Concrete Piers Done Right | Sonotube Rebar Cage Construction

This is part 1 of constructing the foundation piers for our timber frame porches. Rebar cage construction for sonotubes.

[@goldengoat1737]

I love the detail of this method…. Building things to last longer than you you is something to be proud of

[@ncbarndobuild]

Thanks for the comment and watch!

[@timb4956]

I own a concrete company, and yes agree! Rule of thumb, 3” away from the edge of forms or tubes, etc

[@ncbarndobuild]

I have yet to see any post frame builders on KZbin put rebar in their columns. Seems important in my mind.

[@jojiran]

@@ncbarndobuild I think you are doing the right thing. In geographies like the middle east where concrete is the norm , you cant get approved without rebar for buckling loads . However the structural loads are much higher in those regions.In similar circular sections , Ive seen cross bars also being added where you have the circular ebars

[@ncbarndobuild]

@@jojiran that’s interesting. Thanks for the feedback.

[@coincollectingfun]

Liked and subscribed! Excellent information and thank you so much for sharing!

[@ncbarndobuild]

Thanks! Lots of videos on a variety of topics all designed to help others learn from our failures and successes.

[@jshepard152]

That's a fancy rebar cage. I usually see those referred to as rebar Wheel Spacers. Thanks for the tips.

[@ncbarndobuild]

Wheel Spacers that sounds about right. Thanks!

[@lindakleckner215]

Do those round spacers slide out and you patch the cement where they were? OR; Do they become part of the column?

[@ncbarndobuild]

@@lindakleckner215 they clip on the rebar so you can move them around if need be. They stay in the column permanently.

[@lindakleckner215]

@@ncbarndobuild What a good idea!👍Thank you!

[@chrisduncan326]

Brilliant, thanks for sharing

[@ncbarndobuild]

Thanks. I learned by spending some time with concrete professionals down in Austin, TX. I asked lots of questions to figure out how the pros do it.

[@chrisdaniel1339]

I 100% agree with putting a rebar cage in sonotubes, I like that you elevated the cage and centered it, but even better is to add a Bigfoot Systems bell shaped form to the bottom of the sonotube pier and the rebar cage. The holes for each Bigfoot pier can be drilled with an earth auger of the appropriate size on a skid steer or mini excavator. There is less disruption of earth than using an excavator alone to dig oversize holes. By using a bigfoot that is 26" at the bottom of the bell and then a 12" diameter sonotube with a rebar cage you only need about half the amount of concrete and end up with a pier that is stronger than a 24" sonotube alone pier. Make sure you vibrate your piers to get air out and consolidate the concrete around the rebar. Each big foot is approx. $31 and you save much more than that by using fewer yards of concrete. These Bigfoot forms are dead simple to use and exceed building code specifications in the US and Canada. There is no reason not to use them. And no I do not work for them, I am just a huge fan of great products and doing a job right the first time

[@ncbarndobuild]

There is always more than one way to do something so I appreciate your comment and sharing with the viewers. The only thing I would add is to make sure an experienced structural engineer is ok with the pier you described for the structure it is supporting. There are more videos in the series including the pour, results, and how I attached the Douglas Fir posts to the pier if any of that interests you.

[@beassttttt8gdxrgchru]

I’m using the 20inch big foot footings, do you know how many 80lbs of concrete I need for the footing?

[@chrisdaniel1339]

