What’s Wrong? Tiny Home Trailer Video

This topic comes from a custom trailer builder we work with.  He asked:  “Will you please look at this tiny home trailer video?  I have a customer that wants me to build one like this – with insulation cavities and 1/2″ anchor bolts.  They want a triple axle trailer at 21,000 lb. GTW like in the video.  What do you think?

Well, the internet has certainly created a market for information.  All kinds — both good, and misleading.  All the platforms (Google, YouTube, Facebook, etc.) encourage publication, but don’t vet it.  That means a wealth of information at our fingertips – which is Wonderful!!  BUT, Who should you believe?

The Tiny Home market, unfortunately, has a lot of misinformation and opinion floating around.  We are not immune to the streams of curious reporting like in this trailer video.  Every once in awhile we get a request like this, where I think it’s worth sharing the answer.  So, here we go.

Best Of Intentions?

I want to start by complimenting the video creator.  He obviously put his name and face on the line, which is admirable.  He is trying to share things he feels others might benefit from.  His heart is in the right place, but his knowledge?  Perhaps not quite there, yet.  I believe he is sincere, though at the end he shares the ulterior motive in wanting support for his build.

The request for support may or may not be a red flag, but it’s something to consider.

I don’t wish to speak disrespectfully – because in truth, his sharing of information is not that much different than what we do here at MechanicalElements.com.  (The big difference is years of engineering experience.  That doesn’t mean we know everything, but hopefully we can shed some light.)

Let’s start with that.  I do not wish to disrespect, but to enlarge knowledge.  The video is a few years old, so I’ll bet even this young man has a different perspective now.  Perhaps, if you are embarking on a Tiny Home trailer adventure, we can give a little additional perspective that is not in his video.

The Tiny Home Trailer Video

Here is the youtube link:  The BEST Trailer for a Tiny House!  Full Review of the STRYKER – YouTube

The guy in the video certainly makes some statements that sound authoritative, but by his own admission he is new.  We can also see that in how he explains the trailer.  This is Caution Flag number one:  Giving advice when you’re new to the subject.

Second, throughout the video he repeats the sales lines from the manufacturer that he ate hook line and sinker.  (Yes, I have heard similar lines from sales folks before.)  When I ask the question above, “Who do you believe?”, I’m talking about much more than just internet media.  This is Caution Flag number two.

Here is my quick response to the trailer builder that sent me the video.  “The video makes some good points, but please help your customer learn a little more about some of these tiny home trailer features before believing everything in a video from a first-time trailer buyer.”

Yes, that can sound a little rude.  I apologize.  However, let’s look at some of the claims.

Trailer Length And Capacity

The tiny home trailer in the video is 28 ft long, built with 6″ x 2″ rectangular steel tube main beams.  He does not say the tube wall thickness, nor does he show full construction under the trailer.  While that does leave questions, I have seen many trailers like this, and they are insufficient.

Frame Strength?Of course, he would not know that.  Customers are not expected to know that.  When you touch the trailer, it certainly will feel “super strong” as he says.  We expect the manufacturer would do their engineering.

Really?  If that sounds bold, please look around our website and note the samples of engineering analysis in images.  I have analyzed many trailers, some very similar to this, and there are two big, related problems.

  1. For a tiny house, trailer frame flex is usually (should be) the design limit.  Flex is the frame bending, but not permanent – like a spring.  A long trailer will flex a lot before it permanently bends.  So, I don’t think the 2″ x 6″ construction of his trailer will break.  However, if he puts anywhere near 21,000 lb, it will flex, a lot, especially on a bumpy road.  That makes a high risk of damage to the house.
  2. The trailer appears to have the same 6″ x 2″ tube around the perimeter.  It’s good for those areas, but it means you have a stiff-ish front, a flexible center, and a stiff-ish rear.  The weakest part of the trailer frame is at the point of highest stress.  (Right over the axles.)  That is poor design, because it means the house will flex most right in the middle.  Ouch.

