# Help with Sonotube and Piers



## User02 (Sep 17, 2015)

I need to pour some 20 inch round concrete piers.. They need to go 60 inches into the ground and extend 48 inches above ground. Some of them only need to extend 24 inches above the ground.

All the video's I'm seeing on Youtube show folks extending the sonotube all the way to the bottom of the post hole.. Sometimes they use bases, sometimes they just put the form on the dirt bottom of the hole.

I have to pour 10 of these and that's a lot of sonotube.. $1000 dollars worth.. 

So I was wondering if there's a better way.. When I called my local concrete place, they said the sonotube does not need to extend all the way to the bottom of the hole.. Great! So I only need maybe a foot or so into the ground.. 

But how does one go about installing the sonotube into the hole in such a manner that allows the concrete to fill the hole and extend up into the tube without leaking around the bottom of the tube? 

Whenever we pour concrete around here, we're always worried about the concrete lifting up the forms and leaking out the bottom.. so we stake them down really good. But that's usually square stuff and the forms have a nice dirt base to seal the bottoms.

How is this done?


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## jlhaslip (Dec 31, 2009)

What I have done in the past for setting sonotubes is to build a box the size of the required footing and cover it in OSB, cut out a circle for the sonotube and secure the sonotube to the box with cleats on all 4 sides of the tube.
Build another frame of cleats for the top. Attach braces to the top frame for stabilizing and positioning of the sonotubes. 

Clear as mud?

*EDIT*

Picture attached


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## de-nagorg (Feb 23, 2014)

Most bakeries and cake shops, buy their frostings in 4 to 5 gallon plastic buckets.

I can buy the empty buckets from the local shops for $.50, (50 cents )each.

Cut the bottoms out and tape them together to make my tube forms, much cheaper than buying a sono-tube.

The bakeries are glad to get rid of these and make a little $ on them.

ED


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## Bondo (Dec 8, 2007)

> I need to pour some 20 inch round concrete piers.. They need to go 60 inches into the ground and extend 48 inches above ground. Some of them only need to extend 24 inches above the ground.


Ayuh,..... How are ya diggin' the holes in the ground,..??

If ya auger the holes at the diameter of the tubes, No they don't need to go to the bottom of the hole,....
If yer diggin' with a hoe, ya need full length tubes to act as forms, holdin' the back-fill out,...


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## User02 (Sep 17, 2015)

jlhaslip said:


> What I have done in the past for setting sonotubes is to build a box the size of the required footing and cover it in OSB, cut out a circle for the sonotube and secure the sonotube to the box with cleats on all 4 sides of the tube.
> Build another frame of cleats for the top. Attach braces to the top frame for stabilizing and positioning of the sonotubes.
> 
> Clear as mud?
> ...


The way I'm reading your diagram, your sonotube goes all the way to the bottom of the hole right? 

My holes have to be 60 inches deep.. The way the concrete store guy described it, I should be able to install the sonotube in such a way that only the part showing above grade is nice and round and smooth.. the concrete poured below the surface would be in contact with the ground soil.. Only the part above ground level, and maybe a foot below, would be in contact with the sonotube.

Did I miss read your drawing?


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## User02 (Sep 17, 2015)

Bondo said:


> Ayuh,..... How are ya diggin' the holes in the ground,..??
> 
> If ya auger the holes at the diameter of the tubes, No they don't need to go to the bottom of the hole,....
> If yer diggin' with a hoe, ya need full length tubes to act as forms, holdin' the back-fill out,...


We're going to use an auger to go the first 4 feet (as deep as the auger is made to go) and then we'll have to do the rest by hand.

My experience with augers is that the hole is never nice and clean and round.. Not even remotely close. 

jlhaslip suggested I use some plywood and cut a hole for the sonotube and anchor the tube to the plywood.. 

So I'm thinking the following:
Cut a piece of 3ft x 3ft plywood square.. Make hole in middle that tightly fits sonotube snuggly... Slide the sonotube through the hole about 12 inches and screw the sonotube to the plywood. 

