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Thread: Ground prep for cabin?

  1. #1
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    Default Ground prep for cabin?

    I selected my cabin site and did some test hole digging. The site it 8-10" of tundra the 6-8" of hard compacted dirt then gravel. What do you guys think? I'm thinking scrape it down to the gravel but then I need to haul in some gravel to fill it back up. I'm wondering if it would be acceptable to just scrape off the tundra and add gravel on top of the dirt? The gravel is going to be loose beach gravel that I have to haul by hand about 130'. Thinking maybe that dirt would be a good medium to kinda lock the loose gravel in place? The cabin is going to be 12x20 built on 2 rows of 5 pier blocks with a 4"x12"x20' beam on each. Any input/prior experience appreciated.

  2. #2

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    I would only pull the tundra and put gravel right where each pad is going to be. Less material to move.

  3. #3
    Supporting Member iofthetaiga's Avatar
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    If it were me, with that good gravel just below the surface, I'd just clean down to the gravel in the spots where my cribbing or piers need to go and place them directly on the undisturbed gravel. No need to haul anything from the beach. (And I know you didn't ask, but I prefer treated wood cribbing or large concrete block for piers. I detest those little concrete pier blocks with the spindly all-thread rods in them. Those things are made for supporting little patio decks in your backyard, not for supporting buildings).
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    Member ChugiakTinkerer's Avatar
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    @ Kandiyohi Kid,

    Iofthetaiga makes a good point about the poor suitability of concrete pier blocks for putting a cabin on. Each of those blocks has a total area of about 1.0 square feet for load bearing. If your cabin is going to be on the heavy side, especially with perhaps a few feet of snow on it, then you might want more square footage in your foundation making direct contact to solid ground.

    Edit: Forgot to mention, if you want to build back up to the tundra grade then the beach gravel will be fine. It should be compacted though, and you may need to put a 2x frame around each dug out area to keep it from eroding away.

  5. #5

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    You want to get down to the gravel to support your foundation. The gravel is a non-frost susceptible soil. It will properly drain moisture and then during the winter time your ground will not frost heave. If you build on dirt, in particular clay dirt which is horrible drainage, it will soak up the moisture like a sponge and your foundation will heave several inches in the winter. Do like Taiga said and dig down to the good gravel. You can always build back up to whatever grade you want to with proper cribbing.

  6. #6
    Member cdubbin's Avatar
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    The pier blocks would work fine but they are pretty shaky....what I would do personally in your situation is dig a couple parallel trenches, lay in some road fabric, fill with gravel, soak and tamp it, then lay a couple 8 x 8 x 20 AWW skids down and build on that....easy to move, easy to re-level if necessary.
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  7. #7
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    Thanks for all the input. I have to haul everything by boat after trailering down a unmaintained road for 10 miles. The pier blocks are already there so kinda committed. I'm using the 4x12x20 so I only have to brace side to side and plan to brace those with the floor joists(2x12) so should be solid. Just 12X20 with 1/2 loft 12/12 roof so not a huge structure and shouldn't hold a bunch of snow.

  8. #8
    Member nooksack's Avatar
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    The snow load is not a concern as the ground will be frozen more than likely at that time. It is in the spring when the soil turns to mud and the pier blocks settle into that mud. In the fall as that soil expands as it freezes it will heave your structure up. In the long run removing the 6-8" will be much less labor and hassle than not removing it. If the gravel is clean and drains well 4 piers per side will be fine. That is just my opinion ands hat I would do with what you have. Sounds like a fun project.

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