Post hole borer - size of auger

I am hiring a post hole borer to put a number of 75x75 post in. I have the choice of 150mm or 200mm auger. Which is more suitable for this job please?

Asked by Natalie on 27th Apr 2021
Expert Trade Answers
"200mm as it will give you room to position post correctly and space for postmix to secure post in place!"
Answered on 27th Apr 2021 - Member since May 2019 - report
For 75/75 post better choice for 200mm may use more postcrete but you get a better resistance as will depend on the height of the fence as a general rule is when setting a fence post into the ground, the height required above the ground should be divided by 3 and this figure is the hole depth required. The width of the post hole should be 3 times the width of diameter of the post.

For example, if you are erecting a 6 foot high fence using 4 inch fence posts, the posts need to be 6 feet above the ground. 6 divided by 3 is 2, therefore the depth of the hole required is 2 feet.
Answered on 27th Apr 2021 - Member since Mar 2021 - report
"The 200 borer would be my preference has it would
Give the post more strength in the ground .Then use post mix
Good luck Phil."
Answered on 27th Apr 2021 - Member since Jun 2018 - report
"200mm would be preferable, in case posts are slightly bigger."
Answered on 27th Apr 2021 - Member since Jan 2020 - report
"I would go with the 150mm as you dont want the hole to be too wide"
Answered on 27th Apr 2021 - Member since Nov 2020 - report
"You need a 2ft deep hole by 150mm in width, the width only needs to be the double of the post bare in mind that once you have got your postcrete in place there is still chance of movement, you are only needing to allow enough to put your post in and postcrete to hold it in place."
Answered on 1st May 2021 - Member since Feb 2020 - report
"150mm will do the job just fine with plenty of room for backfill"
Answered on 14th Dec 2021 - Member since Mar 2019 - report
"I would personally go for 200mm that will give more room for concrete/course mix (the more the better)."
Answered on 22nd Aug 2021 - Member since Jun 2021 - report
"It depends on a number of things, the size of the post, the height of poles, the material the post is made from, you have to consider all these things. But generally, if you have a6ft post made from wood, you want to put it near enough to a third in the ground and the size of the auger in my experience should be double the size of the post, so for your post size, the hole size should be 150in.
There you have it."
Answered on 10th Aug 2021 - Member since Jul 2021 - report
"There isn't really that much difference, I guess it depends how much cement you want in the hole. If you are a novice I'd go for the 150mm as it will be easier to keep the post in position when your putting the postcrete in."
Answered on 24th Jun 2021 - Member since Apr 2021 - report
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