Framing The Floor Of My Tiny House

Framing The Floor Of A Tiny HouseToday I wanted to share with you all on how I framed the floor of my house. The floors of your house in the floor is made up of a few sections:

  • Trailer decking
  • Sub floor framing
  • Sub-flooring
  • Finished flooring

Trailer Decking:

The trailer decking is the base that you’re resting your sub-floor framing on, which makes up the bottom portion of your flooring system.  Between the decking and the actual framing you want to have two control layers: a vapor barrier and a animal/bug barrier.  For this I used galvanized flashing sealed with a flashing caulking an stapled down.

This helped to block moisture from engineering in, but also kept road debris out.  Additionally this prevents pests and rodents from coming into too, but having a contiguous layer of metal to block them.

tiny house deck flashing

After that I added a single layer of 10 mil poly plastic sheeting as an extra control layer for vapor and air on top of my flashing.

tiny house floor vapor barrier

Tiny House Sub Floor Framing

My tiny house sub floor framing was done with treated 2×4’s placed on 2 foot centers.  The trick to framing is to have all your joists designed to be on 24″ centers, so when you place sub flooring – which is 4 feet wide – you know exactly where to screw into the floor joists.  The other thing you need to consider is the forces that the floor is going to be encountering, this effectively is your foundation, so it’s important for this to be really strong.

tiny house sub floor framing

To add more strength I used corner braces that are used in hurricane prone area building, I also tied the floor joists to the deck of the trailer using high sheer strength screws.  I screwed from below the trailer, through the trailer decking, into the joists.  In certain key joints  I chiseled out notches for the cross members to sit into, this wasn’t in the plans, but I thought the potential forces seemed to call for it.  Here is a video and then a bunch of photos after that.

My Tiny House Floor Framing:

Framing the Floor


Framing the Floor


Framing the Floor


Framing the Floor


Framing the Floor


Framing the Floor


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  1. Ryan, love how careful you are working. I am glad when you point special items out, wish you could cut the music out, i find it distracting but that’s just my opinion. You are doing a good job both building and videoing. waiting for next steps.

    • yeah the music was a little loud in this one, I tried to tweak it, but still wasn’t quiet enough! Thanks for the kind words!

  2. Keep up the good work and good luck with all! What’s the underlayment you’re using? Over ply too?- can’t tell. Have a good weekend

    • The layers will go something like this. Trailer deck, metal flashing, 6 mil vapor barrier, treated wood framing filled with foam, then plywood subfloor.

      • typically in house design (with heating) any vapour barrier is on the inside (warm side- just under the drywall in an insulated wall) thus if the floor space is insulated, the vapour barrier by code should be just under the flooring or subfloor, otherwise moisture will be trapped inside potentially leading to rot and mold issues. I hear in the southern states it is done opposite due to air conditioning so depending on location of your home be careful of vapour barrier placement.

        • What if the tiny home is built in Florida and permanently moved to Wyoming? Which option is better?

      • You are doing an amazing job, love your detailed photos! What thickness of ply are you using? Is ply sub necessary if you want to have .75″ tongue/groove flooring? I know weight is a big factor in building a tiny house to go…

  3. Ryan, what do you think the complete weight on the trailer will be? Thank you for videos.

    • Hey Joe,

      My estimate is around 6,600 lbs including the trailer. With the plans I have the houses usually come out to 6,400, but I left all the decking boards on the trailer so that will add about 200 lbs to it all. My trailer is rated to 8,000 lbs.

  4. Ryan, do you have a estimate of what the weight will be on your trailer when finish?

  5. Hi Ryan

    I have read your blog with interest. After having spent about $30 for E books on building these tiny homes, I realize that YOU should document YOUR process item by item because I love your attention to detail. You seem to really know what you are doing.If you decide to produce a E-manual I would be sure to buy it from you!
    Keep up the good work.

    • Where can I follow your building process…….???

  6. Ryan, i need to ask you a quastion? I try to do it as i sell to some of this progect to some of my friends. There is a need of constraction ingeneer and architectual for me to be able to transfer the trailer as a camper trailer, so i will need to have it wi PTI. DMV regolation? And plus i live in california, and i know you cannot live in this property or rent them out but you can used it as a regular RV. There is any problem that i do not consider that may some body find difficult to do it in the state of CA? Thank you very much and very good job.

