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Tiny House Steel Hold-downs: Simpson Strong Ties

The Simpsons…

Simpson Strong-Ties or steel hold-downs should be utilized in your tiny house build. They will do three things: make your tiny house a wind warrior (secure your investment), add a lot of time to your framing process, and tap into your pocket book. We ended up spending $850 for steel hold-downs along with the appropriate nails and screws to fasten them. Like the trailer, this isn’t a time to skimp.  If you use SIP panels, you may need to research for even more steel hold-down options. 

Subfloor Hold-Downssubfloor hold downsWall Assembly Hold-Downs

Steel hold-downs for tiny house wall

Roof Hold-Downs

Tiny House Roof Hold-downs

 

Proper Hold-Down Fasteners

Tiny house hold down hardware

 

Check below for additional pictures where you can see hold-downs utilized. The reins are ours,

Chris

 

Reflections, Hindsight, and Alterations:

  • Initially, I didn’t spend the money for the proper fasteners on our subfloor (a regret). There is a very big difference between the quality of Simpson’s nails and screws and regular ones.
  • We scored extra hold-downs from a builder friend, so I was adding a lot of 90 degree hold-downs to a lot of extra spots in the framing for additional structural integrity.
  • We saved a lot of money by getting certain hold-downs on online at Hardware Online Store. Make sure to check online store’s shipping rates–they can be game changers.
  • It feels really assuring to have the hold-downs throughout the framing!
  • Very few splitting issues with the nails. Sometimes, we pre-drilled holes for the screws. We mixed nails and screws in some of the hold-downs to get different types of holding power.

Additional Location Pictures:

You see can spacing of hold-downs in the subfloor.
Spacing and location of the hold-downs in the subfloor.

Added a plate and some corner hold-downs to the side wall.
Added a plate and some corner hold-downs to the side wall.

Added some extra hold-downs to the wheel-well area--figured this area is going to be pushed around!
Added some extra hold-downs to the wheel-well area–figured this area is going to be pushed around!

I didn't frame the top sill plate properly, so I'm hoping this hold-down ties things in well (used a stronger gauge to make up for framing mistake).
I didn’t frame the top sill plate properly, so I’m hoping this hold-down ties things in well (used a stronger gauge to make up for framing mistake).

Rafter hold-downs further strengthening wheel-well area.
Rafter hold-downs further strengthening wheel-well area.




Categories: Building, Design

Tiny House Subfloor: Flirtatious Beginnings: Wood Meets Metal

T&G: Tangible and Gnarly Plywood

After receiving our lumber, the plywood and wood needed to be acquainted, so we left the plywood on the trailer for a week to see if they liked each other…any gullible readers? I hope so. The first step was to correctly cut and lay out all of the plywood on the trailer without the obtrusive bolts complicating things (I’ll weld them on later). I mapped out two ways to lay the plywood efficiently. I did this before purchasing the lumber to help calculate my plywood count.  I ended up using a slightly adjusted “longitudinal” approach to make sure the plywood seams ended up on the trailer’s metal joists.

Trailer Dimensions:

Trailer Schematic
Trailer Schematic

Orientation Option 1:

tandg plan
Lateral Option

Orientation of Plywood Option 2:

Longitudinal Option

Confession: Permit-less Punks

If your trailer is a typical eight foot wide one, it’s a lot easier to lay out your plywood. Our trailer is wonderfully and awkwardly eight ft, four and 3/4 inches. With our roof overhangs we will be pushing the state’s limit of 8 ft, six inches. Because we rarely plan to move the house, we’re comfortable with pushing the width limit to gain as much interior space as possible. Will this “inch pinching” decision come back to haunt us? I hope not, gulp!

The Beginning of Endless Wood Cuts

Ignoring 100,000 demanding future cuts for the house, I emphatically engage with the initial large and heavy plywood puzzle.

Tools:

  • Circular Saw and Jigsaw
  • Powered Drill with Your Bolt Size Bit (5/8 in) *A little bigger
  • 4 ft and 2 ft Square
  • Cutting Guide with Clamps

Plywood Puzzle
Plywood Puzzle

Jigsawing the Wheel Well
Jigsawing the Wheel Well

It fits!
It fits!

Turmoil Already

Unbeknownst to me, after the wheel wells–the trailer starts to taper as you approach the angled hitch area! So, it wasn’t square and flush with my plywood’s factory edge pieces–which was really throwing me off. I thought the whole trailer might be out of alignment and warped. Panic anyone? Because my glass is half full, the trailer tapers only a half an inch on each side gradually over the last four feet–not so bad, so instead of moving the whole house’s frame inward, I tossed the dice, letting it hang over (the bottom plate will still be 85% on the steel frame and bolted to it). Surprisingly, the turmoil led to an idea.

Inch Pinchers Become Foot Pushers

“This overhangs. Why not gain some feet in the front? Extend the overhang!” exclaimed Chris.

“Wow. The extra feet would be nice! Would it effect turning and driving the trailer?” Michelle said.

“That’s what I was wondering about…I don’t know. If we only do two feet, it shouldn’t, but I don’t know. Should we go for it?” Chris said gazing at the hitch area while day dreaming about even more space.

“Yea!” Michelle said…day dreaming about more space.

