barkeatr said:the entire foundation is a built up pressure treated grade beam, sitting on 12-18" fabric and crushed stone. stiffness for lateral strength comes off the sheathing and extensive timber frame type bracing. Ive done quite a few out buildings this way, the crushed stone minimizes/eliminates the freeze thaw movement. Expanding soils below push up on the crushed stone but the same movement does not get translated to the grade beam, it gets absorbed by the crushed stone. If frost movement does get translated to the building, the solid PT grade beam alows for easy shimming. Actually I have done a pole barn barn as you describe, only to have the frozen clay soils that we have here grab some of the posts on the side, and lift them and several of the posts settled because the solid CMU footing we put in must not have been large enough or it broke or the hole got overexcavated.. Of course the frost lift on the poles can be prevented with different techniques, but with our equipment on hand and a five foot frost line here, we decided to stay above it on this one. Its prolly just me but Iv never been able to get poles in the ground with out a small degree of skew or other issues...all of which are normal with barn accuracy tolerance but certainly are about the same tolerances that might be applied if frost movement gets to my building. With all this said, its a compromise, but with the issues surrounding other "low" cost foundations and the success of others I have done this way, we find the risks acceptable. thansk for your comments and good luck
barkeatr said:the entire foundation is a built up pressure treated grade beam, sitting on 12-18" fabric and crushed stone. stiffness for lateral strength comes off the sheathing and extensive timber frame type bracing. Ive done quite a few out buildings this way, the crushed stone minimizes/eliminates the freeze thaw movement. Expanding soils below push up on the crushed stone but the same movement does not get translated to the grade beam, it gets absorbed by the crushed stone. If frost movement does get translated to the building, the solid PT grade beam alows for easy shimming. Actually I have done a pole barn barn as you describe, only to have the frozen clay soils that we have here grab some of the posts on the side, and lift them and several of the posts settled because the solid CMU footing we put in must not have been large enough or it broke or the hole got overexcavated.. Of course the frost lift on the poles can be prevented with different techniques, but with our equipment on hand and a five foot frost line here, we decided to stay above it on this one. Its prolly just me but Iv never been able to get poles in the ground with out a small degree of skew or other issues...all of which are normal with barn accuracy tolerance but certainly are about the same tolerances that might be applied if frost movement gets to my building. With all this said, its a compromise, but with the issues surrounding other "low" cost foundations and the success of others I have done this way, we find the risks acceptable. thansk for your comments and good luck
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