Let me start with the fact that I am brand new to building. I built a chicken coop and that's it. This summer I am building a 16x20 cabin on my land in Willow. 2 weeks ago I went and dug 9 holes with a hydraulic digger about 4' down. I used 4'x8" sonotubes and filled with concrete. I placed a J bolt in each one to attach a bracket for holding the beams. So 3 rows of 3 tubes each, Then laying a 20' 4x12 treated beam across each one. Creating a three 20' horizontal beams spaced 8 feet apart. So I created a platform to lay my subfloor on. I plan to attach the subfloor to the beams with thread rods later on.
THE PROBLEM. After I poured the tubes I realized I should have made the footings wider by adding bigfoot footings or at least belling out the bottoms and lifting the tube after the pour. This would prevent jacking and also provide more weight distribution...Well too bad I didn't think of that when I poured them. SO they are 8" wide and have 42" below ground...leaving the top 6 inches or so above grade. My Question is what to do now!? I have sandy soil with a touch of clay/silt...hard to tell, but mostly sand below the 12 inch line. Well drained area...sits up higher than everything around it. Large birch and white spruce trees present. No water pooled up in the holes even after that rain we just had.
I have been told by a few local builders that "its no big deal...a cabin that size is fine on 8inch feet since I dug down so deep into undisturbed soil ...and unless its really wet/silty soil, frost-jacking would not be a problem either since I have good drainage."
I figure I can do one of a few things..ONE: get a bumper jack and remove all the tubes from the ground...discard and start again with bigfoot footings and rebar...wasting all my time and money previously invested and then buying it all and doing it again...not fun. TWO: add a 4-6 more piers to increase my load capacity and hope frost jacking isn't an issue. THREE: Add more piers WITH bigfoot and rebar to stop jacking and increase load capacity...HOWEVER...Ive heard that having some piers anchored and some not is MORE of a problem because they will settle and heave differently. FOUR: LEAVE IT ALONE and see what happens...They are on j bolts so settling is an easy fix...jack up the cabin, raise the bracket and set back down. Ive been told jacking isn't always a major problem...maybe the cabin will be a little unlevel but it should still hold for years to come??? Not sure..OPINIONS??? Should I face the fact that I blew it and spend the 1000 bucks to do it again...or is it good enough for a little fishing cabin in the woods... THANK YOU