After digging my hole, I would then use a shovel to dig out a 3ft x 3ft square of dirt around the hole to fit the plywood /sonotube combo and then place weights on top of the plywood to hold it in place.. 

See diagram.. 

Would that work?


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## jlhaslip (Dec 31, 2009)

Shopguy said:


> The way I'm reading your diagram, your sonotube goes all the way to the bottom of the hole right?
> 
> My holes have to be 60 inches deep.. The way the concrete store guy described it, I should be able to install the sonotube in such a way that only the part showing above grade is nice and round and smooth.. the concrete poured below the surface would be in contact with the ground soil.. Only the part above ground level, and maybe a foot below, would be in contact with the sonotube.
> 
> Did I miss read your drawing?


Nope. You read it correctly.
This approach is used when a Hoe has been used to dig a hole or a trench for the sonotubes. 
If you are going to auger them, use a cleat ring around the top and at grade level to secure the sonotube to and brace both of them in two directions so it doesn't move.


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## Bondo (Dec 8, 2007)

> We're going to use an auger to go the first 4 feet (as deep as the auger is made to go) and then we'll have to do the rest by hand.


Ayuh,.... They rent shaft extension shafts,.... 2' increments I believe,...

What diameter is the auger,..??

By just droppin' in sonotubes to the bottom, 'n fillin' 'em with concrete, ya use less concrete than just fillin' the hole,...
Back fill 'em before ya pour, 'n the friction with the back-fill holds 'em in-place,...


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## User02 (Sep 17, 2015)

Bondo said:


> Ayuh,.... They rent shaft extension shafts,.... 2' increments I believe,...
> 
> What diameter is the auger,..??
> 
> ...


Ya but those darn sonotubes are freaking expensive at 20" diameter... They're $100 each 20" x 12ft and I need to make 10 pillars of various lengths from

I have an unusual number of empty 55 gallon drums at my disposal.. 55 gallon drums have an inside diameter of 20.5 inches so I was thinking about using the 55 gallon drums under the ground and then attaching the sonotube to the top of them... They'd probably rust out and turn to dust in a decade or so. I could just chop off the top and bottom plates and use them just like a sonotube.


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## de-nagorg (Feb 23, 2014)

Your drums will work fine.

I have seen it done in the oil-field.

Good idea.

One point of caution , make sure that there is no hydro-carbons in the drums before hitting them with a torch to cut the ends off.

Saw a fool launch one 100 feet before , by not cleaning it out.


ED


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## User02 (Sep 17, 2015)

de-nagorg said:


> Your drums will work fine.
> 
> I have seen it done in the oil-field.
> 
> ...


LOL.. Ya I can imagine that. 

I'm an engineer and did some work for a food processing factory that takes bulk vegetable oils and repacks them in retail packaging.

They give me their empties.. one time use, very clean except for a bit of food grade oil inside. 

I cut them all the time with a plasma cutter. I get hundreds of them.. 

Thanks!


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## Bondo (Dec 8, 2007)

Ayuh,... The steel drums oughta work,....

My point above is that sono-tubes are cheaper than yards of concrete,...


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## MTN REMODEL LLC (Sep 11, 2010)

I'm guessing that if you are going that deep and that big, there are engineering consideraations involved.

If in snow/freezing country, your engineer may want smothwall (no wash out of open hole for frost lift) to the bottom.

If not, or your auger/soil drill clean smoth bore, and excess concrete cost for wash out is not excessive, I'd fill the hole with concrete and drop and x-post the sonotube above ground. Well x-posted, it won't go anywhere.

On 12" for decks , I do it all the time.

Do you need any rebar/caging in it... then you have some other considerations.


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## User02 (Sep 17, 2015)

MTN REMODEL LLC said:


> I'm guessing that if you are going that deep and that big, there are engineering consideraations involved.
> 
> If in snow/freezing country, your engineer may want smothwall (no wash out of open hole for frost lift) to the bottom.
> 
> ...


I don't know what wash out of open hole for frost lift means.. Our frost line is 42 inches, I'm going 60 down.. I can't imagine frost would have any effect. 

