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NullQwerty9
join:2008-12-18
united state

NullQwerty9

Member

Ok To Use Stone Dust For Fence Posts?

Hey folks,

I'm putting in a privacy vinyl fence 6' tall (5' + 1' topper). I've dug my holes 3' deep, 1' wide. I had been planning to use concrete to set the posts in place but I've heard about some people using Stone Dust instead and tamping it down in 1" intervals. The idea being that if your ground moves causing the fence to move, with concrete, getting it back to where it should be can be a huge problem. But with stone dust it will be much easier.

Has anyone used Stone Dust or heard of success or failures?

Note: This is for Massachusetts.

Thanks

rockotman
...Blown On The Steel Breeze
Premium Member
join:2000-08-06
DSotM

rockotman

Premium Member

One of the advantages of using concrete, being as you are in an area that does get cold weather part of the year, is that the concrete will go a long way toward preventing "frost heave" of the posts during freeze thaw cycles in early and late winter.

If the posts will be sunk in to a depth of 3 feet, that will also go a long way toward preventing frost heave, with or without concrete (assuming that your winters are about the same as here in southwest PA).

That being said, stone dust should work fine to hold the posts in place, and will provide an "easy" (well, I don't know about that - stone dust is heavy, sets pretty hard, and can be a bear to work with , but definitely easier than messing with a concrete-set post) way to correct a fence that goes crooked due to ground movement. The odds are, that if you use stone dust, you may end up having to repair the fence after several seasons of freeze/thaw. With concrete, the time between repairs will likely be extended. Like to maybe 25 years for concrete instead of 15 years for stone dust. The key word is "may". You may want to seek the opinion of some local fencing contractors familiar with the vagrancies of the soil in your area. Rocky/sandy soil is less likely to heave than silty or clay-laden soil, because rocky/sandy soil drains water better.

One more thing to consider... as all the old farmers around here will tell you, set fence posts during a waning moon (between a full moon and the last quarter) and the posts will not work themselves out of the ground.
NullQwerty9
join:2008-12-18
united state

NullQwerty9

Member

We definitely get some cold winters out here and freeze thaw/heave is an issue. Having said that, getting 15 years out of Stone Dust but being able to correct it fairly easy (in comparison) versus 25 years out of concrete, but being very difficult to correct seems like a no-brainer to me. Seems like Stone Dust is the way to go.

There is clay in the soil, but it tended to be the final 6"-1' at the bottom of the hole.

I've got 230 linear feet of fencing I'm putting in, and what gets me nervous is when I drive around and look at fencing, 80% of the fences are crooked and screwed up from ground movement. So, being able to fix it would be great. Although, I wouldn't want to have to fix it every 3 years either. I'd want at least 10+ years out of it.

Thanks for the reply!

rockotman
...Blown On The Steel Breeze
Premium Member
join:2000-08-06
DSotM

rockotman

Premium Member

The deeper the hole, the less likely a frost heave issue.

Around here, the rule of thumb is 32" will prevent frost heave, and that is using just the existing soil to back-fill.

I have split rail fence that was installed on this property over 25 years ago, and there is very little evidence of movement due to frost over the years. The bigger problem with some of my fencing (and we're talking nearly a linear mile of fencing) is that some of the posts have started to rot from age. I put in an additional 350 feet of new fence last year, and even after an extremely nasty, wet, winter, I see no evidence of movement. Granted, this is only split rail, so any movement is a lot less noticeable, but nonetheless, I see no evidence of movement. The only posts that I used cement on were the ones that I hung pasture gates on, and that was mainly because the gates present a fairly heavy cantelevered load on those posts.
Unxchay
join:2003-10-14
Milwaukee, WI

Unxchay to NullQwerty9

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to NullQwerty9
Frost depth here in WI is approx. 42" so we typically specify all footings down to 48" min. depth. As stated before, the deeper you go, the less likely you will have frost heave. You could also consider digging bell-shaped pits, where the bottom of the pit is slightly wider than the top. This is a pain to do but works quite well to reduce (or eliminate) heaving.

Between concrete and stone dust, I would choose concrete. In combination with a deep pit, that should provide you the most stability. Seems to me that using a flexible and lighter-weight backfill material will guaranty future fence movement.

Finally, a comment on your fence material. I have seen a lot of vinyl fencing fail in short order due to material strength, not installation issues. Are your top & bottom rails made of wood or vinyl? If the latter, they may start to sag after a year or two and get a noticeable 'wave' effect along the line. With a 'good neighbor' style fence topper this might be more pronounced. Something to consider.

Good luck!
TOM
NullQwerty9
join:2008-12-18
united state

NullQwerty9

Member

The material is vinyl but this is some strong stuff. Thick and also, the bottom rails are lined with thick strong aluminum beams, so sagging shouldn't ever become an issue. I've got some 8' sections as well, and with those all 3 rails and lined with the metal (note: with the 8' sections I'm going 4' deep).

