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mystereons
Member
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# Posted: 12 Oct 2020 07:51pm
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Hi all, I’m new to the forum and really hoping you guys can help. We’re building a small 12x12 cabin on our land. So far we’ve started digging three footers and for all three, we’re hitting what feels like rock 2 to 3 feet down. I’ve looked up the soil survey for the property and it doesn’t say anything about bedrock being near the surface but that the fragipan is 14 to 26 inches down. Is it possible for a fragipan soil layer to feel like rock? I’ve struck it with my shovel and it hasn’t made a dent. We are in the mountains so not sure if maybe there’s some spots where bedrock pokes up. We can’t continue with the footers unless we know whether or not we hit bedrock or whether we need to break through the fragipan layer. Anyone had a similar problem??
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lburners
Member
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# Posted: 12 Oct 2020 07:57pm
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Get one of these suckers and give it a couple wacks.
https://www.harborfreight.com/lawn-garden/gardening-garden-tools/17-lb-digging-bar-wi th-tamper-93612.html
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mystereons
Member
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# Posted: 13 Oct 2020 10:04am
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Ok thanks for the idea! I have a pick axe I can try first.
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mystereons
Member
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# Posted: 13 Oct 2020 12:29pm
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Hi again, so after really trying to chip away at that layer, I think it’s the fragipan. It felt like rock because it’s a bunch of 2 inch rocks cemented together by hard soil. It’s going to be really tough to dig through it. I am considering just putting the footers on top of that layer because supposedly water doesn’t readily permeate fragipan. This is a small 12x12 unpermitted “shed†that I’ll be using as a work area during the day. So I know the footers wouldn’t be to code, but would it be stable and not easily subject to frost heave? Originally I was thinking of just putting it on blocks directly on the ground, so it seems like this would be a step up, but I could be wrong. Thoughts??
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jsahara24
Member
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# Posted: 13 Oct 2020 01:09pm
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You are correct that water doesn't generally percolate through a fragipan, and you end up with a perched water table above it. So assuming your frost depth is greater than the depth of the holes, you will likely see some movement as water will get stuck there and if it freezes it will heave your posts/piers.
Now considering what your building you may be willing to accept this and occasionally shim it as necessary, but that is a decision you will have to make.
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Brettny
Member
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# Posted: 13 Oct 2020 02:24pm
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If your not going below frost depth just put it on blocks. Esp for a 12x12 shed.
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mj1angier
Member
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# Posted: 14 Oct 2020 06:39pm
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I would just put it on blocks and use MH tie downs if worried about wind up lift. Makes it easier to level if it get uneven over time. This is what we did with our 12x20 shed cabin
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mystereons
Member
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# Posted: 15 Oct 2020 08:54am
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Hi, ok thanks everyone! I’m thinking about just putting it on blocks so we’ll see what happens.
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