# cardboard concrete tubes



## Grampa Bud (Apr 6, 2009)

A 10-12" diameter footing will slowly sink over several years unless you are building on rock in which case you wouldn't need footings. I don't know the formula for figuring pad area under the leg to support a certain load range, but I have a 40' x 8-12' deck that I have to tear down because I put in 12" round x 4' deep footings back in 1986 and it is looking like the floor of a carnival funhouse just because I didn't want to put out for 2-3' sono tubes. Will I ever learn???


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## Gary in WA (Mar 11, 2009)

I think they would work. Dig below frost line for your area, pour a squarish flared foot on gravel with a re-bar sticking up for the later pour in the tube and attachment bracket for post. Sizing piers, and frost proofing footings: http://books.google.com/books?id=1g...=X&oi=book_result&ct=result&resnum=3#PPA31,M1
Gravel for frost: http://rockproducts.com/mag/rock_aggregates_prevent_frost/
Foam protect piers: http://www.oikos.com/esb/43/foundations.html
2006 deck code, footings, beams, joists, ledgers: http://www.awc.org/Publications/DCA/DCA6/DCA6.pdf
Be safe, Gary


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## Daniel Holzman (Mar 10, 2009)

The main purpose of a sonotube is to make it convenient to place concrete. The cardboard adds no strength to the concrete, and if the cardboard is not stripped off the concrete, it eventually rots anyway. Absolutely no reason not to use a PVC tube, unless you dislike the appearance of PVC pipe and you plan to leave part of it exposed above grade.

By the way, check previous posts regarding the need for standoffs (column supports) to keep your wooden column posts from directly contacting concrete. Simpson makes a line of them, other companies do as well.

Grampa, if you put in 4 foot deep, 12 inch diameter footings and they are sinking, you must be in some of the worst soil on earth. Very unusual in my experience. In most locations, you can use an 8 inch diameter tube, however you need to check with the local building inspector, and of course the required diameter depends on local soil conditions. If you are building over fill, you need a thorough soil investigation before you can size the footers, but for normal soil, there is a presumptive allowable bearing pressure in the code books.


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## Willie T (Jan 29, 2009)

Grampa Bud said:


> A 10-12" diameter footing will slowly sink over several years unless you are building on rock in which case you wouldn't need footings. I don't know the formula for figuring pad area under the leg to support a certain load range, but I have a 40' x 8-12' deck that I have to tear down because I put in 12" round x 4' deep footings back in 1986 and it is looking like the floor of a carnival funhouse just because I didn't want to put out for 2-3' sono tubes. Will I ever learn???


You sure you typed that like you meant it to read?

You feel the trouble is due to you putting in piers a foot *deeper* than what you suggested? Perhaps your foundation heaved *upward* to give you that roller-coaster look instead?

And could you run the size of that deck by us one more time? I can't visualize it.


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## Scuba_Dave (Jan 16, 2009)

Willie T said:


> You sure you typed that like you meant it to read?
> 
> You feel the trouble is due to you putting in piers a foot *deeper* than what you suggested? Perhaps your foundation heaved *upward* to give you that roller-coaster look instead?
> 
> And could you run the size of that deck by us one more time? I can't visualize it.


No - I think he is saying he needed 2-3' WIDE sono tube for his soil
I think it depends upon your soil conditions for width
We have very rocky soil & digging I hit ledge @ around 42"


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## Willie T (Jan 29, 2009)

Ok.... 27" diameter tubes? Or 24" to 36" maybe. I see now.


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## Baron (Jan 6, 2009)

mike6x7 said:


> I'm about to build a deck and my question is do I have to use cardboard concrete tubes ( sonotubes ) or could I just use PVC plastic tubes to pour the footings? where I work I can get 10-12 inch pvc plastic pipe for free, and if I can avoid paying $9 a tube ( also have several future projects that I will need footings for) that would be a good thing. And if I can't used PVC, could someone please tell me why? I'm one of those that has to know the reason behind everything. : )
> I've searched the site and couldn't find this covered anywhere else, but if it is, a link to that forum would be appreciated too. Thanks



Since you have them for free use them on a 20" footing base,
The standard for a column is a footer minimum of 20" and at least a 10" tube and I always throw re-bar in mine.(I've used 8" tubes on small decks if they are reinforced with rebar bent into the footing)

Do not expect a sono tube or 12" column to work without a footing under it. Footings can be poured in a prepared hole, at the width desired by flaring out the bottom with your shovel and post hole digger and the tube added after 10-12" concrete is poured. Drop in the form (PVC or sono and back fill plumb ending them above ground.