I agree that concrete is stronger. My concern is that if it does move I won't be able to fix it. If Stone Dust is 85% as good at preventing movement, I think it would be better to go that way so that I can fix it if it happens. But there is very little info out there I can refer to so that I can find out some stats like "80% of Fences with Stone Dust move within 5 years" or the opposite that they don't move. I can't find much with people complaining about or much saying that it's great. It's just not that commonly used it seems. That fact alone is a concern, but that's why I'm here...to solicit feedback from those who have used it or seen it used.

Thanks for the help!

DataDoc
My avatar looks like me, if I was 2D.
Premium Member
join:2000-05-14
Hedgesville, WV

DataDoc to NullQwerty9

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You might want to read this:
»diy.stackexchange.com/qu ··· concrete

cdru
Go Colts
MVM
join:2003-05-14
Fort Wayne, IN

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MVM

to NullQwerty9
Frost line for Massachusetts is ~4'. That would be the minimum depth I would go no matter what you were using. I've always set posts by digging hole with a slight bell shape, plumbing fence post, and dumping in a 80# bag of concrete dry. Tamp every 6" or so. Then water. Come back next day and put up the fence and cover with dirt.
spud3
join:2007-03-24
Constantine, MI

spud3 to NullQwerty9

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When Not To Use Stone Dust

By Steve Pirie (Sales, Plymouth Quarries)
»www.plymouthquarries.com ··· Itemid=3

Actually, stone dust is more difficult to compact fully than crusher run, the aggregate base material mentioned earlier.
As for drainage, stone dust's powdery nature inhibits drainage. It absorbs moisture, holds on to it and drains very slowly. If freezing temperatures are present while the stone dust is still moist, the base will probably move (frost heaves). Crusher run, on the other hand, drains much better.
NullQwerty9
join:2008-12-18
united state

NullQwerty9

Member

Yeah, I'd be just as fine with Crusher Run. In fact, I've actually got some extra at my house.

My fear is that a number of these hole are going along the edge of the property line where the grade drops off significantly by 3-5'. To clarify, the fence is level, but the grade behind it (parallel to it) drops off. So, I can use concrete which is stronger, but being that the grade causes the soil to be softer and have less backing, I may be more prone to movement regardless of what I use, and if it moves, will I be able to fix it if it's concrete. Or I can use Crusher Run and be able to fix it if it does move. The unknown is how effective is Crusher Run at preventing movement compared to concrete? If it's 20% as effective, no way would I do it. If it's 85% as effective, then it's probably worth it.

Any other insights?

cdru
Go Colts
MVM
join:2003-05-14
Fort Wayne, IN

cdru

MVM

So you use crusher run. Several years later the fence post has shifted. It's now no longer plumb, or it's started to heave. How are you going to easily fix it? Anything besides completely resetting the post is just going to quickly shift again. Pulling the post, you now have a hole filled with crushed rock that's compacted to a semi-solid state that has to be removed. I don't see it that much easier then just using concrete.

You need to dig down 4' to prevent frost heave, so the grade sloping 3-5' I don't think will be a problem unless that slope is nearly vertical. You aren't pouring a piling, concrete or crushed stone, you only are going to have ~2 feet or so of the post encased which should have enough soil around it for support.
NullQwerty9
join:2008-12-18
united state

NullQwerty9

Member

Yeah, I'm not debating that concrete will be stronger. I know it will be...I'm just asking how much stronger. 3x stronger I use it. 25% stronger I won't.

Crusher Run can definitely be reset a lot easier. A 6' pry bar easily breaks it apart when compacted. I'd be able to dig it out and reset it with much less effort than 160-200 lbs of concrete solidified to the post.

cdru
Go Colts
MVM
join:2003-05-14
Fort Wayne, IN

cdru

MVM

said by NullQwerty9:

I'd be able to dig it out and reset it with much less effort than 160-200 lbs of concrete solidified to the post.

Why are you using 160-200 lbs of concrete on a post? 1 80lb bag has always been more than enough for every post I've set.

IMHO, either would work. I would just use concrete.
NullQwerty9
join:2008-12-18
united state

NullQwerty9

Member

Sorry, should of said 120-160 lbs. Manufacturers specs say 1 and 1/2 bags for the 6' tall sections and 2 bags for the 8'.

Thanks for all your input!

I ran a test. Took a 5 gallon bucket, put a few inches of crusher run in it, compacted it, then put in a wooden stake. Filled the remainder up with crusher run compacted along the way. In the end, it definitely was very solid. Pushing and pulling the stake caused the bucket to tip, rather than the stake to push into the crusher run, which is good. It was heavy which was also good (I'd guess between 30 and 50 lbs). There was about 1/32" of movement/play allowed, but that would be fine.

I might try to post to one more forum and see if I can find some people that have tried it and had luck with it, or failure.

Thanks everyone