Let’s hope our space ambitions really don’t haunt us–but yes, although in all of my tiny house research I have never come across any instances or examples of it, Michelle and I have taken the risk of expanding the house over the trailer two feet. This will give us 22 ft total. The angled steel framing near the hitch is four feet in length, so we’ll still have two feet–hopefully this is enough for all turning we’ll need to do on the road.

The Dice Keep Rolling: Extending the House
The Dice Keep Rolling: Extending the House

Bolt Holes

Finally, I drilled holes where I plan to weld the bolts. Had to buy a drill bit that was slightly larger than the 5/8 inch threaded rod. Initially, I was using a 5/8 inch bit and spinning it around to make a larger hole–not something my arm wanted to do sixteen times–doubt the drill liked it either.

Always ruining things with  holes!
Always ruining things with holes!

The reins are ours,

Chris

Reflections, Hindsight, and Alterations:

  • Although the extra space will be nice–the extra width may cause a lot of problems while driving–and it makes more wood waste because it’s over eight feet. Would have enjoyed an eight foot wide trailer for its simplicity.
Categories: Building, Design

Tiny House Subfloor Design: Bottom Up! Subfloor Evolutions

Initial Conversations

“Yack, yack, yack,” said the subfloor generic lipitor.
“Wait a minute. What do you mean?” responded Chris.
“Bolts, maybe.”
“Maybe?”
“Sure.”
“Have you heard of steel hold downs? What are they?”
“Ya, ya, all the time. They’re steel. They hold down stuff, ya idgit.”
“I give up.” Chris concluded.

Thermodynamic Obscenities

Common sensibly, fastening your house to the trailer needs to be well engineered and figured out.  After consulting countless tiny house builders’ experiences, I found 2cycle2gther’s article and the Tiny House Blog’s Phase 1: Subfloor Sandwich System to be extremely helpful.  Although we wanted to incorporate that precious 6 inch space between the steel trailer’s framing members, Michelle, a building science graduate student, informed me that steel framing (studs) destroy your insulating capacities where you’d want it: under your toes in the winter. Joe Lstiburek, building science guru, states, “insulating between steel studs is a thermodynamic obscenity.” Because there’s no way to fully enclose the trailer’s hitch from the elements, the trailer frame space wouldn’t be a part of our subfloor.

Redundancy Employed

Exemplifying redundancy, we’re combining an altered sandwich system with 2cycle2gether’s sheathing to trailer screwing as well as screwing the entire subfloor to the trailer with Teks #12 (wood to metal 2 3/4 inch screws). We will also weld 16 bolts to the trailer to hold down the sill plate and entire subfloor to the trailer.  No chances have been taken! Why choose some approaches when you can employ every single one?

Longest Sandwich Creation of My Life

Our Sandwich System
Our Sandwich System. Yum.

Bottom Bun: Galvanized Steel Flashing

The bottom bun of our subfloor is galvanized steel flashing (seemed like the stronger and better option than aluminum although it was a little more pricey). As I understand it, the flashing will keep out insects and provide some water protection. You can skip the flashing and paint the 3/4 inch plywood layer with a strong and nasty marine grade of paint…if you’re into nasty.  What’s strongly stated with flashing types is aluminum reacts poorly to the chemicals used in pressure treated lumber. Our bottom T&G 3/4 inch plywood is treated, so aluminum was a no go; however, galvanized steel isn’t flawless according to the web, so for safety, we used tar paper in-between the plywood and flashing.  As always, better safe than sorry.

More Steel!
More Steel!

Portobello Slider: 3/4 Inch T&G Plywood

The 3/4 inch tongue and groove provides a lot of structural integrity. Having it or one side of it treated supplies extra durability if water penetrates.

It fits!
3/4 Inch T&G Pressure Treated Plywood

Tomatoes and Pickles: Glulams and Foam

On top of the 3/4 inch plywood will be the framing of the subfloor. I will use homemade glulams and 2x4s and glue and screw them to the 3/4 inch plywood underneath. Additionally, 90 degree steel hold downs will secure everything to everything. Insulation will be foam boards–and all remaining seams will be spray foamed in. I’ll use 16 inch on center joists–this may be a waste of wood–but I’m playing all of my structural integrity cards.

Framing Style
Framing Style
No Decomposing Insulation
No Decomposing Insulation

Top Bun: 1/2″ plywood

On top of the framing will be only 1/2 inch thick plywood. Because the insulation is rigid, 3/4 inch plywood on top wasn’t necessary. All seams and joints will be caulked or siliconed for top notch air sealing (one of the most important, if not the most, energy efficient measures for a house).  This plywood layer will be glued and screwed to the framing.

1/2 Inch CDX Plywood
1/2 Inch CDX Plywood

Side of Chips: The Welded Threaded Rod

Choosing the way to bolt the trailer was stressful. We didn’t use bolts because our steel is 6 inches thick and the subfloor was 6 1/2 inches; buying 13 inch bolts would have been expensive; however, it’s a good way to prevent welding cost (unless you weld them yourself–threaded rod is cheaper). We placed the bolts in obvious spots: corners, near the wheel wells, and in-between those areas. We decided to weld the bolts (threaded rod) for added strength. We’ll use Simpson’s HTT5 hold downs with the bolts, so that’s a huge cost in itself. Although on a tight budget, these were the areas we wanted to spend our money.

Threaded Rod!
Threaded Rod!

Future post will have detailed specifics on each of these sandwich steps. Yum, yum.

The reins are ours,

Chris

Categories: Building, Design