I’m an old farm boy, so for perspective, the construction here is similar to a 28 ft hay trailer.  For hay, it does not matter if it flexes, because the hay does not care.  On the other hand, do you want your house flexing like that?

IMHO, Building a tiny house trailer with the specs of a “hay trailer” is just cheap, bordering on irresponsible.

In Contrast:

Our Mechanical Elements Tiny Home Trailers are I-Beam construction.  It is a little different at 32′ (instead of 28′), but the stiffness of our trailer is about 8 times more.  In common terms, that means our trailer will flex 1/4″ when the trailer of the video will flex 2″.  That’s huge for your house.  You can read more in this Tiny House Foundation article.  Yes, the stiffer trailer is a little heavier, but do you want your house built on a flexy foundation?

I will point out that house exterior walls add stiffness, so the trailer frame is not the ONLY piece in the equation.  However, the added stiffness is really hard to quantify.  Stick built walls add much less than, say, SIP panels, for example.  (Assuming SIP panels are designed for strength, then both oriented and connected in a strength promoting fashion.)   If you wish to depend on wall stiffness for strength in your trailer, be very purposeful in the way you construct the house.  Doors and windows, for instance, diminish potential stiffness gains.

Tongue Strength

Along the same line of thought, it appears from the video that the tiny home trailer construction for the tongue is the same 6″ x 2″ rectangular tube.  Again, from engineering experience, a tongue that long with 6″ x 2″ tube at 21,000 pounds is a huge Red Flag.

Tongue ConstructionWe normally recommend 10% – 15% tongue weight for stable towing.  12% is usually a good target.  With 2100 lbs at the ball (10% tongue weight, minimum recommended) or 2500 lbs (12% target), I expect problems.  If you do the wrong thing when driving, or find the wrong bump, it will bend the tongue.  Here is an example of a weak tongue that bent.  Yet, according to the specs, it was not overloaded.

Granted, the manufacturer may recommend a lower tongue weight, I don’t know.  But that probably means sacrificing stability in order to make the trailer cheap.  Is that a good trade-off to you?

For the video, in his situation, if 21,000 lbs. is way overkill, then perhaps he is OK.  However, IMHO, it is not OK for a manufacturer to build a trailer for 21,000 lb and not provide a tongue to properly support it.

For almost all trailers, the point where the tongue meets the main frame is a very high stress area.  So many manufacturers shortcut this area, to the detriment of their customers.  I find it very disturbing that there are so many bent and broken trailer tongues.  In my humble opinion it comes from laziness on the part of the designers in not doing proper engineering analysis.

In Contrast:

Our Mechanical Elements tiny home trailers also use 6″ x 2″ rectangular steel tube for the tongue, BUT, double, in the area of highest stress.  Analysis almost always shows high stress where the tongue beams intersect the main frame.  It does not lie, because we see the failures from other manufacturers.

To assure our trailers are strong, we put strength where it is needed.

Tiny Home Floor Insulation

In the video he is right to emphasize the need for insulation under the floor.  However, he misses a very important point.  (And the way he says it, sounds like repeating sales propaganda which is, unfortunately, misleading.)

If he insulates between the cross beams and puts his floor on top, what is the point of the insulation?  He’ll have a thermal bridge at every crossmember and each main beam – giving him a cold floor.  The bottoms of the beams expose to the cold, so if all you have is a piece of plywood to insulate, then that’s a problem.  (Also noted by someone in the video comments.  Good job.)

He talks again about it later, but misses the point about thermal bridging of the cross members.  Steel is a pretty good conductor of heat, so you don’t want the supporting steel in contact with the bottom of your floor.

The “insulation pockets” he shows do not provide the insulation affect he is touting.

In Contrast:

Our Mechanical Elements tiny home trailers integrate the floor joists into the trailer frame.  It gives a low floor, while allowing a gap between the beams and the floor.  There is also a gap (to fill with insulation) under the cross beams.

