ᐅ Earth auger for pier foundations – what diameter is recommended?

We want to create pier foundations for a log fence, a chain-link fence, and a greenhouse. However, I don’t want to dig all of them out by hand with a spade, and renting a motor-driven earth auger is too expensive. Therefore, I’m considering using a manual auger. What size would be sufficient here? Is a 20cm (8 inches) diameter enough? There is a version from Fiskars that I’m somewhat interested in. Otherwise, I also have 25cm (10 inches) and 30cm (12 inches) augers from other manufacturers in my shopping cart. What do you recommend?

Also, should I insert PVC pipes into the holes, or is it better to pour the concrete directly into the soil?

Hi,

a 20cm (8 inch) auger is more than sufficient for posts, and it should also be enough for the footing holes. However, I would advise against using a manual auger, as you will quickly lose interest unless you have pure sandy soil. It’s not enjoyable work, so it’s better to buy an affordable motorized one, which usually comes with two or three different drill bits.

Pouring concrete directly into the hole provides more stability than using a sleeve in your case.

Thanks for the reply!
That sounds good. I have always read about 30x30 or 40x40 foundations, but I guess those are more for carports, pergolas, and other large structures?
However, once we have the cost estimates, it’s quite possible we’ll prefer to do it ourselves...

I’m still undecided about the powered auger. On one hand, the Fiskars manual earth auger has excellent reviews, but on the other, I’m not a fan of those noisy, maintenance-intensive petrol engines. Are there good electric versions available? Or are the petrol ones better?

Hello Changeling

Try googling "Lochspaten." I find it better than a hand auger.

Steven

I have looked into it, but I am more convinced by the concept of the earth auger. The hole shovels seem cumbersome, and I imagine that beyond a certain depth, it becomes difficult to work with them effectively, especially in tougher soils.

Why do you prefer the hole shovel?

An electric version is new to me, but it makes sense since these tools are mostly used in agriculture or landscaping, where electricity is not always available.

What kind of maintenance would you need for your 50 holes? Just add gasoline and you’re good to go. Buy a device for €250 (about $270) and then resell it on classifieds for €180 (about $195), and you’re done.