ᐅ Amount of Cement Needed for Privacy Fence Posts

Hello,

how much cement do I need for my 25 holes for a 2 m (6.5 ft) high privacy fence? The drilled holes currently have a diameter of about 20 cm (8 inches) and a depth of about 45 cm (18 inches). That is a volume of approximately 0.014 cubic meters (0.5 cubic feet).

According to the hardware store, I need about 50 kg (110 lbs) of cement per hole, so around 30 bags in total.

That seems like a lot to me. Is that correct?

Thanks and best regards,

downundaman

The cement bag indicates 20 kg per square meter (sqm) per centimeter (cm) of layer thickness. The hole measures 0.1 x 0.1 sqm × pi = 0.03 sqm. This means that at about 33 cm (13 inches) height, I would have one square meter. The hole is approximately 1.5 times higher, so 20 kg × 1.5 = 30 kg.

Still a lot, but it sounds more realistic, right?

I always calculate with 2kg per liter. The number of liters is the product of height times width times depth, each measured in decimeters.
So here approximately 2 x 2 x 4.5 = 18L, which equals 36kg. Slightly less because it’s a circle, not a square (minus 20%), so it’s about 30kg.

Eh, a hole with a diameter of 20cm (8 inches)? What is the purpose of that?

Not only does the hole diameter make me suspicious, but also the depth for a 2 meter (6.5 foot) high fence.

In my opinion, the foundations are clearly too small; wind pressure should not be underestimated.

Diameter 25 cm (10 inches)
Depth 80 cm (31 inches) (frost protection)

Concrete / sand mixture 1:3 (better safe than sorry)

I have founded about 50 posts this way, and all are still holding.

During the last storm, several fences were knocked down in our construction area...

Good luck

Skippy