Many mobile homes built before 1976 only have between 1 and 4 inches of insulation. Many builders left voids and gaps throughout a mobile home and that’s assuming the builder cared to install insulation at all. Fortunately, it got a lot better after HUD code regulations began and there have been significant advances in mobile home insulation over the last 40 years.

Getting new insulation is one of the best ways to reduce your utility costs and increase your family’s comfort.

There’s a lot to sift through when it comes to mobile home insulation. Why do you need it? What is it? How do you measure it? We’ll take a look at all these questions, and take some of the intimidation factors out of mobile home insulation so you chose the best insulation for your home regardless of its age or model.

Advantages of Installing new Insulation in a Mobile Home

According to the Department of Energy, mobile homes built prior to the 1976 Department of Housing and Urban Development (HUD) codes have a special need for added insulation. But even for those with newer homes, there are some clear benefits:

  • Reduced Utility Costs. According to the Insulation Institute, homeowners stand to save 15% on heating and cooling by adding insulation to the home. This number actually increases in older homes, since in many cases they’re poorly insulated to begin with.
  • Increased comfort. It’s not all about the savings. When it comes to enjoying the comfort of your home, there’s definitely something to be said for increased comfort. Having a warmer, better-insulated home makes it easier to get out of bed in the wintertime, and easier to stay cool in the summer.
Vapor barrier and insulation in new manufactured home floor
Vapor barrier and insulation in a new manufactured home floor.

Measuring Insulation R-Value

In general, heat flows from warm areas to cool areas. So, during the colder months the warmed air inside your home will be trying to flow out, while in the summer, the hot air outside will be trying to flow indoors. Let’s break down how this law of nature interacts with materials in your home:

  • Conduction refers to how heated air travels through materials, and insulation works to alter this “conductive” property of material so that less hot air will flow out in the winter (or in, in the summer) through your walls.
  • Convection refers to how heat circulates through the air (or liquids). Stopping this flow of air via convection within walls or openings can also moderate energy usage.

The ability of a material to resist heat flow is measured by its R-value. The higher the R-value, the more effective it will be at insulating your home.

Different insulation materials will have different R-values. Also, the R-Value is dependent on your climate zone and the part of your mobile home you’re insulating and what zone you are in.

Most Cost-Effective Energy Improvements for Mobile Homes

The NRLE (National Renewable Energy Laboratory), has partnered with the US Department of Energy to conduct experiments on the effectiveness of different weatherization techniques on mobile homes in colder climates.

The NRLE experiments found that the most cost-effective improvements were

  • air sealing and duct repair
  • furnace tune-ups
  •  blown roof insulation
  • interior storm windows
  •  blown floor insulation

Notice how it says blown insulation? They tested between blown and fiberglass batt insulation and found that the batts were often damaged during installation and therefore lost effectiveness.

Heat Loss Reduction by improvement on mobile home
Heat loss reduction testing results.

Most Popular Types of Insulation

Let’s break this down a little further by looking at some of the most popular types of insulation.

Blanket: Batts and Rolls. This is the most common type of insulation out there. As the name suggests, it’s found in the shape of batts (rectangular pieces) and rolls (cylindrical pieces). It’s made of flexible fibers and can be cut to a width where appropriate. This makes it a good choice for between stud and joint spacing.

Foam Board. Where batts and rolls are soft and flexible, foam boards are quite rigid and provide excellent thermal resistance.

Loose fill/blown-in. As opposed to the previous two types of insulation, loose fill/blown is composed of small particles that can be used to fit into virtually any space with amazing flexibility. That’s why this type is great for areas that have obstructions or oddly-shaped spaces and older mobile homes.

Sprayed Foam/Injected. Foam materials can be used as insulation as well, and are unique from the other forms in that they are sprayed as a liquid that hardens, filling even the smallest of spaces to create an air barrier. Injection foam is generally used in enclosed spaces (like walls), while injection foam is used in open areas (like the attic).

installing insulation into a mobile home during remodel - dcdiva blogspot

Popular Materials used for Mobile Home Insulation

Each of the types of insulation we just discussed can be made out of various materials.

Fiberglass is the Most Popular Insulation

Fiberglass insulation is a great choice for insulating homes and is the most commonly used insulation in manufactured homes. It doesn’t burn, rot, or but it does require heavy protection when installing it.

Fiberglass’s name comes from its structure: which is actually made from molten glass that is formed into very small fibers. Bulky materials like foam achieve their insulation effects by limiting conductive heat flow. You’ll find fiberglass in two types of insulation:

  • High-density fiberglass batts/rolls
  • Blown Fiberglass
  • Batt Fiberglass
  • Batt insulation is usually used between studs, trusses, and floor joists in mobile homes. UNfaced batts are best to re-insulate mobile homes. Fiberglass insulation with the facing is harder to install and can trap moisture even though its meant to do the exact opposite.
  • Blown Fiberglass

Advantages: Fiberglass is made of soft fibers, which means it’s very flexible. It is also a very effective insulator and cost-effective which is why it’s been a favorite insulator for homes for decades. You don’t need any specialized tools except breathing masks and skin protection.

