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Journey
Member
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# Posted: 6 May 2025 12:04am
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Hello!
I'm building a 12x20 tiny house on 4x4 skids for myself. The thing is I can't find 20ft long skids. So I'm planning on using two 10ft skids. The will be on 8x8 concrete dobie blocks with the straps.
The problem is I won't be able to bolt both ends of the skids on the block straps without drilling right through the seam. Would bolting one skid to the strap and nailing the other be strong enough? Would it be worth tying the two skids together with Simpson Strong-Tie straps too?
Also, another question: would 2 skids on either side (1ft in from the edge ofc) work, or should I go with 3?
I'm doing all this mostly by myself, so I want to make sure I get everything right.
Thanks for any help!
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gcrank1
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# Posted: 6 May 2025 06:59pm
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Iirc 4x4 isn't near as strong as laminated 2x plank skids vertically beneath. And I dont mean 2x4s lam together.
We have folks here with real knowledge; as for me, just a guy who has built some stuff, 4x4 seems too small for a 12x20 and we dont know anything more about the structure than that footprint.
More info needed!
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spencerin
Member
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# Posted: 6 May 2025 10:36pm
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Where are you that you can't find 4 x 4 x 20s, or 4 x 6 x 20s?
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Brettny
Member
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# Posted: 7 May 2025 07:40am
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I have 4 6x6 skids under a 10x14 shed. 6x6 skids even bend a bit.
Go to a private lumber yard to get lumber longer than 16'. They will have it or steer you to some where that does.
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Desim
Member
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# Posted: 7 May 2025 12:35pm - Edited by: Desim
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The Lumber yards here (Tennessee) don't stock over 16' but they can get them for you.
I had to do this with Christian Cross materials.
edit: I used 6x6.
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DRP
Member
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# Posted: 7 May 2025 01:37pm - Edited by: DRP
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4-6" is too close to the ground for untreated wood. You may be planning on treated joists ply, sheathing etc. Its sounding too low.
8"x8" spot supports.. hmm half a square foot each. What is the weight being supported and the bearing capacity of the soil. In other words those are going down till the wood is in full contact with the soil and hopefully, probably, it'll have enough contact down to be supporting then without sinking further.
One way would be to dig a perimeter trench to frost depth and fill it with crushed stone up to grade. That should control frost heave. The a "log cabin" pen of treated 6x6's 3 or more courses high. Use the long fastenmaster type screws to secure the layers and corners together into a solid crib. In that scenario I'd use, roughly, a 16'+4' on the 1st layer. A 4'+16' on the next and then some other lap on the 3rd layer. Overlap the corners and pin them together and you are creating a rigid crawlspace out of treated material on a gravel footing. If there were mobile home anchors in the bottom of the trench with the straps coming up the to top of the crib I believe you would have satisfied code and the basics of support- up, down and sideways.
Remove organic matter inside the pen and lay down plastic to keep ground moisture from percolating up. Should be rodent proof but you could pour a thin "rat slab".
Cantilever, the "rule of thumb" is no more than the depth of the joists. 2x8 joists, 8" max cantilever. There is a table if you want to go further, read the footnotes. Also think about the other rule of thumb, a 1:1 aspect ratio isn't going to blow over. If you're staring down a Helene you do not want a candy ash stance.
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