I might have mentioned once or twice on this blog that having a clay soil causes a few complications when building. A few months ago we dug some holes where we wanted to plant the concrete footings on which our container house would sit. However we didn’t have the the final specs from the structural engineer and were unable to finish the work. We are glad we did dig the holes though, because it gave us a good opportunity to examine the soil type; all information useful for us and the structural engineer. Now we have received the final specs for the shipping container house footings from the structural engineer, John Moll, so can continue the work.
So, that means we could carry on with digging the footing holes to the correct specifications so that they will be safe and long-lasting.
Changes Required For Shipping Container House Footings
John advised us to dig out the soil past the clay. When clay soil is wet it becomes squidgy. Several tonnes of house sitting on a layer of clay would sink. It’s kind of like standing still on the beach with the waves coming over your feet. You slowly begin to sink.
That means we had to dig much deeper holes to get to the bottom of the clay layer. This time we decided not to do it by hand. We used the TLB that we hired.
I thought it was quite interesting that the TLB used the loader on the front to level the ground and the backhoe bucket on the back to dig the holes. You’ll also notice that the TLB uses the loader to stabilize itself while it digs, along with the stabilizer arms on the side. Very clever design!
The way the TLB scoops out the soil means that the holes are now much wider than we need, but the point was to get under the clay. This we have accomplished with very little effort, thanks to the heavy machinery.
The next thing to do was to square out the bottom of the holes exactly where the footings are going. That we have to do by hand, but this is under the clay so it’s a lot easier than when we were digging the hard sun-baked clay last year.
The squared out holes look like this.
At this point, John Moll, our structural engineer, came to check up on our progress. He’s happy with our hard work and we’re able to proceed.
Our next step is to back-fill the holes with something much more stable than clay (G5 & G7). Then we can finally start casting the concrete.