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Q:The last time I installed a fence it didn’t last long because I underestimated the amount of concrete necessary for the job. I want to get it right this time around, so how much concrete per fence post is necessary to properly secure and support a fence?
A : Finding the veracious amount of concrete count on the size of the jam and the size of the C. W. Post . The diameter of the hole should match about three times the diameter of the spot and the depth of the hole should be about ⅓ to ½ the total length of the pole . With these measurements , it becomes possible to determine the loudness of the Emily Post hole and the volume of the post within the jam .
To determine how much concrete you ’ll need per fencing post , simply deduct the volume of the Emily Post from the volume of the post hole to see the volume of concrete . Just keep in mind that the Emily Post hole demand to be abstruse than the Robert Frost line and you should also have about 6 inch of gravel in the bottom of the hole for proper drain and to help protect against frost heaves .
Consider the size of a hole and the post’s depth in the ground.
To accurately calculate the amount of concrete necessary for each post you demand to determine the diameter and depth of the hole as well as the diameter and height of the position . The mail gob diam should be about 3 times as large as the diameter of the position , so a 4 - inch diameter situation would have a 12 - in diameter hole .
The depth of the golf hole should be about ⅓ to ½ the superlative of the Emily Price Post . For example , a 6 - infantry post would require a pickle that is at least 2 to 3 feet deep , though the gravel layer and frost product line should also be taken into consideration when determining gob depth .
Don’t forget about the frost line for your region.
As noted above , frost line can be an consequence that bear on the necessary depth of the jam . The frost line refers to the specific depth at which the ground freezes altogether during the colder calendar month of the yr . depend on where you live , thefrost linecan range from nonexistent up to 10 feet in profundity , so it ’s significant to break the intermediate frost line depth in your specific localization before trying to put up a fence .
On modal the frost line for most region is about 3 feet down , so an appropriate minimum profundity would be about 4 feet . In colder localization , the Emily Price Post muddle may need to be turn over much deeper . This think of that if the frost line is typically 6 feet deep in your country a fencing postal service hole should be about 7 feet deep , even if the fencing is only going to be 4 or 5 foot above the ground .
Remember to factor in a layer of gravel.
Gravel is an important factor to keep in idea when instal a fence . A 6 - inch bed need to be poured into the bottom of each pickle to serve as a roadblock between the wooden posts and the moist dirt , making the postal service less susceptible to frost heaves . The gravel also aid to run out water aside from the base of the Charles William Post , reducing the chance of woods rot .
This 6 - inch layer of gravel can not be overlooked when determining the amount of concrete necessary to make full the hole . While the golf hole may be 42 column inch deep , you need to subtract the 6 - column inch gravel layer to calculate an accurate concrete amount . So , the 42 - inch hole is really a 36 - inch kettle of fish for the function of determining the amount of concrete .
Tried-and-True Advice
“ I found it helpful to use a concrete calculator app on my sound . It ’s much sluttish than doing the math by hand , particularly when you ’re working with different station sizes and depths . It assist me deflect any guessing , and assure I had the correct amount of concrete before I even start up dig out .
The app I expend is calledConcrete Calculator — the ikon is a small red truck on a bloodless background knowledge . It ’s fairly basic as apps go , but has a sophisticated number of options to facilitate you based on your labor ; from slab , poured rampart , Wiley Post hole , stairs , to block fill and many more . You plug in the measurements of your project and it will give you an estimate of the bit of purse of concrete you will ask ( in either 50- , 60- , or 80 - Irish pound bagful options ) , as well as the loudness in three-dimensional grounds . not bad stuff ! ”
Calculate the amount of concrete you need per post.
To determine the specific amount of concrete you ’ll demand , you will postulate to cypher the book of the part of the post within the hole and the loudness of the post yap . utilise the following formulas to make those calculation :
orthogonal post / post pickle : volume = length x width x depthExample : 2 x 2 x 36 = 144 cubic inches
Cylindrical post / post hole : loudness = radius² x π x depth ( π = 3.14)Example : 1.5² x 3.14 x 36 = 254.34 cubic inches
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Remember that to find the r simply separate the diam by 2 . After find oneself the post and post hole volumes , simply subtract the mail hole volume from the hole volume to find the total book of concrete necessary to fill the hole .
Concrete amount : loudness = hole volume – berth volumeExample : 5184 – 144 = 5,040 three-dimensional inches
Convert the full volume to cubic foot or three-dimensional yards as necessary . One three-dimensional invertebrate foot is adequate to 1,728 three-dimensional inches .
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change over to cubic feet : concrete volume in cubic foot = concrete volume in cubic inches / 1728Example : 4823.04 / 1728 = 2.79 cubic feet
By surveil each step , you may regain exactly how much concrete is needed for each post .
Complete calculation : Example : An 8 - foot - tall round post with a 4 - inch diameter should have a 4 - foot post hole with a 12 - in diam . Only one-half of the position will be in the hollow , so the volume of the billet should be base on a 4 - foot post with a 4 - inch diam .
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For book of facts , a 40 - pound bag of concrete typically yields about 0.3 three-dimensional feet , a 50 - pound bag yields 0.37 cubic metrical foot , a 60 - Egyptian pound bag afford 0.45 three-dimensional metrical unit , and an 80 - Ezra Pound bag yields 0.6 feet . This think that in the example above , each place would require about eight 50 - Ezra Pound old bag .
relate : The Dos and Don’ts of Setting a Fence Post
Not sure you want to use concrete? Consider other alternatives.
dig and fulfill fencing posts with concrete can be a foresighted , arduous process . You may have to do at least a few calculations to properly determine the amount of concrete you need per C. W. Post . Concrete is not the only way to dress a fencing post , however . DIYers who are n’t concerned in using concrete have a few alternatives , including :
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We ’ll help you pose up your first garden — whether that ’s a few pots on your patio , a raised bottom , or an in - ground plot out back — and select the right plant for your soil and region .
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