  7. you said you were putting 6 mil vapour barrier between the flashing and the framing…. normally vapour barrier goes on the warm side (between framing and plywood..)

    • Is the purpose of the vapor barrier (in this case) to prevent contact between the flashing and the treated wood frame, so that the copper in the treated lumber can’t corrode the aluminum?

  8. Hi Ryan,
    I’ve been following your blog for the last 6-8 months now. I’m in the process of making my plans right now to build on a trailer.

    My question: I live in Canada (North of Montreal, Qc). winters are sometimes pretty cold. What kind of insulation for the floor would you suggest? I know I will be parked for a while so I can “close” the surroundings of the under trailer. Thanks for your great work, this ton of informations!!! 😀

  9. A suggestion… How about pre-drilling some passage holes between the compartments formed under the floor by the framing? Easy to do when the frame is open and they could be very handy in the future if one decides to snake utilities under the floor.

  10. Great details and photos. Makes it seem as if most anyone
    with some carpentry skills could do this. Love the idea
    of the holes in the floor beams while there is good visibility,
    maybe even flexible conduit with map so once finished you
    could know just where you could find a place to run any type
    of wiring of lines you may want in the future.

  11. I thank you for the valuable information and the music it’s nice and calming, does not bother me at all, plus the info is free.

  12. Love your website and all the detailed videos, I wish you could continue with your posts/videos and details. Thanks for all the free information.

  13. Hello Ryan,
    Your descriptions and photos are excellent.
    If I may offer a suggestion – the anchor bolts
    are shown with nuts but not with washers.

    • Hey Mel!

      Yes you are correct. The nuts here are just there so I didn’t loose them. I later used washers after the sub flooring, wall framing and the wall tie downs were in place.

  14. Do you have any more of the building process up yet?

  15. Hey Ryan
    Everything looks great! very detailed and helpful. I Was curious if my 2007 Nissan Fronteir Nismo King Cab could pull a tiny home this size? It has a towing capacity of 6,500lbs.

  16. should consider at least a 16″ on centre to avoid sag and/or bounce.

  17. Is there a reason you used 2×4 instead of 2×6? I thought most framing on floors is 2×6 material, maybe its because its straight to the trailer bedding? Thanks!

    • 2×4’s is plenty since they rest directly on the trailer bed, they aren’t really spanning anything. plus it gain us 2″ that we can use to make the loft a bit taller

  18. If weight is a concern why not use the trailer itself as your flooring joist? It seems framing over the trailer is redundant. Yes it would require drilling into the trailer frame to add joists where needed for 16″ on center frame. Joist hangers could be used. I’m obviously missing something. Could you please enlighten me?

    • Tammy,

      Some people build as you suggest in order to maximize the interior height. There is a downside though, there is no thermal break that prevents the cold trailer from transferring cold/heat into the floor.

  19. If someone were to build that thermal break UNDER the trailer floor rather than over it, would that work to prevent transferring cold/heat into the floor of the tiny home?

    Both of us are pretty tall, so any way to save vertical inches is a bonus.

  20. Hello Ryan

    Nice job, may I ask about the length and width of your house frame? I am in south Africa, just curious how much you paid for the trailer? Best for your project, thank u alex

  21. I would like to incorporate floor storage. Maybe about a foot or more of storage depth. Could the floor be constructed the same? BTW I love your book Tiny House Living!

  22. Really nice video and great pictures. You explain the process very well.

  23. What did use under the 2×4? It looked like a white plastic to seal the bottom. How much does it cost and where do you buy it? Thank you very much.

  24. What do you estimate the finish cost to be……???

  25. Hello, I was just wondering if you notice your floor sagging or creaking at all due to the 24″ o/c floor joists?

  26. My plans call for very similar subfloor construction, and I already bought my trailer. But the more I research, I’m terrified of condensation and rotting in all the spots where the wood floor joists touch the metal trailer. Years later, have you noticed any problems with that? Maybe using the treated wood helped? Thank you for all the great info you put out!

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