We are going to be building a new home and are in process of getting our figures together for our construction loan. We would like to get bids on building the house pad but everytime I talk to someone they want to know how many tons of dirt I need but nobody is ever able to convert the figures to tons. We need a house pad that is 7000 sq. ft. and we need it built up about 30 inches. I understand that with the compaction rate we will need to add about 1/3 more onto the total amount of dirt needed. Can any of you math wizards out there help? Thanks!
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Re: building a house pad
First convert everything to the same base unit.
30 inches / 12 = 2.5 feet
Now calculate the volume needed.
7000 square feet * 2.5 feet = 17500 cubic feet
So thats how much dirt you need. The trouble is that not all dirt weighs the same, so the next part would just be an approximation.
According to Reade:
Earth, loam, dry, excavated  78 pounds/cubic foot
Earth, moist, excavated  90 pounds/cubic foot
Earth, wet, excavated  100 pounds/cubic foot
Earth, dense  125 pounds/cubic foot
and the list goes on.....
I will use the dry earth as the example.
17500 cubic feet * 78 pounds/cubic foot = 1365000 pounds
Now to tons.
1365000 pounds / 2000 = 682.5 tons
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Re: building a house pad
I am in a similar predicament as the previous post. I am building a house pad that is 2100 Sq ft. My issue is that there is a 4ft difference from east to west that I will have to level. Using your caluclations (again using dry earth as the example) I came up with 327.6 tons of earth required. Is that right?
2100 x 4ft = 8400 cb feet
8400 x 78  655200
655200 / 2000 = 327.6
Please advise...
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Re: building a house pad
That would be correct for 4 foot of earth over 2100 square feet.
Though it sounds like in your situation you have 4 foot on one side and less on the other. Similar to a trapezoid shape like this one (but laying on its side).
Lets say you had to fill 2100 square feet from 4 feet deep on one side down to 1 foot deep on the other side. In that case you would need about 5290 cubic feet of earth, as compared to 8400 cubic feet if it was 4 foot deep over the entire area.
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