Disadvantages: Unless you use plastic-sealed batts, fiberglass can trap moisture but it doesn’t deteriorate much when it gets wet, it just loses its effectivenss. As far as health goes, the small glass fibers of fiberglass can be dangerous to breathe in, damaging the lungs and provoking allergies when inhaled. Its R-value also decreases over time as it settles. And unfortunately, critters love it!

The NERL found that one of the biggest issues for batt insulation is the reduced efficiency due to improper installation.

mobile home wall insulation 3d image created by Mobile Home Living


Foam is a Versatile Insulation

Aside from fiberglass, one of the other most common materials is foam. Made from plastics as opposed to glass fibers, foam comes in diverse shapes. It can take the form of a rigid foam board, or be sprayed as a liquid then harden as insulation. It can be made from various plastics:Molded Expanded Polystyrene (MEPS)

Expanded Polystyrene (EPS)

Extruded Polystyrene (XPS)

Polyurethane Sprayed

Foamed-in-place Polyurethane Insulation

Advantages: Foam boards offer a high insulating value relative to their thickness (as opposed to fiberglass, which is more voluminous). And spray-in foam is an excellent solution for awkwardly-shaped or difficult-to-reach areas. It also reduces the chances for mold, moisture, dust, and pollen.

Disadvantages: Generally, it’s more expensive than fiberglass structures. Also, it takes longer to install and can’t always be installed as part of a DIY project since you may need specialized equipment.

Cellulose: Recycled Paper

Cellulose fibers can take the place of fiberglass fibers in insulation materials. Instead of glass, cellulose is made out of recycled paper that is concentrated down and then formed into fibers. Some other natural materials you might see for insulation include:

  • Cotton
  • Wool
  • Straw
  • Hemp

Advantages: Cellulose is an environmentally-friendly option since it’s produced from recycled materials. Unlike fiberglass, it doesn’t bear the risk of causing lung damage.

Disadvantages: It has to be replaced every five years in many cases, especially if it absorbs water. Unlike fiberglass, it often requires a professional to install it.

What Kind of Insulation and Installation is Best for Each Section of a Mobile Home?

A lot goes into choosing the type of insulation you’ll need for your mobile home. First, you need to decide which kind of material is right for your home. Second, you’ll need to chose the kind of installation that is best for each area of your home.

Once those two decisions are made you’ll need to hire an insulation installer or prepare yourself for an intensive DIY project. Depending on your material,  you may need a contractor with specialized equipment or rent/buy your own.

We’ll take a quick look at how this could look in different sections of your mobile home.

blowing insulation into a mobile home underbelly - floor
Blowing insulation into a mobile home.


Mobile Home Floors and Belly

When we talk about a mobile home “belly,” we’re basically talking about the area under the floor system of the mobile home. You have a couple of options for adding insulation to this area but the preferred is to blow it.

blowing insualtion into mobile home underbelly

If you have complete access to the underside of your mobile home because your belly wrap is missing or damaged and needs to be replaced anyway you may consider fiberglass batts/rolls or foam board. Batts and rolled insulation can easily fit between mobile home floor joists but both require a ton of cuts. These cuts and the complex installation can damage the insulation which will reduce its efficiency.

Foam board would require as much cutting as the rolls and batts but it may be easier to handle because it’s rigid. You can install foam insulation board yourself. We already published an article about installing foam board insulation to your mobile home belly.

If you don’t have complete access to the belly of your home you’ll likely want to use a blower to spray insulation.

The floor cavities in mobile homes usually have a ‘blanket’ attached to the bottom of the 2″x6″ floor joists that we call a belly wrap. If your mobile home has transverse floor joists (see the image below, traverse joists follow the width of the home) the position of the ducting may create a dropped belly that causes problems if you are trying to blow insulation into the space. Therefore, it needs to have the belly attached to the joists properly to create smaller channels that will require less insulation.

blowing insulation through the rim joist of a mobile home lengthwise and crosswise

Average insulation densities for loose fill insulation installed in mobile home bellies will be 1.25 to 1.75 pounds of blown fiberglass per cubic foot.- Green Energy Plus

blowing insulation into a mobile home underbelly 2
Blowing insulation into a mobile home underbelly.
Rim Joist and Wing

The rim joist and wing can also be used to get insulation into the belly of your mobile home. As with the other methods, blowing insulation into a rim joist requires drilling holes. However, if the rim joists is a foundational component it cannot be modified so that knocks it out for many homeowners.

drilling a hole into a mobile rim joist home rim joist to blow insulation into it
Drilling into mobile home rim joist to blow insulation.

