Tiny houses on wheels (THOW) are built similarly to homes on foundations except for that their foundation is a trailer, and their wall systems are typically thinner. Tiny houses are built with wood or steel studs that create a 4 inch thick wall, or they are built with SIPs (structurally insulated panels) that are also 4 inches thick. Most homes on foundations that are not constrained to the building dimensions of a THOW have a wall system that’s 6 inches deep or more.
The thicker the wall system, the more insulation that can be installed and therefore the R-value (insulative value) of the insulation can be higher. If the building is built correctly then the thicker the wall system with a higher R-value, means that the inside will stay warm in the winter and cool in the summer. The home won’t need to be heated or cooled as much and therefore will be less expensive and more comfortable to inhabit. It also depends on the climate that the home is in, and building codes will dictate the necessary R-value.
All kinds of insulation use the natural or man-made structure of capturing small pockets of air, which creates a resistant barrier that inhibits the transfer of thermal energy in and out of the space.
There are numerous different kinds of insulation that humans have used since we began to build structures. Originally, insulation was made out of natural materials that functioned well in the given climate. Building science has progressed and homes have become tighter with membranes to protect the insulation and stop airflow in and out of the house. We have also engineered different types of insulation, that vary in installation and material.
Tiny houses mostly use a few types of insulation, which we will go into below.
In the beginning of the movement tiny homes were built by mostly DIY builders and vapor open insulation that came in batts making it easy to install were common. Vapor open insulation means that air can transfer through the wall system and is beneficial in tiny houses because it’s common for humidity levels to be high within a tiny home.
The most common vapor open batt insulation for tiny houses are mineral wool, sheep’s wool, fiberglass, and recycled blue-jean.
Closed cell foam boards have rigidity and typically a high R-value. They can be cut to fit into the wall system similar to batt insulation. They are not vapor open, but can be a good option when insulating a narrow space and when a high R-value is needed.
SIPs are usually closed cell foam between two structural boards. On their own they are strong and create a different wall structure without the need for studs.
Spray foam or blow in cellulose has become the most common form of tiny house insulation. Especially for builders because it’s quick to install and has a high R-value. Most builders don’t install their own spray foam because it’s toxic to work with and must cure in a specific environment to function properly. A spray foam company that’s well versed in how to install is usually the best option and fastest way to go.
Clearly there are many different kinds of insulation and it depends on the climate, building style, and personal preference on which kind is best for your home. Tiny houses are on wheels and therefore could be in many different climates in their lifespan. It’s important to take that into consideration when building.
Written by Isabelle Nagel-Brice of A Tiny Good Thing