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## mike6x7 (Mar 28, 2009)

Thanks everyone. Yes, I planned on placing the columns on poured footings, but I just wasn't sure about the tubes. I planned on using a cut-off wheel to cut the upper 3 or so inches off the PVC after the concrete has cured. Thanks again.


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## rahfiki (Jun 23, 2009)

Where Im from, most our decks we use 8" piles, however we go a minimum 8' deep.

I believe it is the depth that helps stop heaving. Need to get way below the frost line. Perhaps you dont have a frost line where your from:laughing:


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## stuart45 (Jun 20, 2009)

I've never seen Sonotubes used in the UK. What is their advantage compared to just digging out the hole and concreting it? Do they just save a bit of concrete?


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## stadry (Jun 20, 2009)

IF you can dig a smooth-wall's hole, don't worry about it,,, rarely do we see that here because of clay in the soil,,, frost can & will ' lift ' supporting columns as it's molded to the conc column


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## stuart45 (Jun 20, 2009)

Thanks IRC, I can see what you mean. we do have clay soil and frost heave around here, so these could be usefull. A bit of advanced American technology to talk about over a pint down the pub tonight.


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## jomama45 (Nov 13, 2008)

I agree completly with Daniels info, but would add in what IRC said. In our region, this is ths simplest, effective way to install deck footers.

If your seeing large settlement in 12" piers in OUR soils, here's a few scenarios I would look into:

- Where the holes tapered or rough (no tube used) & heaved due to frost. Often times when a tube heaves, ground can fall in at the bottom, not allowing the tube to return back down when the frost recedes.
- The tubes where poured on backfill or loose fill.
- All undisturbed soil wasn't removed after a power auger drilled the holes and/or the bottom of the hole wasn't tamped.


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## jogr (Jul 24, 2007)

mike6x7 said:


> Thanks everyone. Yes, I planned on placing the columns on poured footings, but I just wasn't sure about the tubes. I planned on using a cut-off wheel to cut the upper 3 or so inches off the PVC after the concrete has cured. Thanks again.


Mike, cutting off that 3" of PVC after the pour sounds like it would be more trouble than it's worth. How about use your PVC but leave each one 3" short. Buy one sonotube (they are actually pretty cheap) and cut it into 3" bands. Duct tape the 3" band to the top of your PVC. The day after the pur you'll be able to easily remove the 3" sonotube section.

The duct tape will hold that section in place with no trouble as their is very little pressure on the top 3" of the pour. I had to extend a 16" diameter sonotube another 5" this way and it held together just fine.


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## Willie T (Jan 29, 2009)

Uh.............. Why not just cut all the tops off the Sonotubes, (or PVC), all level with each other, BEFORE pouring the concrete?


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## jogr (Jul 24, 2007)

Willie T said:


> Uh.............. Why not just cut all the tops off the Sonotubes, (or PVC), all level with each other, BEFORE pouring the concrete?


We were talking about removing a portion of the tubes after the pour so that the top 3" of concrete could be exposed.


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## Gary in WA (Mar 11, 2009)

Or a compromise.... cut them all level (if needed), AND cut through all the way around, 3" down, *but leaving 1" of *meat in 3 locations at the cut line, which you finish cutting after it sets up. Put some tape inside on the cut line. I built my garage cupboards that way, installing hinges, pulls, and 99% of the door cut-out while on the bench, installed the face plywood with door cuts, finished the cuts, doors already gaped correctly. A real time saver.
Be safe, Gary


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## Willie T (Jan 29, 2009)

Maybe I'm just not seeing something. If this is merely a deck, and the beams are going to rest on top of the columns, what is the need to cut off 3" of the PVC tube to expose a little bit of concrete at the top?


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## concretemasonry (Oct 10, 2006)

It sounds like a combination of being cheap and a cretive architect at the same time.

For a deck do the support properly first and just use the cardboard Sontubes just as professionals do and see if you can be creative to use the plastic pipe for this or something else creative. - It is much easier to cut off the appropriate Sonotubes to fit whatever the grade finally is.

Put a little thought into whether the concrete tube diameter is adequate for the soil you have.

Dick


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