I will be installing rebar but it wasn't specified in the original engineered drawings from IronRidge. I'm probably going to go with 1/2" rebar and put four or five vertical in each column that extend down at least 2 feet below grade and up to within three inches or so of the top. 

Going to rent or purchase one of those vibrators too..


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## MTN REMODEL LLC (Sep 11, 2010)

Shopguy said:


> *I don't know what wash out of open hole for frost lift means.. * Our frost line is 42 inches, I'm going 60 down.. I can't imagine frost would have any effect.
> 
> I will be installing rebar but it wasn't specified in the original engineered drawings from IronRidge. I'm probably going to go with 1/2" rebar and put four or five vertical in each column that extend down at least 2 feet below grade and up to within three inches or so of the top.
> 
> Going to rent or purchase one of those vibrators too..


It may not be an engineering consideration in your application....

but wash out is when the hole caves in places, allowing concrete to sort of hump out or shelf out, and when ground freezes, those humps can create a vertical or disstabilizing lift up on the column over time.

Just out of curiosity, what is the project...???


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## Canarywood1 (May 5, 2012)

Shopguy said:


> I don't know what wash out of open hole for frost lift means.. Our frost line is 42 inches, I'm going 60 down.. I can't imagine frost would have any effect.
> 
> I will be installing rebar but it wasn't specified in the original engineered drawings from IronRidge. I'm probably going to go with 1/2" rebar and put four or five vertical in each column that extend down at least 2 feet below grade and up to within three inches or so of the top.
> 
> Going to rent or purchase one of those vibrators too..




Normally you only need to go 6 inches below the frost line, which in your case would be 48 in., your going an extra 10 feet down that you really don't need to do?

Be careful with that vibrator also, improper use can do more harm than good.


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## User02 (Sep 17, 2015)

Canarywood1 said:


> Normally you only need to go 6 inches below the frost line, which in your case would be 48 in., your going an extra 10 feet down that you really don't need to do?
> 
> Be careful with that vibrator also, improper use can do more harm than good.


My project is the installation of solar panels.. We are more concerned with ground shear forces and uplift than we are most other things. 

I think you meant I was going an extra 10 inches not feet right? 

As for the vibrator.. Never used one before but from watching youtube, it would seem its quite easy.. Straight up, straight down, never keep it in one spot for more than 5 to 7 seconds or it could cause the concrete mix to stratify. Did I miss anything?


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## MTN REMODEL LLC (Sep 11, 2010)

MTN REMODEL LLC said:


> It may not be an engineering consideration in your application....
> 
> but wash out is when the hole caves in places, allowing concrete to sort of hump out or shelf out, and when ground freezes, those humps can create a vertical or disstabilizing lift up on the column over time.
> 
> Just out of curiosity, what is the project...???





Shopguy said:


> My project is the installation of solar panels.. *We are more concerned with ground shear forces and uplift than we are most other things. *
> 
> I think you meant I was going an extra 10 inches not feet right?
> 
> As for the vibrator.. Never used one before but from watching youtube, it would seem its quite easy.. Straight up, straight down, never keep it in one spot for more than 5 to 7 seconds or it could cause the concrete mix to stratify. Did I miss anything?


Did the engineer spec/call out sonotubes to the bottom..... that may be why. 
Maybe not....:wink2:


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## Canarywood1 (May 5, 2012)

Shopguy said:


> My project is the installation of solar panels.. We are more concerned with ground shear forces and uplift than we are most other things.
> 
> I think you meant I was going an extra 10 inches not feet right?
> 
> As for the vibrator.. Never used one before but from watching youtube, it would seem its quite easy.. Straight up, straight down, never keep it in one spot for more than 5 to 7 seconds or it could cause the concrete mix to stratify. Did I miss anything?



No 10 ft.is what i said, your going an extra 12 inches in each pier, that's 10 feet in 10 piers.


As to the vibrator, it depends on what slump the concrete is when it's placed.


