There’s a lot of pressure associated with the search for the perfect tiny house insulation. Choose something too heavy and it’s impossible to tow; choose something too thin and you’re left shivering during winter.
With so many options to choose from, it can feel like a never-ending rabbit hole of R-values, costs, and installation instructions.
So what’s the best insulation for a tiny house? Choosing one depends on a variety of factors including R-value, installation technique, where you live, and your interior wall dimensions. The best insulation for you may not be the best insulation for someone else.
It all depends on your tiny home and your tiny lifestyle. In this article, we include everything you need to know about insulating your tiny house.
The Goal of Tiny House Insulation
Every tiny house needs reliable insulation. It’s not just for folks living in colder climates -- it’s also for homeowners living in hot, arid environments. Insulation works by preventing heat flow from one area to another and preserving temperatures within a space.
In the winter, you want to prevent the heat in your home from escaping or “bleeding through” the walls and onto the cold outdoors. In the summer, you want to keep the heat out as much as possible in order to save the cool air from your AC.
By paying attention to your insulation, you’re creating an energy and cost-efficient tiny house that can keep you cooler or warmer, without using too much energy. A good insulation system also keeps condensation at bay, preventing mold and water damage from compromising the integrity of your tiny house.
What to Insulate In a Tiny Home
Just like in a traditional home, your tiny house walls are going to need protection from extreme temperatures. This means insulating within cavities including hard-to-reach areas where there are wires and plumbing.
To take precautions against extreme temperatures, some builders even line the outside of their tiny house framing with thin foam board insulation in order to offset thermal bridging. Keep in mind that another protective layer outside of your tiny house could mean going beyond the limits of a road-friendly width.
Majority of tiny homes have lofts as their sleeping quarters. This makes roof insulation an integral part of the build. When insulating a tiny house roof, you want to make sure there is a gap between the roof sheathing and insulation material to allow ventilation.
By doing this, you can keep the air dry in between that space and prevent condensation and mold damage to your roof.
3. Floor and Trailer
There are two ways to go about insulating the floor or trailer. In most DIY cases, builders choose to lay down the subfloor first, then insert the insulation into the cavities. However, this technique bridges a connection between the wood layer and the metal trailer bed. Keep in mind that materials like metal and steel are powerful conductors of temperature.
Even if you’re doing a tiny house subfloor insulation with R30 material, its practical r-value will drop because the frame is still in contact with the metal. This can drop as much as 35% depending on your location and materials used.
The more meticulous way of doing it is by insulating the trailer bed before setting up the subfloor framing on top of it. With this method, you can also cover the metal around the base of the trailer. The insulation acts as a barrier between the subfloor and trailer, preventing heat loss and securing your tiny home in the most efficient way possible.
Tip: If you don’t want to go through the trouble of insulating around the base of the trailer, you can just raise your floor framing so the wood that comes on top of it doesn’t get in contact with the metal below.
4. Wheel Well
The wheel well is the little house where your wheels go for extra protection on the road. It’s built from the same material as the rest of your trailer. Unfortunately it does take up space and requires you to build around it.
There are different ways to insulate and make the wheel well a seamless part of your home’s design, but there are two techniques we prefer. The first one involves making a box that covers your wheel well. This method is simpler because you install the insulation directly on the box and just seal up the well with it.
The other method involves insulating the wheel well directly. In both methods, malleable material such as foam and spray works best. Although more time-consuming, the biggest benefit of doing it the second way is the assurance that every nook and crevice is insulated. You can also use thinner plywood to seal up the wheel well, which could give you more floor space.
How Much Does it Cost to Insulate a Tiny House?
This depends on your tiny house size and your chosen material. For a standard 350 square feet tiny house using top fiberglass material, full DIY installation could cost only $224. If you’re planning to use a more expensive material like hemp, it can cost close to $500 for insulating the same space.
Upfront savings don’t always translate to long-term gain. A durable material like hemp will last for years and won’t require additional work because of its fire resistant and moisture wicking capabilities. While cheap, you might end up hiring a professional to do your fiberglass installation, which could mean an additional $150 to $200 for labor.
Things to Consider: Shopping Tips
Choosing the best tiny house insulation isn’t as simple as getting the material with the highest R-value. To really get the best out of your insulation budget, you need to consider all the different factors that come into play, from how the insulation is laid out to how your material reacts with the environment.
