Tiny House Progress Report – Trailer Prep

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Prepping the trailer was quite the project. It took roughly two and a half weeks to complete, working intermittently around the weather and other responsibilities. I’m going to share what this process was like- the unique challenges we faced, how we overcame them, and suggestions for other tiny house builders.

Trailers and tiny houses

Choosing the right trailer is perhaps the most important decision you will make. It’s the foundation of your home. It can also be a huge time/money suck if you don’t choose/fabricate the trailer with the right features.

Decision #1 – New or used

I ordered a custom trailer, fabricated specifically for my tiny house. I tried to find a local trailer manufacturer to build it for me (in Manhattan, KS or nearby), but unfortunately the closest I could find was Retco Trailers- 7 hours away in Sikeston, MO. On the plus side, Retco has been making tiny house trailers for several years and I was confident that they would build me a trailer fit for a home.


Big bummer #1 – Not getting the trailer you ordered

I sent them the engineering plans for a trailer, provided by http://www.tinyhousebuild.com, to the exact dimensions and features I wanted. Unfortunately, it was not built to these exact specifications. The two biggest differences were #1 – Lack of anchor bolts (to anchor the frame of the house to the trailer) and #2 – The depth of the floor joists (they were 3″ instead of 4″).

Floor joists

The reason I ordered the floor joists to be 4″ was to have enough room for insulation between the joists to meet the R-value suggestions for a floor in my region of the country (R25-30). They built 3″ joists. Therefore, we had to find a way to increase the depth of the floor.

To do this, we used carriage bolts to attached treated 2x6s to each of the existing joists. This had two advantages.

#1 – The floor joists were now 6″ deep, creating even more space than originally expected and allowing for more insulation options

#2- gave us a wood frame to nail/screw into with the subfloor and flashing that would cover the top and the bottom of the floor. Win-win!

It took a week to get all those bolted in. Drilling into metal is hard. We went through several drill bits. In the end, tho, I think it was worth it, and saved us a lot of time and energy by being able to screw the subfloor and flashing into wood rather than into the metal frame of the trailer.

Anchor bolts

The anchor bolts were not included on the trailer. The anchor bolts secure the frame of the house to the chassy of the trailer. This prevents the house from falling of the trailer when you’re driving down the road. Kind of important.

The options to address this were to a) have someone weld the bolts onto the trailer (which costs a pretty penny) or b) install some kind of bolt/anchoring system on our own. We are opting for option ‘b’, but still have not yet installed the bolts. We will likely drill/bolt some hurricane clips into the subfloor.

I am still disappointed that the bolts were not included, per my specifications, but in the end if gives us some room to adapt/tailer our anchoring system to the design of the house, which has been slightly altered along the way.

Decision #2 – Type of insulation

We had 6″ of floor space to work with. The regional specifications for R-value in this area is between R25-R30. We had a few options available in our area: Rigid insulation or fiberglass. In the end, we went with regular R19 fiberglass insulation (the pink stuff). We estimate the R-value of the floor to be right around R25, with the subfloor, wood flooring, and flashing underneath the trailer.

There are many other options, but we were on a tight time frame and didn’t want to order insulation and wait for it to arrive. This impacted our ability to build sustainably (some insulations are more environmentally friendly and have a lower carbon footprint than others), but it was a trade-off that we ultimately felt like we had to make.

Decision #3 – In-floor storage

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We made some adaptations to the original design of the house that eliminated a lot of storage (e.g., cabinets) to help open up the interior. To compensate for this, we decided to build some in-floor storage into the floor. Brady designed and built a box that would sit underneath the floor, resting on the frame of the trailer, and that would not go any lower than the lowest part of the trailer. This gave us confidence that the box would not create more of a hazard when driving down the road and have the potential to get caught on a speed bump or something of the like.

The box is roughly 4×6 and 1ft deep. It will sit in the living space and will likely have several piano hinges to make for easy access. We could not use R19 insulation to insulate the box, so we opted for a combination of rigid insulation and bubble insulation, giving us a very thing layer of insulation with high R-value that wouldn’t take up more storage space in the box.

Lessons learned

  1. Check and double check the specs of your trailer if you are having one fabricated for you. Make sure the fabricator knows exactly what you expect and what you want. This will save you time, money, and energy and will allow you to build the subfloor much more efficiently.
  2. Check the recommended R-value for a floor in your area (see http://www.greatdayimprovements.com/insulation-r-value-chart.aspx)
  3. In-floor storage is possible and (hopefully) a great way to utilize space underneath the house that would otherwise be inert. It takes some extra time, but in the end, I think it will be worth it.

What do you think of this design? What are others doing with the trailer/floor? Please leave your comments below!

2 Comments Add yours

  1. fulllifemadesimple says:

    Hi! Great article I agree the trailers so important since it’s the foundation for everything else. I ordered mine from iron eagle trailers in Oregon and had good luck. Very helpful and great customer service.


  2. Meg Harper says:

    I’ve been watching this tiny house trend with interest. Sounds like something viable for the future. But where do you set it down? Most smaller, rural tracts and all subdivisions have ordinances regulating size and placement.


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