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## concretemasonry (Oct 10, 2006)

The frost dept for a free-standing deck is only a personal guide, but some municipalities have prescriptive details for all structures that does not make sense from an engineering standpoint.

Obviously, no one would go with footings not down below frost since the heaving will direct all rain and snow melt back toward the house. Any damage to the connection is already been done and will stay that way until corrected.

Frost heave effects do not always go go away after a melt.

Once you attach a deck to the house everything is different.

Sonotubes full depth are far superior to having a rough outer surface of the poured concrete. The ground freezes from the top down and it can raise a deck upward by pulling it upward, so the smooth sonotube surface minimizes and upward pull.

Dick


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## MTN REMODEL LLC (Sep 11, 2010)

ShopGuy.... No insult is intended here at all... and you mentioned you are an engineer, and I have no idea how critically demanding the specs are on this...

BUT, have you ever done this work before.???

On the one hand you mention that you are concerned with stability and uplift, but on the other hand you seem sort of uncerned with frost heave and even rebar,,, that your engineer apparently left out of specs....

and 1K of sonotubes seems unsettling to you, but I would imagine a project requiring 20" sonos @60" depth is relatively an important structural issue and 1K of sonos should be a relatively minor issue.

I'm all for saving needless costs, just something here I don't understand.

Good luck


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## User02 (Sep 17, 2015)

MTN REMODEL LLC said:


> ShopGuy.... No insult is intended here at all... and you mentioned you are an engineer, and I have no idea how critically demanding the specs are on this...
> 
> BUT, have you ever done this work before.???
> 
> ...


The original quasi -"one size fits all" engineering calls for a specific depth and diameter of the columns which is 5ft deep x 20 inches diameter. The columns are also to be flush with the grade and the 3 inch pipe embedded into the columns to rise a maximum of 30 inches above grade. 

I am extending this 30 inches of 3 inch pipe to 60 inches above grade because my project sits on a slope. 
To compensate for the extra height, and thus the extra wind loading, I am making the following changes:
1) Increase the diameter of the column below grade from 20 to 22 inches 
2) Increase the depth of the column below grade from 60 to 72 inches
3) Extend the column above the grade to a point where only 30 inches of the 3 inch pipe is showing. 
This is done because too lengthy of a pipe between the supported structure and the concrete, could allow too much deflection of the pipe. So by extending the 20 inch column up above grade with the pipe, we remove the concern for the pipe bending. 

4) We have added an extra pier support. If I built it to the engineering specs, I could have gotten away with just 6 piers.. I'm using 10.

The original specs did not call for rebar.. Certainly can't hurt to add it as I'm all for exceeding requirements.

I've worked with concrete before but not this type of work. I've even made short (20 inch) columns, but they were just fancy raised pads to put a cargo container on, not a solar system support structure.

This is a solar panel system.. Going to look almost identical to the one in the photo below. The difference is that mine is mounted on a slope.. While the solar array will remain level, the supporting pipes will extend down further to keep it that way. To stay within engineering specs for the exposed piping coming up out of the concrete, I plan to use sonotubes above grade.


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## jlhaslip (Dec 31, 2009)

If it were me doing this, and I had access to those drums, I think I would be cutting them down to about a foot tall and adding a length of sono tube material to the balance of the height in order to reduce concrete costs. You might be able to get away with an 8 inch sonotube, but I am not an Engineer. Check with the manufacturer to see if this would fit the specs for the solar panel installation. They really don't weight that much. 

Here is a calculator to assist with the concrete costs for the project. You need to know the price per cubic yard of concrete and the heights and diameter of the different sections, but If I was a betting man, I would bet there is a savings by reducing the concrete volumes and using sonotubes, IF the specs would allow for smaller sonotubes, it would be a bonus.

http://www.calculatorsoup.com/calculators/construction/concrete-calculator.php

Calculate the costs for the full height of the 20 inch drum versus a stepped design including the cost of the smaller diameter sonotubes.

Also, aren't the panels more effective if they are tilted according to the distance from the equator somehow? I would think there is a specific angle according to the latitude they are installed at. Laying them flat just doesn't sound like a good thing. They would collect debris and may not be as efficient in terms of solar collection.


