Can You Use Spray Foam Insulation In a Mobile Home? (Solved)


Yes, spray foam can be used as insulation in mobile homes, among the general weather requirements stipulated by HUD (U.S. Department of Housing and Urban Development), it states that in the case of spray polyurethane foam (SPF) insulation in manufactured homes, the installed thickness of the covered areas and the R-value of the installed thickness must be stated in the certification.

Among the positive properties of spray foam is that it is resistant to pressure, aging, and rotting. The material does not absorb moisture from the air, as its closed cell structure prevents water absorption. In addition, it is resistant to mold and rot, as well as odorless and therefore safe for use with foodstuffs.

What is the insulation R-value of a material?

The R-value is a basic concept used in construction in relation to insulating materials, but it is very likely that you have not heard about it, it is important that you are aware of this concept if you are trying to understand what is your best option to insulate your mobile home.

The measure of the thermal resistance of insulating material is known as the R-value, in short, measures the effectiveness of the insulating material in reliably resisting the heat that can be transferred by conduction or contact through the material.

The R-value is the heat transfer coefficient. It indicates the resistance to heat flow, i.e. how much a material resists cooling, in other words: how well an object insulates as a function of its thickness. The higher the R-value, the lower the heat loss.

An insulating material with a high R-value will not only keep your home protected from the cold during the winter but will also keep it cool during the summer.

What is foam insulation?

Insulation with foam is a relatively modern method that has been gaining popularity due to its effectiveness, Spray foam insulation is the application of polyol resin and isocyanate, two chemical products that when combined, react with each other forming a dense and expandable material.

The adaptation that is achieved with the expansion together with the high insulation value that is achieved with this material, makes it one of the most efficient and adaptable materials as insulation for mobile homes.

In fact, in any type of house with a stud structure that requires insulation, spray foam insulation can be very well adapted, because it fills the cavities that are formed between the studs, and then everything is sealed with the coatings.

How does spray foam insulation work?

Spray foam insulation is a type of insulation that is sprayed in place with a spray gun. Spray foam insulation can be blown into walls, concrete slabs, attics, or under floors to insulate and reduce air leakage.

Spray foam can fill even the smallest cavities to create an effective air barrier. After spraying, the foam typically expands 30 to 60 times its liquid volume. It offers excellent resistance to air entry (unlike batts and blankets, which can leave drifts and air pockets and is superior to some types of loose-fill).

On the other hand, the cost of spray foam insulation can be higher compared to traditional insulation, and most foams, with the exception of cementitious foams, emit toxic fumes when burned.

There are two types of spray foam insulation:

Closed-cell foam: Closed-cell foams are better insulators. Their high-density cells are closed and filled with a gas, with the help of which the foam fills the surrounding spaces. Closed-cell foam is very strong and structurally reinforces the insulated surface.

Open-cell foam: The cells of open-cell foam are not as dense and are filled with air, which gives the insulation a spongy texture. Open-cell foam is porous, so water vapor and liquid water can penetrate the insulation. On the other hand, open-cell foams allow the wood to breathe and are about twice as effective as sound insulation.

Cautions when using spray foam insulation in a mobile home

Important precautions should be taken when deciding to apply foam insulation, here is a list of some recommendations and compilations of opinions by contractors and users of houses that have used foam insulation, both for good and bad experiences:

1-Not a DIY project

Applying foam insulation to a mobile home may seem like a very easy, quick, and simple job, this is true, but only for trained installers, this type of work is not for the inexperienced, or major disasters could occur.

It requires a skilled person, the most important thing is the preparation of the foam, which is necessary to know the correct measure of mixture between the two components that make it up, things could go very wrong if the components are not mixed properly.

The application of the material, also requires technique and knowledge, especially, do not over-apply the material at the same point, and many other details to take into account that only a trained installer can handle efficiently when applying the foam.

This consideration also includes not hiring “the friend who does the job on the cheap”, insulating the mobile home will be an investment anyway, so that the work is guaranteed, try to get a contractor to do the job.

2-Beware of piping and electrical wiring

When spray foam insulation is applied to a mobile home, special care must be taken with water pipes and electrical installations, this is common sense for any good installer, the disadvantage of completely covering the pipes with spray foam is that in case of a possible leak it is difficult to detect and all insulation material in the area must be removed.