During your research you probably came across the term R-value a lot. The R-value is really just a way of measuring the material’s thermal resistance, or its efficiency in preventing heat flow. When we talk about heat flow, we’re not just referring to high temperatures. Heat travels from a warmer space to a cooler space until both temperatures are roughly the same.
Heat flow can describe:
- Hot temperature from the inside seeping through the windows because of the cool air inside the house
- Warm air from the heater seeping out of the house because of the cool air outside the house
A material’s R-value determines how efficient it is in preventing heat flow. The higher the material’s R-value, the better it is as an insulation.
A basic insulating material such as fiberglass can have an R-value of 2.5 per inch, while a thinner material like polyurethane foam can have an R-value of 3.4 per inch.This just means that polyurethane is more effective in preventing heat flow than fiberglass.
Density VS R-value?
Does adding more layers of an insulation increase its overall R-value? Yes, it does. But the rate of how the R-value changes is dependent on the material. Some increase linearly while others increase exponentially. Knowing this could help you cut down costs for the overall material.
The Changing Nature of R-Value
R-value might be the definitive way of understanding a material’s insulation capabilities, but it definitely shouldn’t be the only number you’re looking at. Installation, exposure to moisture, and temperature are the top factors that can drastically affect a material’s R-value.
Polyisocyanurate or just simply polyiso is another common insulation material, popular because of its high R-value. If you look at the numbers alone, its R6/ inch rating is pretty impressive and energy-efficient.
The downside is that this material performs worse in colder temperatures. A study found that polyiso can lose as much as 25% of its R-value when the temperature drops. Practically speaking, polyiso could be a great tiny house insulation for folks living in Florida and Arizona, but could be a waste for those living in North Dakota and Minnesota.
Is R-value a practical unit of measurement?
Yes and no. As a laboratory measurement, the R-value helps you quantify and compare insulation materials in your head, provided that all the necessary steps are taken to properly insulate your tiny house.
In a practical setting, a material with a supposed R-value of 5 could actually come close to 3 or 4 per inch because of improper installation, unsealed air pockets, gaps and seals between the frames and studs, and thermal bridging.
At the end of the day, it’s important to understand how your material performs in your temperature. Don’t just look at the R-value - search practical world applications and see how they perform in real temperatures.
Where Do You Live?
Where you live determines how much insulation you need in your home and what kind of tiny house insulation is best for you. The Department of Energy’s list of recommended R-value for given states is helpful in deciding how much insulation to install in your tiny home.
Zone 1 includes Hawaii, Guam, Puerto Rico, and the Virgin Islands
Zone 7 includes all of Alaska except for the following boroughs classified under Zone 8: Bethel, Delingham, Fairbanks North Star, Nome, North Slope, Northwest Artic, Southeast Fairbanks, Wade hampton, Yukon-Koyukuk
|Zone||Attic||Cathedral Ceiling||Cavity||Insulation Sheathing||Floor|
|1||R30 to 49||R22 to 38||R13 to 15||None||R13|
|2||R30 to 60||R22 to 38||R13 to 15||None||R13 to 25|
|3||R30 to 60||R22 to 38||R13 to 15||R2.5 to 5||R25|
|4||R38 to 60||R30 to 38||R13 to 21||R2.5 to 6||R25 to 30|
|5||R38 to 60||R30 to 60||R13 to 21||R2.5 to 6||R25 to 30|
|6||R49 to 60||R30 to 60||R13 to 21||R5 to R6||R25 to 30|
|7||R49 to 60||R30 to 60||R13 to 21||R5 to R6||R25 to 30|
|8||R49 to 60||R30 to 60||R13 to 21||R5 to R6||R25 to 30|
You will notice that the recommended R-value for the attic in states with the hottest climates (zone 1 and 2) are similar to the ones recommended for colder states (zone 7-8).
This is because the difference in temperature between the outside of the house and the inside are roughly the same in both cold and hot climates. The same insulation will be needed to prevent heat transference from one place to another.
How Thick Are Your Walls?
A tiny house doesn’t have a lot of room to spare. How thick your walls are will decide how much insulating capability your house has. Wall thickness is also determined by the materials you use, meaning a thicker wall with more insulation will also be heavier and less road-friendly than a thinner wall.
The standard tiny house wall uses 2x4 inch framing, which typically gives way for 3.5 inch insulation material that offers roughly R13 to R15 insulation. A thicker build using 2 x 6 in wood will allow you to use thicker insulation of up to R21.