From a theoretical standpoint, the best insulation is achieved by building floor joist above the trailer frame.  6″ – 8″ recommended.  However, reality requires a compromise.  In the video he makes a very good point about the height of the floor and how that relates to interior space.  I totally support the concept of integrating floor joists into the frame.  While it is not perfect, providing proper thermal gaps does a pretty good job of accomplishing both goals.  Unfortunately, the trailer in his video does not accomplish that in the way he describes.

Mounting Tiny Home Walls

I have seen 1/2″ studs to anchor walls like in the video many times.  They are usually standard all-thread which is lower strength than a Grade 2 bolt.  That’s probably enough, for many situations, but it will push the envelope in a windstorm.  If you choose to use them, make sure you have a lot, or use at least a B7 threaded rod.

Tiny Home Trailer Video StudsThat said, I don’t like the threaded rod studs.  I think they lack the function desired for a house, long-term.

Normally, these bolts hold wood.  Yet, wood changes over time, so you should theoretically tighten the bolts occasionally.  (Every few years.)  If that stud is in the middle of your wall, how are you going to tighten it without tearing a hole in your wall?  (And how will you remember where they are so you can tear the hole in the right place?)

Yes, this is a similar technique for some traditional home foundations.  But, houses built on concrete foundations don’t move and bounce, and they are not on the highway.  Personally, I don’t prefer this stud method for a tiny home.

In the video he mentions self drilling screws as an alternative to the studs.  I agree with him about that not being a good choice.  Self drilling screws are a lazy / amateur way to attach things for a tiny home, IMO.

In Contrast:

As a contrast, for our Mechanical Elements designs, we suggest a method that puts the bolt accessible, but hidden, under the trailer.  That way, you can walk around and tighten things occasionally.  It is also a much better attachment for wood, long term, as it spreads the compressive load.  We recommend it for structure stability and longevity of the house.

Video Indications of Tiny Home Trailer Inexperience

I was amused at the point in the video where he is explaining the things on the tongue.  What he says is correct, but some inexperience shows.  He doesn’t handle the hitch well, and he doesn’t realize the breakaway box is required.  (Should be on every trailer over 3,000 lb capacity.)  Sure, it’s a good idea, but the trailer maker put it there to meet the law.

He’s fascinated by a heavy duty tongue jack . . . . Why would he even discuss such a thing in a video about a tiny home trailer? – OK, it was important to him when purchasing, so probably important to other first timers.

There are many, many options for tongue jacks, ball couplers, chains, breakaway kits, etc..  Also many options for jacks under the foundation (a point he did not dwell on).  The items in this video are nice.  No complaint there.  Anyway, I am amused at the way this section is presented.

If you are buying a trailer, or building a trailer, take time to research the many options.  So many good ones are available.  Find the ones that meet your needs.

Summary of the Tiny Home Trailer Video

Again, I do not wish to disrespect the creator of the video.  I believe his heart is in the right place, and he seems sincere.

While he does not state his profession, I don’t expect him (or most people) to know the engineering.  Yet, when making a video, I believe it is his responsibility to know a little more than just regurgitating the sales pitch.  Videos like this, though well-intentioned, often mislead others who are also learning.  That is a personal pet peeve of mine, and it’s why I have chosen to write this article.

Coming from an engineering background, I see most salespeople don’t understand the essence of what they are really selling.  That makes it hard for us as consumers to weed through what is true and what is hype.  Yet, it is, nevertheless, our responsibility.

Yes, we offer Tiny Home Trailer plans, but selling plans is not the motivation.  I just want to spread a little better knowledge, and stifle some of the misinformation.  Hopefully, this article provides another perspective, perhaps some different things to think about, as you pursue the dream for a tiny home.

MechanicalElements.com
DIY Project Plans and Engineering Perspective so you can Build It Great!

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