@@beassttttt8gdxrgchru The BF20 Bigfoot Forms require 1.75 cu.ft of concrete, each 80 lb bag of concrete is 0.60 cu.ft, so each form requires 2.92 bags of concrete. Do not forget the rebar cage. A local shop can bend circular rebar rings so all you need to do is tie on the vertical rebar inside the rings and you are in business. Rebar rings must go on the outside of vertical rebar to maximize tensile strength. Make sure rebar cage is lifed off the soil on feet so it will be fully incased in concrete, if rebar rests on or in the soil it will start rusting immediately. When rebar rusts it expands and the pressure from expansion will start forming cracks in the concrete. You also need to calculate the required concrete for each sono tube you are using as 2.92 bags of concrete is for the form only. The BF20's have varying steps to accept 6" or 8" sono tubes from different manufactures. The sono tube manufacturer you are using likely has a required concrete volume per foot of their sono tube, add 10% to make sure you do not come up short filling the tube/footing. Do not forget to rent a concrete vibrator to consolidate the concrete around the rebar and evacuate any air pockets. There is good information at the Bigfoot Systems Forms website and specific instruction for trimming the form, joining the tube to the form, and its proper installation. Hope this helps.

[@beassttttt8gdxrgchru]

@@chrisdaniel1339this helps a ton thanks.

[@chrisdaniel1339]

@@beassttttt8gdxrgchru One last item, you will want to rent a laser level for the layout of the pier/footer especially if you are going to wet set anchors in the surface of the concrete in the sono tubes. If the anchors are off by even a small amount it will make your construction much more challenging. Depending on the number of piers you require you may consider just getting the concrete delivered from a redi mix supplier. Bagged concrete gets very expensive if you need more than a yard or two, it is heavy and not the easiest stuff to work with, and if you are hand mixing in batches it will take forever, its a PITA, and every batch will be a slightly different consistency and strength. If you have no other option than to used bagged concrete or hire a concrete pump truck, look into renting a Mud Mixer brand concrete mixer, all you have to do is keep the hopper full of bagged concrete mix and make sure the mix is not soupy(soupy concrete is weak concrete) and it constantly mixes concrete at a rate of 40 bags per hour.

[@columbuspalmer846]

Thanks useful information. Keep up the good work

[@ncbarndobuild]

Your welcome. Thanks for the watch and comment!

[@barrymarson9658]

Nice job

[@ncbarndobuild]

Thanks for watching and commenting

[@RiverValleyAcres]

I been on some big substation projects and this is exactly how we done it. I started my own business and gave a guy a price using rebar cages, 12” footer with 3” brick to hold the cages off the ground. The customer was shocked with my price. I’m still trying to figure out these residential customers lol. I came to KZbin to see if that’s standard for pole barns. You’re the only video I found that uses rebar! No one even pours a footing! They just stick the tubes in the ground just enough for an above ground finish reveal.

[@ncbarndobuild]

Are those bricks called Dobies? I remember looking at them when I was in Austin TX for work. I think those are better than the plastic chairs. The only reason I didn’t use dobies was because I had to pack the chairs in my suitcase for the trip home.😂 Ya I watch a lot of other KZbin professional builders and I have yet to see anyone put rebar in their piers.

[@AllAccessConstruction]

Just installed 125 piers.. agree with the rebar wheels and rebar boots ..

[@ncbarndobuild]

Dang that’s a lot of piers! Thanks for the feedback.

[@adk1guy]

I did some without footers but we dug down to bed rock, drilled the bedrock and torqued in hollow 3/4 x 12" expansion bolts and pumped non shrinking grout in until full. Then we had to have 3/4 rebar threaded one one end and used threaded connector nuts to secure the uprights to the anchor bolts. Then we tied rings like yours. The tubes were 3 foot. We filled them using a helicopter with a concrete bucket, actually 2 because they could only carry 1/2 a yard, the other bucket would get half filled and the helicopter would drop one, and pick up the other.

[@ncbarndobuild]

Dang, are you building on the side of a mountain? What are your point loads on those piers? Sounds like your project is way more complex than mine.

[@cassielectricinc.4814]

Up voted based on the "lets pull up a chair" pun. So far the rest of the video is good.

[@ncbarndobuild]

Thanks for the watch!

[@DeltaWhiskey89]

What diameter rings did you use? And what size bar, 4 bar?

[@ncbarndobuild]

Rings were 18” diameter because the wheel spacers were 3”. And yes #4 bar which was what my engineer called for in the prints.