There have been cases of small leaks in water pipes, which when covered by the foam, develop leaks that are difficult to detect and can affect other areas. However, it is recommended that in exposed areas of the house, hot water pipes should be properly insulated.

3-Do not expose yourself immediately to freshly installed spray foam

Generally, when working in interior spaces with materials that collect some type of chemical mixture, or that release gases in its application, it is recommended not to be exposed directly for at least 12 hours.

That is why, when it is decided to paint the interior of a house or apartment, it is done in hours where there is no person inside, and let the interior of the house degas, with the application of spray foam in the mobile home is the same.

Although modern spray foam does not contain large proportions of chemicals harmful to humans, it is advisable to allow the house to degas during and after application.

4-A large layer of spray foam is not necessary.

Many people think that the more spray foam applied, the more effective it will be as insulation, on the contrary, a thin layer of spray foam is enough, the experienced contractor knows very well the effective amount, it is not necessary to demand, for example, 4 inches thick in the application of spray foam.

Is spray foam insulation non-combustible?

According to DIN 4102-1 (fire test to building material) Spray foam is classified as B1 and B2 material, (B1 = low flammability, B2 = normal flammability), the insulation does not drip while burning. Without a supporting fire, the material is self-extinguishing. Post-combustion processes, which are often the cause of smoldering fires and fire spread, do not occur with polyurethane-based insulation materials.

Is spray foam toxic?

Currently, the technology used to insulate with spray foam contains formaldehyde-free formulations that do not emit volatile organic compounds and also uses technology without ozone-depleting blowing agents, so spray foam can be considered an environmentally friendly material.

Less energy is used in the production of plastic products, including polyurethane foam, than in the production of alternative products. In addition, it should be noted that the spray foam insulation system increases the energy efficiency of the house and reduces losses.

Can spray foam insulation be removed?

Yes, the spray foam can be removed once it is dry, the consistency of the spray foam although solid, is elastic and can be easily cut with a knife, saw or any cutting tool that facilitates the work, sometimes when required to install extra pipes in the house, it is possible to remove the spray foam simply by cutting it.

In much tighter spaces or at the edges of doors and windows, tools such as a chisel, hammer, and spatulas can be used to remove the spray foam.

Where should you not use spray foam insulation in a mobile home?

As a general rule, spray foam should not be used in areas in close proximity to electrical boxes, and special care should be taken to cover water or electrical pipes, which should always be accessible, It should be noted, however, that HUD recommends that all hot water piping outside the conditioned space should be insulated.

Due to the heat hazard of the ceiling lightboxes, spray foam should not be applied in this area, as the narrow space and heat build-up from the light can cause the material to catch fire.

Spray foam should not be applied in areas of the attic where there is not at least visual access to verify the work being done, and spray foam should not be applied in areas of the attic that receive ventilation from the side soffits.

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  1. Good morning, Elvis. I found your commentary very informative. I have a CAVCO (2019) mobile home (~1920 sq. ft.) that I designed to be handicapped accessible before it was constructed. I did not have to presence of mind to note if the roof (attic) was insulated before it (double-wide) joined. It’s my belief that the contracted company who installed the home may not have insured the insulation was in place. This Summer the ceiling (used a heat gun) reaches 90+ degrees (F). The HVAC is a down-flow with seven (7) floor registers & two (2) toe. The HVAC (single stage blower) is in the hallway, and when it turns on, it sounds like a tank. The mobile home manufacturer cut transfer vents in several rooms to vent/duct those rooms, but a lot of dead zones. Question: Will closed-foam cell insulation be a viable option (professionally applied) coupled with “Whirlybird” braced vents to mitigate the attic heat?

    Thanking you in advance.

    1. Hi, closed foam cell insulation can work very well for the attic, as can open foam cell insulation, the main difference is that open foam cell is more cost-effective, some installers can do a combination of both as well.

      Whirlybird” braced vents are an excellent idea to ventilate the attic and at the same time extract any harmful buildup, however, make sure that the foam insulation to be applied in the attic has low VOC.

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