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## User02 (Sep 17, 2015)

jlhaslip said:


> If it were me doing this, and I had access to those drums, I think I would be cutting them down to about a foot tall and adding a length of sono tube material to the balance of the height in order to reduce concrete costs. You might be able to get away with an 8 inch sonotube, but I am not an Engineer. Check with the manufacturer to see if this would fit the specs for the solar panel installation. They really don't weight that much.


The engineering calls for a 20 inch diameter post hole. they do not specifically call for sonotubes but I'm going to use them anyhow. 



> Here is a calculator to assist with the concrete costs for the project. You need to know the price per cubic yard of concrete and the heights and diameter of the different sections, but If I was a betting man, I would bet there is a savings by reducing the concrete volumes and using sonotubes, IF the specs would allow for smaller sonotubes, it would be a bonus.
> 
> http://www.calculatorsoup.com/calculators/construction/concrete-calculator.php
> 
> Calculate the costs for the full height of the 20 inch drum versus a stepped design including the cost of the smaller diameter sonotubes.


To find the volume of any column, calculate pressure within a hydraulic system, or any other function involving cylinders, its real easy.
Just multiply the radius x the radius x Pi.. So a 12 inch column would be 6 x 6 x 3.1415 which gives you the area of the circle.. then just add the length of the column to get the volume.



> Also, aren't the panels more effective if they are tilted according to the distance from the equator somehow? I would think there is a specific angle according to the latitude they are installed at. Laying them flat just doesn't sound like a good thing. They would collect debris and may not be as efficient in terms of solar collection.


Yes.. In our area, the panels need to tilt 33 degrees to effectively split the difference between winter and summer radiance.


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## User02 (Sep 17, 2015)

jlhaslip said:


> If it were me doing this, and I had access to those drums, I think I would be cutting them down to about a foot tall and adding a length of sono tube material to the balance of the height in order to reduce concrete costs. You might be able to get away with an 8 inch sonotube, but I am not an Engineer. Check with the manufacturer to see if this would fit the specs for the solar panel installation.* They really don't weight that much. *


Oops.. I missed this part.. 

We aren't worried about weight.. your right that solar panels don't weigh much.. in fact, the pipes holding the panels will weigh more than the panels themselves.. each panel is only 50 lbs.

With solar, they apparently worry far more about uplift and shear.. Uplift being the obvious where the wind hitting the back of the panels wants to turn them into air born sails. 

But I think more importantly is wind shear.. the ability of a strong wind to push on the panels and cause the concrete columns to shift around in the soil.. much like the wind pushing over a tree, I believe the concern is more centered on the wind shifting the foundation or just folding over the pipe structure like bending a drinking straw.


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## Auggie56 (Dec 7, 2012)

concretemasonry said:


> The frost dept for a free-standing deck is only a personal guide, but some municipalities have prescriptive details for all structures that does not make sense from an engineering standpoint.
> 
> Obviously, no one would go with footings not down below frost since the heaving will direct all rain and snow melt back toward the house. Any damage to the connection is already been done and will stay that way until corrected.
> 
> ...


Just read a short tip on another web sight, where you wrap thick plastic sheeting, around the outside of the tube, so there is slippage, and the freezing ground will not pull the tube up. Sounds good to me.


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## jomama45 (Nov 13, 2008)

concretemasonry said:


> The frost dept for a free-standing deck is only a personal guide, but some municipalities have prescriptive details for all structures that does not make sense from an engineering standpoint.
> 
> Obviously, no one would go with footings not down below frost since the heaving will direct all rain and snow melt back toward the house. Any damage to the connection is already been done and will stay that way until corrected.
> 
> ...


Dick hit the nail on the head here. Sonotubes give a smooth, uniform surface that is resistant to frost heave, unlike a 55 gallon drum that has ribs to it. Personally, I'd shop around for the sonotubes. I've found pretty extreme prices variances (and quality) between various ready-mix plants.


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