For tiny homes with space to spare, there is always the option of adding an inch of insulation board on the exterior, just underneath the exterior siding. The benefit to this is added protection without having to take so much space inside the tiny house. The downside is that the exterior width might extend beyond the limit, making it difficult to transport your tiny home.
Buying the materials is just part one of the tiny house insulation. The last and crucial part involves the actual installation of the material on your wall. When done right, you can be sure that your R-values are up to par, provided you’ve taken into account thermal bridging and sealing air leaks.
Can you install insulation in your tiny house without a professional? You definitely can. As long as you employ careful techniques, you should be able to properly insulate your home.
For fibrous insulation materials like fiberglass, rock wool, wool, hemp, and cellulose, it’s important to ensure that the material isn’t compressed.
During the installation, make sure the material doesn’t lose its shape and remains “fluffy”. Pressing into the material removes the air pockets that trap the heat, which will in effect lower its R-value.
For foam insulation materials, your priority is to measure the cavities and fit out the material as closely as possible. Having a canister spray foam seal insulator is a great option for sealing off the small patches of uninsulated space and other hard-to-reach corners.
Types of Insulation
Shopping for your tiny house insulation can be pretty overwhelming. We like to organize insulation material under two major categories: fiber insulation and foam insulation. These categories describe what the material is made of and how they are installed.
There are two types of foam insulation: rigid and spray. We’re going to focus on fiber and rigid foam insulation since those are the ones that are best for a tiny house given that they are cheaper, easier, and cleaner to install.
Fiber insulation are those made out of some type of fiber. This includes wool, cotton, rock wool, cellulose (recycled material insulation), and fiberglass. This type of insulation can come in batts (rolls) or blocks with an average R-value of 3.5 to 4 per inch.
Fiber insulation is malleable and expandable. The good thing about this is you can take pieces of the insulation material to seal off small corners near the stud and other nooks and crannies.
Not all fiber insulations are created equally. Fiberglass, the cheapest of the lot, is notoriously hard to install. For starters, this material is difficult to cut and shape. When installing, it’s very possible for you to push too much and remove the necessary air bubbles that preserve the fiberglass’ integrity. After cutting, fiberglass doesn’t taper off, making it difficult to fit it to make a clean, precise cut.
If you’re looking for more precise materials that hold their shape, check out semi-rigid fiber insulation like rock wool. This type of insulation comes in blocks that you can easily cut off with a bread knife. It holds its form, making it easier to work with.
Cost depends on the kind of fiber insulation you use. Fiber insulation can go for $0.50 up to $1.25 per square foot. Most are available in standard sizes of 3.5 inches for 2 x 4 frame and 5.5 inches for 2 x 6 frames.
Most fiber insulation aren’t built with a vapor barrier. A vapor barrier is a thin material placed between the insulation and the wood. This material traps the vapors from condensation and prevents any damage on the surface of the sheathing.
A vapor barrier typically costs $0.50 to 0.75 per square foot, which means a reliable vapor barrier can cost an extra $175 to $263 for a 350 square feet tiny house.
Foam insulation, specifically rigid foam insulation, is a type of insulation that uses synthetic foam to prevent heat flow. They are made out of lightweight foam that won’t shift or move during travel. There are three types of solid foam insulation, each with different R-values: polyisocyanurate (R6.5), extruded polystyrene or XPS (R5), and expanded polystyrene or EPS (R3.8)
Like fiber insulation, rigid foam boards can be cut up to fit into the installation area. Because of its rigid nature, it might be challenging to fit a foam insulation in awkward spaces. DIYers find themselves having to cut multiple small pieces in order to fill out certain spaces.
Foam boards typically come with manufacturer-approved tape that is used to attach the insulation. Spray foam insulation in cans are usually added to seal off any excess space.
Higher R-values means slightly more premium prices. Rigid insulation can go for $0.70 to $1.73 depending on the material you’re using.
Standard foam insulation are sold in 1 to 2 inch thickness. Most builders stack up the foam boards in order to reach 3+ inch thickness. You can also have these manufactured in your desired thickness, but the cost will be higher than those readily available in stores.
Rigid foam insulation already comes with vapor barriers so you don’t have to spend extra to seal up your home.
Is Spray Foam Insulation Good for a Tiny House?
Spray foam insulation is another popular type of insulation that has high R-values and great sealing capacity. However, it’s not commonly found in tiny homes. Most tiny homes use the two types of insulation mentioned above because of three reasons:
Spray foam is difficult to install and requires a professional.
