Insulating The Floors – Part 1

So in my last update I showed how I framed the floor (here) of my Tiny House and the next step was to insulate the floor cavity.  When you frame the tiny house, most people frame it so that it hangs off the edge of the Tiny House on most of the sides.  This creates a gap between the framing and the actual trailer.  So we use expanding spray foam to close it up air tight.  This foam creates a water and vapor barrier.

One major tip I can give you if you are using this stuff, wear latex/nitrile gloves that you can throw away.  If this stuff gets on your skin it literally will not come off, even with paint thinner, goo gone, pumice soap, or any other trick you have in your book.  You basically have to wait for your skin to wear off.  trust me, I know!

First off, this is what I started with, the floor framed, beneath that you can see the white vapor barrier and that is covering the metal flashing.   Then I sprayed the expanding foam into all the cracks to seal it up.  From there I will be putting in the foam board, which I will show in my next update post.






  1. Why would you used foam board instead of just using closed cell foam throughout the bottom?

  2. So the foam board I am using is closed cell polystyrene foam. If you are thinking of the spray foam for whole house stuff (not the small cans) I wanted to go that route. But I got 5 different quotes and the cheapest I could find was $2000 which isn’t in my budget. The way I am doing it here is almost identical R value and very close in terms of creating a seal air envelope. The difference being that it’ll cost me $500-700 to do the house versus the $2000.

  3. WOW I’ve only seen prices for an average size home so I really never imagined they would charge that much for such a small area. Definitely not worth nearly 4 times a much. I had a dream of building an entire tiny with SIPs or closed cell spray in foam but I doubt SIPs are cost effective.

  4. I was really floored by how much it was, most of the quote I got hovered near the $2700 mark. They now have some DIY spray foam kits, but that was looking like it would be close to $2,000 for me to do.

  5. Hey Ryan,

    Love to watch your progress. I’ll be building my own tiny something shortly.

    I do have a question totally unrelated to your project… the intro to your videos. It’s an awesome bumper, technically… but 30 seconds long? Many times your intro sequence is over 10% of the total length of your vids. I think 10 seconds would be more than adequate for proper branding. No?

    Not trying to offend… just offer constructive suggestions from the perspective of your audience. 🙂

    • hey ryan-
      i so appeciate the videos being available. they’re very informative. but, ditto what dan said. :/

    • I tend to agree it’s too long, but I haven’t quite figured out where it would be good to trim down. The trouble with these animations is they are very complex to create and can be $$$ too.

  6. I think the intro is pretty nice/slick, but then again, this is coming from a guy with long intros to his videos as wel- lol. Worst case, people can just scroll by it. Its good, nice work Ryan.

  7. Love videos. Ryan, how do you fit/cut the foam board in with the spray foam there as it may be uneven in some places? And do you spray more with the foam board in place. I was wondering what the difference would be if you put the foam board in first and then sprayed in the remaining cracks? Thank you, these videos are much appreciated.

    • I just squished it in there and it worked out. I did go back after and fill in all the cracks with more spray foam once all the foam boards were in.

  8. Cool

  9. Hey Ryan,

    Love your website and Videos! The checklist is especially helpful as my Husband and I are in the “planning” stage of our tiny house. We’re going to the tumbleweed tiny house workshop in Orlando this weekend to learn more.

    My question for you is, why did you use 2 glued 2×4’s on the sides of your floor frame instead of using a 4×4?


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