Installing Tiny House Subfloor Flashing

Applying Flashing

Flashing is the bit that keeps out rodents and gives your trailer subframe a base to hold in the insulation. Metal Flashing comes in rolls from Home Depot or Lowes and is easy to unroll.  However, its full of sharp edges so gloves are a must and tin snips are a requirement if you want to cut it.  If you can, get the seams to overlap.  If you can’t, at least get them to join up over the wood beams.  I learned the techniques (far more than mentioned here) by watching the videos at Tiny Home Builders and this Tiny House eWorkshop.  Check em’ out.

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Basically roll the flashing out, staple it down to keep it in place (this is only temporary so it doesn’t need to be pretty).  Rinse and repeat. Once its all attached (this makes it sound faster than what it is and lacks the details int he tutorials) you’ll then add one step that wasn’t in the tutorials above.  Its a trick I did myself.

When attaching the frame to the subfloor the easiest way to do this is to:

  1. Before putting the frame sections back on drill a hole into the flashing (up through the bottom of the trailer beams) in each corner of each of the three frame sections (so 12 holes total).  No need to drill through the flashing for every other hole.
  2. If you are doing this yourself put two lag bolts just barely above the flashing surface (picture below) on the side where you have the frames on the ground.  You’ll just be flipping the frames over onto the trailer (they are heavy) and sliding them into position.  The two screws on the one side will allow you to position the frame in the right area.  You don’t want the screws on the opposite side of the trailer since you’ll be sliding the frame across that area.  Described in the video.
  3. Once you have the section with the four corners in place drill up the 4 lag bolts into the corners.  The piece is now lined up with each hole.
  4. Repeat these steps for each section
  5. Once all sections are in place crawl under the trailer and start screwing the lag bolts in.  If your drill is powerful enough you don’t need to predrill through the flashing.  If it isn’t, you’ll need to “pop” each hole open through the flashing.  The joist on the other side of the flashing is already pre-drilled so no need to go all the way through.

Enjoy the pix and vids below.


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