a bit on the pricey side compared to other options, but is considered as one of the best options. Some of the best options for closed cell foam we stock are: Prodex total 5M and Prodex total 10M. These reflective insulation rolls surround the closed cell polyethylene foam with reinforced reflective foil.  If you have a smaller budget and want to save a bit, you can even make your own diy spray foam insulation.

Rigid foam insulation comes in three common types: expanded polystyrene, extruded polystyrene and polyisocyanurate. All of them are petroleum-based products. Rigid foam is suitable for walls, ceilings, foundations, for new or existing constructions. 

There are many advantages of rigid foam insulation, such as:

  • relatively easy to cut with a hand saw, or table saw
  • lightweight and easy to carry
  • doesn’t promote mold growth
  • water resistant
  • long-lasting – won’t decay
  • insecticide is used on most foam making

Expanded polystyrene or molded expanded polystyrene (EPS or MEPS) is the most common type of rigid foam insulation, and by that virtue, the most affordable. It’s made from the same closed cell foam beds that shipping peanuts and coffee cups are made from. The R-value of EPS depends on its density and ranges from 3.6 to 4.2 per inch.

Extruded polystyrene (XPS), also known as blue board or pink board comes in lots of thicknesses and edge profiles. This type of foam is the most used in the residential construction industry. XPS has an R-value of 4.5 to 5 per inch.

Polyisocyanurate (Polyiso or ISO) and Polyurethane is used in all kinds of commercial building applications and as of recently with residential building projects. These kinds of rigid foam insulation have the highest R-value per inch, but they are also the most expensive of the three rigid foam materials. Polyurethane foam has foil that covers the sides, creating a vapor barrier which is useful for floor and roof insulation. Polyiso has an R-value of 7 to 8 per inch.

The biggest disadvantage of rigid foam insulation is probably fire. Foam insulation doesn’t catch fire easily, but when it does, it emits dense smoke and toxic gasses. However, some manufacturers make spray foam with fire retardant, so it shouldn't be an issue.

Materials Used in Mobile Home Insulation

Other than foam insulation, blanket (batt) insulation is a pretty common option for mobile homes. It consists of several layers of fiberglass, rock wool or other similar materials stacked together to form a blanket which can be installed on ceilings, floors and walls. It is often protected by thick layers of paper or cardboard, which helps from moisture. Blanket insulation is one of the most affordable and easy to install options, so you can ease your budget with this option.

Fiberglass is a type of blanket insulation that is made from very fine strands of glass formed in rolls and loose fill bats that are installed between beams, studs and joists. Since it is made from glass, fiberglass blankets are affordable and non-flammable. A big downside of fiberglass is that it is fairly dangerous to handle. It also loses R-value if introduced to moisture. Fiberglass has an R-value of 2.9 or 3.8, depending on the density.

Rock wool is another type of blanket insulation made from rigid mineral wool that is non-combustible, water-repellent, fire-resistant and sound absorbent. Rock wool has an R-value of 2.5 to 3.85 per inch.

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