Floor pour dilemma, any quick input?

[HunterDan]

Havent made a build thread yet (but is coming), but im just about done my 40x48x16 pole barn. We were going to do concrete (6") tommorrow and friday, but today my concrete guy calls and says he wants to do my floor in 2 pours, instead of 1 like we had originally talked about.


So, i guess my dilemma is, should I just let him do it in 2 pours, and deal with a joint in the floor, or should I find someone who is willing to do it in one pour? (which may have to wait until spring at this point)


I know there would have to be saw cuts in the single pour slab, but im thinking that they are relatively small compared to a full blown joint?


Any input is appriciated!

 

[bygasper]

I wouldn't allow it to be done in 2 pours, but that's just me. The joint will be significant and would be a nuisance to me.

 

[ford33]

And the reason he told you he wanted to do it in two pours?

 

[Hpozzuoli]

Two pours you run the risk of uneven slabs and separation if there is significant settling.

 

[Gerald O]

Put rebar in it and you won't get any separation with multiple placements. A cold joint isn't much different than the crack-throughs that you'll get in your control joints. It's better than risking the whole floor from running out of time.

 

[HunterDan]

I wouldn't allow it to be done in 2 pours, but that's just me. The joint will be significant and would be a nuisance to me.

yea i figured itd be a nuisance to have in the middle of the garage.

As far as the reason, he didnt really have one. My barn has 16' wide lean to's on each side, and the back 15' is enclosed. They will be getting concrete to. So he told me theyll do half of the main building slab, and one lean to enclosure one day. then will come back and do the other half of the main building, and the other side lean to enclosure.

 

[boobag]

use a key joint where you will divide the floor.

 

[Slowgsr]

If they do good work and know what they're doing. There should be no issues.

 

[Garage Dog]

Hunter,

The answer to your question depends on how picky you are, how you will use the building and if you can wait till spring for a different contractor. There can be benefits to letting the ground go thru a freeze thaw cycle depending on the extent of prep work and how it was done.

Bottom-line is that for whatever reason the guy is not comfortable with one placement. One of the primary issues with concrete is having adequate finishing time given the conditions, if you don't, things get rushed and things start looking a little rough around the edges. That affects aesthetics and functionality.

Does the 40 x 48 include the 16' lean-to(s)? If not does that add two more slabs at 48 x 16?

Maybe we should ask how the barn will be used and what you personally perceive as the drawback to letting him do it in 2 placements?

If this guy is good, separating the main building into two pours should not be that different than having a control joint in the middle of your building as far as functionality goes. It isn't like you will have a form in the middle of the building, think about it as if one edge of the first slab ill become the form for the edge of second placement the next day or whenever. If you have specific concerns ask him to overcome your objections. If you are not satisfied with his answers, you have yours.

Aesthetics of the job would be my primary concern regarding two placements. One of the things I have seen even if done well is that the concrete can cure to a slightly different color given the temperature, humidity, how the mix came from the supplier, etc.

Do you know how large his crew is? How many finishers? Does he just do masonry work?

The thing that would bother me is that he committed to a single pour and now wants to do it in two... Again, what changed? It's not like the temp just spiked into the 90s in the middle of the summer and his finishing time was just reduced.

What about suggesting that he place the concrete in the main building first and do the two lean-to(s) the next day?

Have you agreed on control joint placement? If not think roughly every 10' in both directions everywhere.

If you do agree to a joint in the middle of you building which I don't know I would if this is your baby, make sure the two slabs are well pinned together with re-bar.

That's my quick input, Good Luck!

GD

 

[SunsetsAndFriends]

You stated that you're questioning the possibility that the center cold joint resulting from two separate pours will be larger than saw cuts. The fact that you're asking questions says to me that you're perhaps not comfortable with something, perhaps more than just the control joints. I don't know. That's something I recommend reflecting on.

Typically I pour my own flatwork. About 18 months ago I didn't have any help, so I hired a contractor. I had seen some of his work in my area and it was good work. And I was able to observe him and his crew preparing for a pour. They were very attentive to details.

Well, I ended up being dissatisfied with the quality of the work he did for me. I ended up being the first job of the year, which may have contributed to the poor finishing. But in advance I had a nagging feeling that I should have hired someone else. When trying, by email, to nail down some details of the job, he just said that when he arrives to do the work we can sort everything out then. I agreed. But should not have. In hindsight, it said that my concerns as a customer were not worth his time.

That's a little of my story for thought.

If two pours were okay with me, I think I would lean toward pouring the main barn section during the first pour and then bump outs on for the second pour. I would also want one continuous grid of rebar for the entire slab.

Also, for the cold joints, I would ask for foam expansion joints to be placed. There are foam joints where the top 1/2" or 3/4" is perforated. That way after the concrete is cured, you could use a needle nose pliers to pull out the top portion of the foam expansion joint, tearing at perforation. The gap left behind could then be filled with an expansion joint sealant, such as Sika brand or a polyurea/sand mix and ground. The later would work nice if you were planning to coat the floor and wanted to hide the seams.

My 2 cents.

 

[HunterDan]

thanks for all the input! The barn is going to be used as a shop. working on the truck or tractor, etc, storing stuff, planning on getting a lift, etc.

The main barn slab is 40x48. the lean to's are the 16x48, but only the enclosed 16x15 portions on each side are getting concrete. That was the original plan, to pour the main slab one day, then come back and do the two 16x15 slabs another day.

im not sure how big his crew is, but i believe he has 3 finishers

 

[Shiftless]

thanks for all the input! The barn is going to be used as a shop. working on the truck or tractor, etc, storing stuff, planning on getting a lift, etc.

