Tiny House Insulation Basics
When designing and building your tiny house, choosing the correct insulation is a very important step. The type of insulation you will need depends on several factors. These include budget, availability, difficulty of installation and most importantly the effectiveness of insulation.
Heat naturally rises, so you have to plan your tiny house insulation with that in mind. That means the highest-value insulation should be on the roof, then on the walls, followed by the floor.
The main two factors in choosing insulation are the application (use) and the insulation effectiveness. The R-value rating is a measurement of insulation effectiveness, it measures how well a material resists conductive flow of heat. You don’t need to know the details of the R-value measurement, but it can come in handy when comparing different insulation. For example, Prodex total 10M has an R-value of 22 compared to Prodex total 5M which has an R-value of 17. In basic terms, that means Prodex total 10M is more effective vs 5M. The R-value of reflective
insulation is the measurement of a system. The R-value rating of mass insulation is given by the inch. For example, an inch of fiberglass has an R-value of 3.14 which means two inches will have a combined R-value of 6.28. Some manufacturers put the combined R-value on the packaging of their products, meaning they also take thickness into consideration.
The type of tiny house insulation you opt for also depends on your geographic location. Locations with dissimilar climates have different insulation requirements. If it’s a colder location, more insulation is required. With conventional houses, planning for insulation is easier to research with certainty, but insulation for a tiny house can be more tricky, especially if it is mobile. If in fact your tiny house is mobile, and you chose to move, you should choose a suitable location that was anticipated by the builder.
If you are trying to go green and help the environment (which is the case with plenty of tiny house enthusiasts), some insulation materials are more efficient and are made with an overall smaller carbon footprint.
The main concern with what insulation to opt for is thickness, more importantly how much space will be left after installing the insulation. For that reason it is very important to choose the right insulation option for your tiny house. Space is probably the most precious resource in any tiny house and it needs to be managed effectively for anyone who wants to be able to make their tiny house a tiny home.
How to insulate Your Tiny House
The first step to insulating your tiny home is to air seal it. Air sealing will do wonders for your home’s comfortability and how well your insulation will work. A sealed house with average insulation will actually perform better than a leaky house with excellent insulation. The most critical junctions for insulation are:
- Exterior penetrations
- Intersection of wall to floor
- Intersection of wall to roof
After air sealing every part of your tiny house, you need to do a blower door test to make sure everything is properly sealed. A blower door test creates low pressure inside of the house and lets you see where air is being pulled in. Smoke pens and thermal cameras can be used to see where the air leaks are. A great solution for air sealing is diy spray foam insulation.
The second step in insulating your tiny house are thermal bridges. Thermal bridging is where a material that transmits head crosses into or out of the conditioned space. An example ofr thermal bridges are wheel-well fenders on a tiny home that is built on a trailer. The walls around the fenders won’t be able to get as much insulation as the rest of your walls. The metal fenders will provide a path for the heat inside your tiny home to escape more easily. There exist solutions for metal building insulation, which help with:
- Preventing heat transfer
- Stopping condensation
- Stopping air transfer
- Acoustic isolation
- Stopping vapor
- Don’t promote mold or mildew growth
The next important step is learning the code requirements for your floor, ceiling and walls. This is mostly based on where you live, so some cities/towns will have different building codes. For moderate climate, the R-value needed for wall insulation is 15 and 30 for the ceiling insulation, but colder climates will require higher R-values.
After that you can choose which insulation option is best for your tiny house. When choosing the right insulation, there are two main concerns: can you do it yourself or do you have to hire someone, and your budget. The most important thing to know about insulation is that it pays for itself in the long term. The cost difference between cheap insulation and the best insulation is around $2000. Keep in mind that if you opt for better insulation, your power bill will be 30% lower each month, which could amount to saving thousands of dollars over the lifespan of the tiny house.
After choosing the right insulation for your tiny house, you need to be aware of vapor barriers. You want to control where water vapor can enter and exit a wall, roof or floor in any type of house. If you are effective with controlling which surfaces water vapor comes into contact with, you can effectively deal with mold in the long term. In general, you will need to put your vapor barrier on the warm side of the insulation, but that can cause complications. If the climate is constant (constantly cold or constantly hot), it’s pretty straight forward, but tricky climates that have a lot of humidity are in places that are very hot during the summer and cold during the winter.
Before installing the insulation be sure to prepare everything according to the manufacturer’s directions. There is a lot of science and technology involved in modern insulation. Because of that fact, it is critical to install it properly for it to work as best as possible.
Tiny house roof insulation
Roof insulation is very important, especially in tiny houses. Hot air is less dense than cool air, and because of that fact, it rises. That means the roof is a major location for heat loss. The height of a tiny house is a critical dimension because we can only build so tall. Generally, the most effective (hight R insulation) will go on the roof. If you choose spray foam for your roof insulation, you will need about 5.5 inches of insulation to make it R30+. A solid option for roof insulation is Prodex total 10M.
Options and materials for tiny house insulation
There are many options for tiny house insulation made from a variety of materials. These options include:
- Closed cell spray foam - R-value: 6 per inch
- Open cell spray foam - R-value: 3.7 per inch
- Fiberglass batt insulation - R-value: 3.1 per inch
- Rock wool insulation - R-value: 3.3 per inch
- Rigid foam boards (XPS, EPS, Poly ISO) - R-values: 5, 3.8 and 6.7 per inch, respectively
- Denim cotton insulation - R-value: 3.5 per inch
- Natural wool batts - R-value: 3.8 per inch
Closed cell spray foam is another insulation option for tiny houses. It has an R-value of 6 per inch, making it one of the highest R-value insulation options. Closed cell spray foam insulation is also a vapor barrier and an air sealer. Some of the options that incorporate closed cell foam are Prodex total 10M and Prodex total 5M plus. These products incorporate closed cell polyethylene foam sandwiched between reinforced reflective foil.
Fiberglass batts are one of the most common and economical insulations available. Because of the fact that they are widely used, economy of scale has driven down the price and now fiberglass batts are an affordable type of insulation. Fiberglass batts have an R-value of 3.1 per inch meaning that they are only half as effective as closed cell spray foam, but their cost can make up for that fact. A great option for fiberglass is acoustic wall insulation. The Prodex hybrid acoustic wall insulation is great at keeping areas acoustically isolated, as well as insulated and it even has a vapor barrier.