ᐅ Excavating a Basement Foundation: Can It Be Done Independently as a Non-Professional?

Hello everyone,

My husband and I are building a house on our own. That means we are having it built, but we are doing the planning ourselves, handling all the paperwork, sourcing the materials, hiring the contractors, etc.
The construction financing is secured, the architectural plans are finished, the plot has been purchased, and the surveyor has been hired.

We have a construction company that will take care of the shell and the interior finishing. They are also building the basement, but they won’t be excavating the hole for the basement.

Our plot is roughly half a meter below street level. (The surveyor will surely give me more precise information on that.) The purchase contract for the plot states that we have to raise the land to street level.
So I’m quite certain that the soil we excavate for the basement won’t have to be disposed of at high cost but can be distributed on our plot.

So it’s “just” about digging a hole approximately 2.5 m (8 feet) deep.

Is something like this manageable to do with a mini excavator on your own? Has anyone had experience with this? How long does it typically take? Is there a high risk of causing damage? I understand that the walls need to be supported somehow. Would the basic support approach I imagine as a layperson be enough, or would you need to rent (besides the mini excavator, of course) heavy equipment, construction fencing, and professional shoring systems, which would seriously reduce any financial savings?

Are the information from the soil report and the surveyor sufficient to anticipate all possible issues (such as hidden water veins, etc.) in advance?

I imagine it to be relatively straightforward: stake out the footprint, start the digger, remove the soil, level the ground, done.
But I have learned that I often tend to think things are simpler than they actually are.

So I would appreciate your assessment:
Is it quite feasible (without risking your life) for a layperson, with the help of instructions and under optimal soil conditions, to dig an excavation of this size (11 x 11 m (36 x 36 ft) x approx. 2.5 m (8 ft))?
Or is it better not to try it, because the risk of problems at the end is greater than the potential cost savings?

You are definitely underestimating the project.
Just the idea of using a mini excavator... you want to dig down 2.5 meters (8 feet). How are you going to get the excavator out of the hole afterward?
You won’t be able to reach that depth from above. And digging out almost 300 cubic meters (almost 10,600 cubic feet) of soil... you’ll be busy for several days if you’re talking about a small 2-ton excavator. The bucket will need to be filled many times.
You won’t get far enough down from above. Not to mention the risk of the excavator slipping in with you.

Depending on the weather, shoring will be needed to varying degrees... if it rains heavily, you wouldn’t be the first person to find the excavation filled back in the next morning.

I’m not a professional, this is just my technical intuition, if you can call it that. I’m happy to be proven wrong, but I can’t imagine this will work. Although... my neighbors once built basements without excavators.

I have very little technical knowledge, but my logical mind tells me otherwise. Isn’t it true that the leveling process already sets the exact height or depth, meaning you need to dig carefully down to the centimeter (inch)? And then the surveyor provides a precise measurement showing exactly where the excavation should take place. Or not? No idea... I could imagine doing the excavation for a terrace myself if I had a few days to do it.

I can only agree with the previous speakers here. I am also not an expert in this field, but for the reasons mentioned above, you should assign this work to professionals.

bibliophilia schrieb:

Are the information from the soil report and the surveyor sufficient to anticipate all eventualities (hidden water veins, etc.)?

As far as I know, a soil report only takes samples at specific points (drilled boreholes, etc.). Therefore, there could still be water veins within the building plot that might be interrupted or destroyed during excavation. If these interrupted water veins are not redirected, the pit could fill with water – this is what I have been told about this.

By the way, I find it very impressive and ambitious that you want to handle the planning, finding/hiring companies, and sourcing materials completely on your own. Wow. I wouldn’t dare. What if a material isn’t delivered on time or an element is forgotten? Then the entire construction could be delayed for days or weeks. Respect for your courage.

Alright, I realize that I can’t or shouldn’t do this myself. The surveyor also strongly advised against it. It would have been too good to be true. I would just really like to handle it myself, but I have to accept that there are things better left to people who know what they’re doing.