The main barn slab is 40x48. the lean to's are the 16x48, but only the enclosed 16x15 portions on each side are getting concrete. That was the original plan, to pour the main slab one day, then come back and do the two 16x15 slabs another day.

im not sure how big his crew is, but i believe he has 3 finishers

If you are planning a lift, are you putting extra concrete under the load points to act as a footing? Better have that marked out and formed ahead of time.

 

[SunsetsAndFriends]

If you are planning a lift, are you putting extra concrete under the load points to act as a footing? Better have that marked out and formed ahead of time.

Definitely! Great point, Shiftless!

 

[HunterDan]

Definitely! Great point, Shiftless!

From the research I've done, I thought 6" was plenty for a lift?

 

[SunsetsAndFriends]

From the research I've done, I thought 6" was plenty for a lift?

I would go by the manufacturer specs of the lift you will be installing.

 

[Shiftless]

I would go by the manufacturer specs of the lift you will be installing.

Excellent advise there from DoItMyselfToo

Lots of guys pour only 4 inch floors. Going 6 is beefy! Are you installing mesh or rebar?
What psi are you going to spec for the mud?

Here is a screen shot of a spec page from Eagle lifts as an example... (I am in no way affiliated with any company that installs lifts)

 

[HunterDan]

Well the problem with that is, as I'm sure a lot of you know, after the construction of this, my wallet is pretty light. I have no idea on which kind I'm getting, so the idea was if I did 6", down the road when I can get a lift, I can put it anywhere.

The concrete is 3000 with fiber, and the plan was to use wire mesh

 

[MagKarl]

Two pours is no big deal in my opinion, provided you have prepped properly. Well compacted crushed rock and run rebar across the cold joint.

 

[Kensgarage]

Good Gawd. That pour is nothing. Quit dealing with idiots and call the CONCRETE company. Tell them the size and get a number for someone capable of doing it in one shot.
' Contractor" That's. CON tractor is a loose term. General contractor is worse.That's like a GP.
All they have is phone numbers of guys that give THEM the best price so they can stiff unsuspecting dolts and pocket a bunch of money.

 

[gungatim]

you could ask them to do a hidden joint. my Grandpa-in-law had his driveway done and they somehow did regular joints but then skimmed over the top so you couldn't see them. the contractor said it was a good way to do it if you want a smooth surface. small hairline cracks develop where the joint is, but is barely noticeable unless you look for them. the driveway was still smooth and level last I saw it but that was 5 yrs. ago when he passed so no idea if it still looks that way now...

anyone else seen this kind of joint before? or was it something he made up and is frowned upon?

 

[HunterDan]

Talking to him more today, he said by doing a cold key joint (or something like that), I won't have any issues with slab separation, or un evenness. And that the gap will not be as big as I think. (I'm expecting like expansion joint size)

The area was flat to begin with, we brought in 8 tri-axles of bank gravel to bring grade up a little, then 8 tri axles of # 2 for the base, and compacted with a roller. I'm pretty confident in the prep, my main concern was having a cold joint in the middle. It seems some say no big deal, and some say no way....so I'm still at a cross road.

Also, as far as temps go, am I still safe? Low 50's during the day and low 30's at night. Barn is complete, except for garage door isn't on yet.

 

[joes169]

I'm a concrete and masonry contractor, I think you have nothing to worry about. We usually have a small crew, and would likely pour it in two pours as well, as it actually give you better access to the slab for floating. I'd be willing to put our slabs against almost any of our competitor's that pour it in one shot. A good crew, that cares, can blend the two slabs together w/o issue. We pour quite a bit of exterior flatwork as well that needs to be split in numerous pours (everyone does at some point) and we use a small radius (1/8") edger on the first slab, trowel it shut on the second pour, and saw it open after the concrete cures to match the rest of the sawn joints. 99% of people couldn't tell that it was poured in more than one section once it cures.............

BTW, you're temps are just fine yet, especially inside a building. You'll be surprised how much heat the concrete makes in the first 2- days inside.

 

[HunterDan]

^^ Good info there thank you! I was nervous about the temp so that's good to hear.

I met with him again today, and he took me to another building he did in two pours. I can say that honestly looked great, and was hard to tell. The joint was slightly larger than the saw cuts, but overall looked good. It was about 2.5 years old.

So I think I'm gonna go ahead and let him do it in two

 

[SunsetsAndFriends]

you could ask them to do a hidden joint. my Grandpa-in-law had his driveway done and they somehow did regular joints but then skimmed over the top so you couldn't see them. the contractor said it was a good way to do it if you want a smooth surface. small hairline cracks develop where the joint is, but is barely noticeable unless you look for them. the driveway was still smooth and level last I saw it but that was 5 yrs. ago when he passed so no idea if it still looks that way now...

anyone else seen this kind of joint before? or was it something he made up and is frowned upon?

There are several products/techniques for achieving a "no bump" control joint. I personally don't like them because often a zip strip is used, which is a piece of plastic that gets embedded under the surface of your concrete. If later you want to grind your floor for coating purposes, then you have to deal with it then. Also, I think the scored or cut joints look better, more traditional.

 

[SunsetsAndFriends]

^^ Good info there thank you! I was nervous about the temp so that's good to hear.

I met with him again today, and he took me to another building he did in two pours. I can say that honestly looked great, and was hard to tell. The joint was slightly larger than the saw cuts, but overall looked good. It was about 2.5 years old.

So I think I'm gonna go ahead and let him do it in two

That's positive. Sounds like this contractor might be a good bet.

 

[HunterDan]

Thank you guys for all the input! I'm gonna start a build thread here soon when I can get a free hour or so