Spray foam has to be mixed, installed, and cured properly by a professional for it to work. It has the tendency to expand and spill over structures, which can be frustrating for first-time builders. When mixed incorrectly, spray foam has been known to shrink away from the studs, which is a huge potential for heat loss.
For its R-value, there are cheaper alternatives.
Spray foams have to be installed by a professional, which is another thing to add to your tiny house insulation budget. There are more eco-friendly options you can use that don’t require additional costs.
Spray foam poses a health risk to homeowners.
Spray foam insulation uses chemicals that are harmful to humans when ingested. Its primary component, isocyanate, can induce respiratory problems and even lead to the development of asthma.
This doesn’t mean that spray foam can’t be used on tiny homes. In extremely cold temperatures, a mix of spray foam + a rigid foam board might be used to effectively insulate the home. When done right, spray foam can make your tiny house comfortable even in the harshest of climates. Just make sure you’re working with a skilled and experienced professional to really get your money’s worth.
Top Insulation Options for a Tiny House
Cost / sq. ft: $1.37 to $2.40
Can be DIY: Yes
Insulation from hemp fiber is one of the best all-natural insulations you can use. Hemp fiber is a great fiber insulation alternative to fiberglass and other common insulation materials. Hemp is naturally pest-resistant. Even as a biodegradable material, hemp can last years.
Even when wet, hemp doesn’t lose its insulation capabilities. Hemp insulation has zero VOC emissions, guaranteed breathable, and is all-around a great insulating material. Hemp also requires no vapor barriers since it can regulate moisture effectively.
The only downside is that hemp is hard to find in North America. It is more accessible in Europe and some parts of Canada. Because of the limited production, hemp products are typically found in semi-rigid forms; some companies are thinking of producing it in batts form for easier use.
A variety of the product called Hempcrete can also be used as an insulative material. This is treated with lime acid to create the structure.
R-Value: R3 - R3.3, depending on the manufacturer
Cost / sq. ft: $0.62 to $1.50
Can be DIY: Yes but wear gloves and mask
Also called mineral wool, this insulation material is made out of inorganic rocks and slag (waste from steelmaking and other industrial processes). These materials are combined and spun into a fiber to create the material. This process involves using high temperatures to fuse the material together.
As such, rockwool is extremely resistant to high temperatures and is considered as one of the best fire retardant insulation materials available. It can tolerate temperatures of up to 1000°C or 1832°F. With this much heat tolerance, rockwool burns slowly and can prevent the spread of fire from one area to another, giving residents a chance to evacuate or extinguish the fire.
Rockwool doesn’t just prevent heat flow; its dense fibers also make it a great acoustic barrier.
Cotton / Denim
Cost / sq. ft: $0.76 to $1.41
Can be DIY: Yes but incredibly difficult
Cotton insulation is also referred to as “blue jean” insulation with recycled denim as its primary material. Although great for the environment, there are some trade-offs when it comes to denim insulation.
It absorbs moisture more than any other insulation material. Denim insulation is difficult to install because most fits are not accurate to fit in 16 inch cavities of the standard 2 x 4 studs. Builders tend to complain about the insulation crumpling at the side, which significantly reduces its effectiveness.
Good installation techniques and a heavy-duty vapor barrier are necessary if you’re keen on using denim insulation on your tiny house. On the other hand, denim is one of the heaviest insulation materials, and may not be ideal for tiny house on wheels (THOW).
R-Value: R3.5 to R3.8
Cost / sq. ft: $0.67
Can be DIY: When bought as batts
90% of the wool sheared from sheep in the U.S. are being thrown away according to a West Coast Green conference. Wool comes in the form of batts or 100% loose wool. The batts variety can be applied the same way you install a fiberglass, while the other requires a professional to “blow in” the insulation.
Like its processed counterpart, wool has amazing fire retardation qualities. It will only ignite in temperatures of 570 to 600° C or 1058 to 1112° F. This material doesn’t have to be treated with chemicals in order to become fire resistant. As a natural material, sheep wool is also good at wicking away moisture. Like rockwool, it also has good soundproofing capabilities.
However, wool is not inherently pest-resistant and is quite prone to insect infestation, particularly moth. You’ll have to treat your insulation separately or buy from a manufacturer that has treated their product with pest repellents in order to get the most out of your natural insulation.