[@kevintotanes8760]

Looks great. But do you think they would provide the same structural integrity if the cage was square (instead of circular)?

[@ncbarndobuild]

I thought about doing squares. I don’t know if the wheels would hold it away from the sides like it does with the circles. Great question. Maybe there is a structural engineer somewhere that can chime in?

[@bbdaman]

​@@ncbarndobuildI think I'm going square and less lol

[@ncbarndobuild]

@@bbdaman 😂

[@drumswest5035]

Im in structural engineering and there is no difference in Square or round for strength, round is popular because its easier for form work with a sonotube. Sometimes the client or architect will ask for square. Note that the ties should always have a hook on them weather they are round or square

[@montanausa329]

Now you’re ready for one big telescope

[@ncbarndobuild]

That’s an idea!

[@bartekdem5569]

The best way to cut these is to use grinder with disc for concrete

[@ncbarndobuild]

Interesting. That’s a good suggestion never thought about trying that. Thanks for the tip!

[@jonorcutt3061]

Please reply with the link to the second video in this series. Thanks!

[@ncbarndobuild]

This is the 2nd video. kzbin.info/www/bejne/qqrKdGueaKdlp5Ysi=Q0WtOrIGDlLsZInK

[@ncbarndobuild]

And here is video 3 where you can see the pour results. kzbin.info/www/bejne/fpW1Za15qrqXmZYsi=c1ClE5RVD2WwulH0 Thanks for watching!

[@sandywjo5]

Are you supposed to leave the sonotube in the ground permanently? If not how do you pull them off?

[@ncbarndobuild]

The tube does not go all the way to the bottom. I would guess maybe 12 inches below grade is all the further I put them. You would have to dig them out I guess. I pulled off what was just below grade but there is probably 6-8 inches still around the column below grade.

[@sandywjo5]

@NC Barndo Build ours has to go all the way to bottom because of larger hole dug up from old footer. TOP also has to be level with driveways cause basketball system going in next to driveway.

[@ncbarndobuild]

@@sandywjo5 if I was in your position I would leave the tube in place and backfill prior to pouring for extra support. Remove what is above ground and leave the rest.

[@LoliLife69]

Would it be good to put a rebar in the center also?

[@ncbarndobuild]

I had to drill a 1-1/8” hole in the middle for the threaded rod that attaches the timber to the pier so the rebar would of been in the way with a stick in the center. Here is the video detailing the install and how I epoxy the rods that connect the Timbers to the concrete. kzbin.info/www/bejne/qoXQoGVvjN2WZ6ssi=6Wjz3VFvdV65H1D- Also my engineer only called for 3 vertical pieces so it wasn’t required for me put a 4th piece in. You can put one in the middle if you want and it isn’t in the way.

[@fluffymittens24]

One wrap around with the wire is plenty. Because once it's in the concrete the wire tie won't matter, it will be the concrete holding the rear not the wire.

[@ncbarndobuild]

I struggled at first trying to wrap them too tight and snapping the ties. It was my first time working with rebar and making cages so there was a bit of a learning curve. Thanks for the feedback!

[@Mrdubomb]

Wouldnt it be better to weld the rebar together? What would happen if you welded "non weldable" rebar? How long do you usually have from digging the holes to setting the tubes in the ground? Im using cardboard tubes which cant get wet but also need to coordinate with building inspector and the hole digging dude.

[@ncbarndobuild]

I did not buy weldable rebar nor do I have a welder or have any experience welding. All you need the wire or welds for is to hold the cage together during the pour. Welding would probably be preferred if you were doing really tall columns. As for the sonotubes I am not sure how long they will last in the weather. I planned the project during a stretch with no forecasted rain. The tubes I used had a coating on them in case of rain but I have no idea how long they would last in wet weather.

[@lindakleckner215]

Once your concrete is dry and solid, do you trim the cardboard tube& take it off? Nevermind I'm reading other people's answers...

