Insulating your tiny house

There are three different types of insulation I considered for my tiny house;

Spray foam – I thought this might be the best choice since it has a high R value and there would be no leaks (since it is sprayed in to all the nooks and crannies). The reason I ultimately decided against it is because this is not a DIY solution and thus likely much more expensive.

Fiberglass – I’ve worked with fiberglass before and it is fairly inexpensive and very easy to install. The problem is it doesn’t have the highest R value (~ 3.4 per inch).

Styrofoam Boards supplemented with spray foam – This is a little more expensive than fiberglass (I’m not sure exactly what the comparison is) but has a much higher R value of 5 per inch. This was my choice because I thought it was the next best thing to pure spray foam and it was something I could do myself.

After working with the Styrofoam boards I think my decision might have been flawed, and in hindsight would have chosen differently. The first and most important reason is that while the R value of the Styrofoam is much higher per inch, the boards that I am using are 2 inches thick, thus giving me an effective R value of 10. If I were to use fiberglass, I would fill the entire wall cavity and thus have an effective R value of 12. Couple that with the ease/speed of installation (the boards are a huge pain and mess to work with) and the lower cost I think fiberglass would be the way to go for warmer climates (my TH is headed to Florida). For colder climates I think I would spring for the spray foam insulation.

This is something that needs to be done right the first time since it isn’t easy to change out. I would love to hear any opinions.

Fun fact: While researching R values I read that 1 inch of insulation is equivalent to 30 inches of concrete!

UPDATE: I have since worked with the styrofoam more and experimented with different cutting tools (circular and hand saw) and no longer find it as difficult to work with. I also got a better tool (Hilti) to inject the foam into the cracks. In addition, if I had used 3″ foam my R value concerns would be alleviated as well.

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