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256 Posts

.4 cubic yards/10.8 cubic feet per post-hole

1.6 cubic yards/43.2 cubic feet for 4 total post-holes

66 80lb. bags of concrete

I have read there is about 2/3 of a cubic foot per 80lb. bag. Is this an accurate estimate?

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Joined

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256 Posts

.4 cubic yards/10.8 cubic feet per post-hole

1.6 cubic yards/43.2 cubic feet for 4 total post-holes

66 80lb. bags of concrete

I have read there is about 2/3 of a cubic foot per 80lb. bag. Is this an accurate estimate?

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4,113 Posts

I lived in SE VA and when people described ocean front was highly variable depending on the timing since everything was considered to eventually be ocean front.

The elevations required are dictated the possible storm surge (worse than a hurricane wind).

Considering the depth required in the poor soil and the height above grade, the requirements seem to make sense.

People in the surge path of Katrina wish they had to protection of some decent local codes and code enforcement.

Dick

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2,915 Posts

Sometimes it can be easy to misunderstand construction. This is typically how they are done in my area in Massachusetts.

depth of footing is typically based upon several issues:

1. frost protection depth required by code

2. depth to undisturbed virgin soil

3. engineered structural fill in lieu of deep footings

4. closeness to existing dwelling (see #2)

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2,585 Posts

Not to be that guy, but there is an error in your volume.My concrete calculations came to:

.4 cubic yards/10.8 cubic feet per post-hole

1.6 cubic yards/43.2 cubic feet for 4 total post-holes

66 80lb. bags of concrete

I have read there is about 2/3 of a cubic foot per 80lb. bag. Is this an accurate estimate?

V=(î)r²(L)

V=3.14 (1²) (4)

V=12.56 ft³ per hole

Multiply your volume (in ft³) by 1.5 to get the number of 80 pound bags.

I get 76 bags.

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2,885 Posts

Ok That guy, you forgot to subtract the volume taken by the post itself.Not to be that guy, but there is an error in your volume.

V=(î)r²(L)

V=3.14 (1²) (4)

V=12.56 ft³ per hole

Multiply your volume (in ft³) by 1.5 to get the number of 80 pound bags.

I get 76 bags.

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4,113 Posts

I assume they do not require concrete in the above grade, since you are talking about wood posts.

Dick

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2,585 Posts

Thank you Jack for pointing out my mistake. I over-looked the fact that the 8x8 are piers, not posts anchored to the concrete.Ok That guy, you forgot to subtract the volume taken by the post itself.

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256 Posts

Would it be possible to pour and mix the concrete in the hole???

66 bags of pre-mix @ about $4.00 per bag, plus delivery = About $300-$350.

2 yards of ready mix concrete delivered to site: 2 yards @ $120 a yard = $240

cartage/partial load charge of $50-100

Total for ready mix = $290-$340

If you calculate in incidentals like chiropractor visits and such, I think it's an easy decision..........:thumbsup:

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655 Posts

We rarely use bag mix anymore, even when it's "cheaper" it's not, I'd rather be done pouring in 30 mins than have 1 or 2 guys mixing all day long, plus they're worn out afterwards. Call in a truck.

66 bags of pre-mix @ about $4.00 per bag, plus delivery = About $300-$350.

2 yards of ready mix concrete delivered to site: 2 yards @ $120 a yard = $240

cartage/partial load charge of $50-100

Total for ready mix = $290-$340

If you calculate in incidentals like chiropractor visits and such, I think it's an easy decision..........:thumbsup:

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