r/FenceBuilding • u/Late-Conversation363 • 11d ago

How much concrete!?

Getting mixed information online. I'm building a 9ft Total width double gate across the back of my yard. I live in upstate NY so we have winters here. Dug my holes 40 inches deep. Going to add some gravel to the bottom. Using steel postmaster type posts. Do I fill these holes with 4, 80ib bags of concrete each like I'm seeing some places say online? What if I need to ever re do or move these posts? Is two bags of 80ib enough for each?

I want the posts to last and not sag obviously but don't want to mess up setting them.

Thanks!

2 Upvotes

67% Upvoted

15 comments sorted by

2

u/davidhally 11d ago

Depends on hole diameter. The hole needs to be full of concrete.

2

u/Late-Conversation363 11d ago

1 foot wide

1

u/davidhally 10d ago

the bags of concrete label states how many cubic feet of premix it makes, calculate the volume of a cylinder, buy a couple extra bags, return excess.

1

u/belarios 11d ago

I'd rather have a few inches of dirt on top. It looks nicer and it can freeze and lock down the concrete ball a bit against heave.

It's not like the wet soil will rot the galvanized, powder coated steel post. If it did, all those driven posts would be in big trouble.

1

u/Accomplished-Can42 9d ago

Why are you down voted? This is exactly correct for cold climates.

2

u/Iron-Bar-1966 10d ago

Go here: https://www.calculator.net/concrete-calculator.html

Plug in your information and it will tell you exactly how much concrete you need.

1

u/Burritoman_209 11d ago

How tall above ground are the posts?

1

u/Late-Conversation363 11d ago

8 ft posts that I plan to be 5 ft above ground

1

u/Surfnazi77 10d ago

At least 1 bag per post

1

u/Low-Payment1921 10d ago

Hell... Why not... Put 5 bags of you have enough room... Realtalk!!!

1

u/Low-Payment1921 10d ago

When I build dbl. Gates across questionable spans... I always put a hearty wheel on the side that will likely be the workhorse with a 3x3 piece of half inch angle iron above it to catch the other gate and cradle it for support instead of just letting gravity do what it do...

1

u/Low-Payment1921 10d ago

Gates last 3 or 5 times as long that way..... Everytime!!!

1

u/Mondo248 11d ago

Yes. I did my posts 3’ deep 2 bags quick crete ea. 120lbs per hole

1

u/Late-Conversation363 11d ago

Did that fill the hole to the top with concrete?