Mobile Home Walls

Mobile homes made pre-1976 have very thin sidewalls with poor insulation. Again, as in most cases, batt/roll can be cut and sized to fit inside the walls of your mobile home in the ‘stuff it‘ or stuffing technique. This is a good way to go if you are remodeling the home and will be removing walls and ceilings.

The foam spray/injection method can be used as well to fill all small cavities and prevent conduction and convection. The only issue with the spray/injection method is that you may need special equipment or a contractor.

removing siding on a mobile home to blow new insulation
Installing insulation behind the metal siding on a mobile home.

Older mobile homes with vertical metal siding will do well with the sidewall stuffing technique. The metal siding is installed with screws attached to a horizontal belt rail. To get to the spaces between each stud you’ll need to remove the bottom row of screws to give the blower pipe access.

blowing insulation insto the ceiling of a mobile home
Going through the ceiling to blow insulation into the mobile home roof.

If you are remodeling your home you will have a much easier time installing insulation into your home. In this mobile home remodel, the owners replaced the insulation and the old paneling and ceiling.

new insulation in mobile home ceiling during remodel
New insulation added while remodeling the interior of a mobile home.

Ceilings and Roofs

If you don’t have easy access to the ceiling or roof of your home, and most don’t unless they are in the middle of a remodel, you will need to blow insulation into the space.

There are a few different methods of blowing insulation into the ceiling and roof of a mobile home. You can do it from the exterior using a drill and plug process or go from the interior through the ceiling. Both methods require drilling holes and inserting a rigid pipe that shoots the insulation into place.

where to blow insulation in a mobile home with a bowstring roof

Though we love the idea of DIY projects, for ceilings and roofs, you probably need to hire a contractor. This is because ceilings are usually insulated with blown insulation, which necessitates an insulation blower. To do this, an insulation blower is used to fill each truss bay with insulation. The roof space can be accessed from either inside the mobile home (called interior blows) or by “lifting the lid” or drilling holes and blowing insulation into the space.

blowing insulation in a flat roofed mobile home

For bowstring trusses, you likely have only 1-2 inches of insulation around the edge but 10″ in the center of the home. Over time that insulation can become wet or damaged in a number of ways. Lightweight sloped-roof trusses can have around 3 inches of insulation at the edge and possibly up to 2 feet in the middle. In both cases, getting the perimeter insulated is difficult, even for the most experienced.

The installer will need to blow the insulation in a uniform coverage and with a density between 1.25 and 1.75 pounds per cubic foot.

DIY Spray Foam

Spray foam insulation has come a long way since it first hit the market. Previously, you needed specialized blowers and hoses to blow the insulation into a cavity so it was only available to homeowners that could afford to hire a company with the equipment.  Now, there are DIY kits available for homeowners but there seems to be a love/hate opinion about these kits.

Ideally, a professional should always be hired when dealing with insulation because there are so many variables that need to be considered. Electrical and plumbing systems complicate insulation installation. An understanding of air sealing and evaporation is also important before spraying the first inch of foam. Still, spraying foam insulation yourself is a smart mobile home improvement project that can save a ton of money on heating and cooling and make your home more comfortable.

The Rewards of Greater Insulation

There’s no need to suffer the consequences of poor insulation. By insulating your mobile home properly, you’ll reap the rewards of a warmer and more comfortable home. Not to mention, you’ll probably save quite a bit on energy costs — and get that much closer to turning your house into a home.

There’s no doubt about it, adding new insulation is the absolute best improvement you can do to your mobile or manufactured home, especially an if your the home is older.

It’s our goal to provide the most helpful information so please don’t hesitate to check out more tips on our website. If you’re interested in learning more, please feel free to contact us with any questions — or tips of your own. There aren’t enough resources for mobile home owners and we aim to change that.

As always, thank you for reading Mobile Home Living!

12 thoughts on “Learn how to Install New Mobile Home Insulation”

  1. Hi! We own a pre-1976 mobile home in Michigan. I’m in the process of removing the entire underbelly all the way to the floorboards. The old insulation and boards are pretty nasty. The home is seasonal, summers only. Do I need to insulate at all? I’m not interested in holding heat or cool air inside the home. I’d like to just clean out all the old material and leave as is. When finished, I will replace the skirting to keep critters out. Thanks for your thoughts!

    1. Hi Matt,

      Yeah, you really should add insulation. It’s cheap and would be a fairly quick install since you’ve gutted the underbelly already. Just staple it between the joists.
      If you don’t your plumbing will freeze and you’ll get condensation on your walls and ceilings that will lead to mold and mildew due to temp fluctuations. Go ahead and get the ducting and venting sealed up as best as you can before you add the insulation.

      Best of luck!

