That said, they recommend glass wool or fiberglass as a quality option for someone looking for an environmentally friendly insulation option for their tiny home. Another name for fiberglass, glass wool is probably what people are most familiar with when they think of insulation. It’s cheap compared to other insulations and widely available. It has one of the lowest global warming potential ratings of all batt insulations, Grotyohann said, and it’s made from mostly recycled glass material. “It can be tricky to install correctly, and respiratory protection while installing is a must,” she said. “A 2x4 wall will only give you R-13 insulation, less if the batts are installed incorrectly and are compressed or slump within the wall cavity.” R-value is the measurement of an insulation material’s effectiveness in terms of its thermal resistance. Tiny home owners Paul O’Connor and Annett Welss of Living Tiny and Green used glass wool insulation in their build and are happy with the results. “The house is nicely insulated from top to bottom which keeps us warm in the winter and cool in the summer,” Welss said. It costs around 25 percent more than fiberglass, but you’re gaining a higher R-value (R-15 for a 2x4 wall) for the cost, she said. Grotyohann finds it easier to install than fiberglass and much easier to cut around electrical boxes, wiring and plumbing without losing its full R-value. “One of the things I like about mineral wool is that unlike many other insulation products, it is potentially salvageable for reuse at the end of the life of a structure,” Grotyohann said. “Keep in mind that flame retardants may be added and pesticides may be added to wool, so if natural fibers are important to you, be sure to look into the additives in the product you’re using and their potential health impacts,” Grotyohann said. “But they are quite expensive, and again, you would likely need a flame retardant wall covering like drywall,” she said. “Although, that impact is lower if you take into account the carbon sequestered in the denim,” she said. Similar to sheep’s wool insulation, she advises that people consider that the denim or cotton materials may be treated with a flame retardant to reduce flammability. “It seems to be common practice to only insulate the roof, which helps to some extent,” she said. “But a house will only be really energy-efficient if it is fully insulated, airtight, has double-glazed windows, and is draft free.”Having built quite a few tiny homes, Grotyohann and Schulz said proper insulation isn’t only related to the insulation itself, but how you build the walls that makes a significant difference as well. “Minimizing wall framing minimizes thermal bridging and maximizes the space in your walls for insulation,” Grotyohann said. She also recommends paying attention to how you seal the walls. “Sealing all the wall penetrations around wires, plumbing, electrical boxes gives you a big return for very little investment of time or money, but is often overlooked by first-time builders.”