R-Value: R2.9 to R3.5
Cost / sq. ft: $0.64 to $1.19
Can be DIY: Yes but incredibly tricky
Fiberglass is made by fusing recycled glass and sand at incredibly high temperatures. Despite this, fiberglass doesn’t have fire resistant qualities. In fact, fiberglass can be highly flammable and additional treatments are required to promote fire safety when using this as an insulation material. The variety with vapor barrier paper backing is especially flammable.
Its main selling factors are affordability and weight. As a common insulation material, it’s incredibly easy to get your hands on affordable fiberglass batts. However, fiberglass batts don’t have the rigid form like rockwool or hemp, and is known to get dislodged with impact. If you’re building a THOW, you should consider something more road-ready.
Dense Pack Cellulose
R-Value: R3.6 to R3.8
Cost / sq. ft: $0.80 to $2.05
Can be DIY: Yes but equipment rental is necessary
Cellulose is made up of recycled materials mainly newspapers and woodchips. Cellulose can be packed densely, increasing its R-value and improving its fire-resistant quality. On the other hand, you might have to hire a professional to install this. Most dense pack cellulose is installed through a blow-in method. Attempting to do this on your own is possible but is not advisable to first-timers.
Structural Insulated Panel (SIP)
R-Value: On average, R3.8 per square foot
Cost / sq. ft: Varies
Can be DIY: No
Structural insulated panels or SIPs are gaining traction in the tiny house community for their versatility. Think of SIPs are prefabricated insulation and wall in one. Insulative materials are either made from closed-cell polyurethane foam spray (CCPFS), XPS, or EPS.
These insulated panels are great for creating an airtight seal on your tiny home, without compromising the weight or the width of the material. SIPs can only be manufactured and installed by a professional and cost more than traditional insulation options.
It’s a viable option for tiny house insulation on wheels since it’s lightweight. Despite using CCPFS, it’s not as harmful as installing it in a closed attic. In an open warehouse, builders can control the chemical and let it cure before installing it in your home.
R-Value: R6 to R7
Cost / sq. ft: $0.67
Can be DIY: Yes but protective gear is required
Polyisocyanurate (simply polyiso) is a highly dense insulation material with an impressive R-value. Its relative affordability and efficiency makes it one of the top choices for tiny house insulation.
However, polyiso is limited to temperate and hot climates. Studies show that exposure to cold temperatures actually decrease its R-value, making it more susceptible to heat flow in lower temperatures.
Extruded Polystyrene (XPS)
Cost / sq. ft: $0.75 to $1.45
Can be DIY: Yes but protective gear is required
XPS foam board insulation starts as polystyrene crystals then melted and formed into foam. Manufacturers used to claim their R-values were closer to R5 but tests showed that the blowing agents used in the process wears overtime, reducing its overall insulation potential.
XPS is lightweight and known to be moisture resistant. On the downside, XPS foam board is not fire retardant and can give off toxic fumes when ignited. Additional reinforcements on the sheathing will be required in order to properly protect your tiny house in case of a fire.
Expanded Polystyrene (EPS)
R-Value: R3.8 to R4
Cost / sq. ft: $0.75 to $1.45
Can be DIY: Yes but protective gear is required
EPS foam board is created by expanding the same polystyrene crystals used to create XPS. Compared to XPS, EPS is more breathable, allowing air and moisture to move through the material instead of being trapped inside it. This foam board a better vapor barrier than XPS but we still recommend installing a vapor barrier layer to really offset condensation damage.
EPS’s biggest selling factor is its ability to maintain its quality for years to come. Its insulative capabilities temporarily drop by as much as 15% when wet, but goes back to normal once the surface is dry.
Perfect Insulation for Your Tiny Home
If you’re a frequent traveler who doesn’t mind spending a premium price on quality insulation, along with strict weight requirements, then SIPs might be a good option for you.
If you’re living in a stationary tiny house in forgiving climates and want the cheapest option available, then fiberglass is definitely the way to go.
If you’re looking for something you can do on your own, then rockwool insulation might be the best option for you.
The search for the perfect insulation for your tiny house relies on your lifestyle. As we discussed, there’s no straightforward way to answer this.
Where you’re living, how you’re heating or cooling your tiny house, and what you're looking for in a material will determine viable options for home insulation.
Hey, there! We're Ivan and Manuela from Croatia, and we're crazy about tiny houses. We don't own one (yet).
This website is a result of our passion to share all the knowledge, photos, tips and tricks that we were able to learn while studying everything possible about the tiny house movement.