[@peetky8645]

welding will weaken rebar in the heat affected zone.

[@drumswest5035]

No concrete project i have ever worked on welds their column cages together, weldable rebar is sometimes used for anchors to embed plates etc. Column rebar properly done is more than sufficient but make sure the ties have hooks, round or square. Spiral ties can be used for round columns as there are only hooks at top or bottom of the spiral

[@bryanford1139]

1:11 Yep,100% Bro...worse yet the action of corrosion will actually work almost like water freezing and will break apart your concrete....ever see bridge abutments and columns that are breaking away and exposing the rebar...this is why.

[@ncbarndobuild]

Interesting, I did not know that but I have I have seen that before on bridges. Thanks for sharing your insight on the topic and watching the video.

[@user-ft1zo4kd6t]

Shouldn't your laps be 40X the diameter of of the rebar? Or 135 degree hooks? I use a skill saw for the sonotube laying on the ground.

[@ncbarndobuild]

Excellent point. A lap is defined as 2 pieces of reinforcing bar that are overlapped to create a continuous line of rebar. I would say that since this is only a single bar that is bent in a circle it is not technically considered a lap. However, in the end if the inspector disagrees then his decision would trump my explanation. Maybe someone with more experience will chime in.

[@drumswest5035]

Alway hook your ties, a lap is not sufficient for strength in a tie.

[@christopherhaak9824]

Wet set and dry set brackets are an engineered product in regards to pull out and shear values. They work when spaced far enough away from the footing edge. The reason no one uses rebar in the column footings is because it's not necessary. There is no tension situation in the column that rebar addresses. It's an extra thing that is a waste of time and money for this application.

[@ncbarndobuild]

Not a waste of time nor money when the engineered plans specifically call for reinforcement and the building inspector checks your work against the sealed plans like ours did. At any rate you should always check your local building code if you are unsure because not all districts are the same.

[@bertnerny]

What is the name of the plastic bases?

[@ncbarndobuild]

They are called rebar chairs. There are several different kinds available.

[@adk1guy]

where are the footers below the frost depth? Without footers piers are tippy and may sink due to insufficient bearing area

[@ncbarndobuild]

My engineer said with a 24” diameter pier and the soil compaction test results they would support the weight we had planned. The soil here is like concrete when you go down about 2-3 feet. The engineering firm that did the compaction test actually stopped the test early because we hit the limit on their scale.

[@lindakleckner215]

I think the issue is how far down the ground freezes in winter, right? Around where I live you're supposed to set footers three feet or more so if the freezing thaws out the liquids will follow down the footer and keep on going down into the ground where the soil isn't froze off the bottom of the footer, you know.

[@ncbarndobuild]

@@lindakleckner215 yea the frost line is important but it is not the only factor. Not all soils are appropriate to build on and I highly recommend having a soil compaction and analysis test done by a professional engineering firm prior to building. It was especially important for us since we had fill dirt on the back side to level the build site. The frost line here is 12 inches but the compaction test showed that we needed to go deeper in order to get to soil that would support the building weight.

[@lindakleckner215]

@@ncbarndobuild yeah, I understand there's a lot of things to consider: if it's a lot of sandy soil or hard rocks underneath, or if the moisture stays too long during the soil drainage testing. I thought the conversation was just about the one consideration.

[@drumswest5035]

Your ties should have a hook on them to be correct

[@ncbarndobuild]

Is this in reference to the CRSI manual? I don’t see where a hook is required in any of the ties listed in the manual. The manual shows 5 types of ties and I tried to emulate the “wrap and snap tie”. Always willing to learn if you can point me to a reference.

[@butopiatoo]

Wagon wheels? you gotta be kidding

[@ncbarndobuild]

My lame attempt at humor.😳Thanks for watching.

[@SongwritersAndPoets]

zip ties would be quicker

[@ncbarndobuild]

Maybe so. Not sure what my building inspector would say so I went with what was specifically designed for this application.