  2. I don’t know if I’m commenting in the right space but I have a question that to be honest am embarrassed to ask. I removed my batten on my wall in the hallway because I hate them. I used the tape and joint compound to seal the spaces. I used a thin coat the first time and sanded it down & was going to do another coat. My husband insisted I wasn’t doing it right. I panicked and totally screwed it up. The tape I used you could see it even with the sanding. The compound was really uneven and the more I sanded the worse it got. Finally I just painted over it and hung pictures over it. I don’t want to leave it that way. I know it’s there and it bothers me immensely. Help! What can I do to fix this?

    1. Hi Kathryn,

      Please don’t be embarrassed! We have ALL done things that didn’t work out during our remodels! You tried something and it didn’t work but at least you tried! Every home has at least 3 ‘oopsies’ or it can’t be considered a true home…lol

      You probably only needed a little caulk and a little bit of mud to fill in the seams that the battens were covering. By using the tape you may have added too much ‘height’ and then when you started sanding you may have sanded the vinyl or paper off which made the gypsum show? The reason they use battens is that the VOG/POG walls aren’t tapered at the edges like sheetrock so that makes taping and mudding difficult (as you’ve found out). At this point, I would probably get the wall as smooth as possible and then find a thick paintable wallpaper. Or, maybe you could use more mud and a template to add a dimensional design to cover that seam only (a tree or Greek column would work).

      Best of luck!

  3. Hi Crystal,
    Great info here, especially for those of us who have never had to think about adding insulation. You didn’t mention insulation behind skirting, which is what I need here in upstate New York. I have the original, cheap vinyl stuff right now, but it needs to be replaced. Do I have many options?
    Thank you for any advice!

    1. Hi Robynne,

      I have read a few opinions and test results for insulated skirting and it seems every professional has a different opinion. One says you should always use insulated skirting, another has fancy charts and graphs to show that you don’t. It’s really kind of ridiculous how different opinions are about insulated skirting of all things! I’m gonna side with the numbers – the NERL did tests and it showed insulated skirting was the 5th best energy saving improvement or upgrade.

      The expert that says there are better places thinks you should spend the money to insulate the floor and ducting and lay a ground barrier instead.

      Also, think about skirting ventilation. In the winter you have vents open allowing the cold air under the home anyway (you want air circulation to dry up the snow and ground moisture) so it’s counterproductive to insulate the space you want air to flow through.

      Personally, I would buy the thicker, higher quality virgin vinyl skirting (not made from recycled material) instead of insulated skirting and back it with the cheaper foam board or fan-fold insulation behind it. Next, I would add an insulated box or ‘skirt’ around your plumbing pipes running between the ground and the home and then seal up all your ducts and either blow insulation or use foam board or fiberglass roll/batt between the joists. A new belly wrap and ground barrier are good investments (but you can always just repair that belly wrap).

      Hope that helps!

  4. Crystal,
    This is one the most informative articles I have ever read concerning home improvement. And your timing is spot on – after just spending 3 days/nights here in Florida with the evening temperature of 37 degrees the heat pump was turned on to get to a comfortable temperature. My wife suggested that I research adding insulation under the house , which I will do soon – but your information has saved me time and has educated me to what to expect once I get started. Since the interior is all done – I have plenty of “spare” time.

    Very well written and filled with facts – thanks.

    1. Thank you, Chuck! That means a lot, especially from you because you know your stuff!

      I have left out a couple things I need to add. Namely, using a flexible board to help add rolled or batt insulation between the floor joists (I can’t find photos of it and I can’t describe it properly). I also forgot to mention that drilling holes over the studs on the sidewalls will help you fill in two spaces with only one hole. Fewer holes are always good!

      I’m trying to focus on more helpful articles (though I really need to stop using the word guide, you’d think I’d figure out how to use a thesaurus by now!) Thanks again!

  5. Thank you for this informative article about insulating mobile/manufactured homes. I would like to ask about the R values for the ceiling, walls and floors. If you have that information, I would appreciate it. Thank you for your site and all the helpful information you provide along with inspiring remodels! ~Carol

      1. TruMH by Clayton only have R-14 celiings and R-11 walls. You have to live in Climate zones 2 and 3 to even get the upgraded R-14 walls. To overcome this lack of insulation they have monster 40,000 BTU furnaces. If I were to buy one of these (they are VERY affordable, obviously for a reason) the first thing I’d do is build false walls inside the trailer with offset studs and more insulation, and that would have the added benefit of getting rid of the god awful vinyl on gypsum wallboard. Then clad the inside walls with shiplap or rough cut lumber, a much nicer more modern look. You’d save a bunch on heating in the winter, especially if you plastic the windows and could tolerate a little colder temps. For every 1.8 degrees F ( 1 degree C ) lower you can stand, you burn 10% less fuel. So if you can keep your trailer at 55 F instead of 70 F, you burn 75% less propane.

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