# Fall Concrete Pour



## HDS (Jun 21, 2014)

We are looking to have our old patio replaced (600 sq ft) as well as a slab for a shed (160 sq ft). The company we hired may not be able to make the schedule for this fall, but if they do, are there any watch outs we should keep in mind? I'd hate to wait until the spring, but would rather make sure the conditions are right for the concrete to cure properly. 

We are in SW Ohio and next week is mid 50's and lows in the 30's, and the week after Thanksgiving is showing highs in the 40's and lows in the 20's. Are we pretty much out of luck for this year?


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## gregzoll (Dec 25, 2006)

The plant that mixes the Concrete will make the mix for the time of the year thatthe pour is done during.

Go get some references from who will be doing the work and go talk to their previous clients.


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## Canarywood1 (May 5, 2012)

I personally would not pour at those temps, there is no way to protect a slab on grade, all it takes is one freeze while it's still green, and it's toast.


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## gregzoll (Dec 25, 2006)

Canarywood1 said:


> I personally would not pour at those temps, there is no way to protect a slab on grade, all it takes is one freeze while it's still green, and it's toast.


Actually it can be poured at lower temps now, because of the additives that they use. Along with heating blankets.


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## Canarywood1 (May 5, 2012)

gregzoll said:


> Actually it can be poured at lower temps now, because of the additives that they use. Along with heating blankets.



Well if you really want to pour at freezing temps, you can tent the site and run propane heaters for a couple of weeks after the pour, but you'll also need to run them before the pour to thaw the frozen ground, ever wonder why you rarely see concrete being poured in the winter time???


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## joed (Mar 13, 2005)

The ground under the concrete can not be frozen.
The concrete can not be allowed to freeze.
Otherwise they can pour in cold weather.


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## gregzoll (Dec 25, 2006)

Canarywood1 said:


> Well if you really want to pour at freezing temps, you can tent the site and run propane heaters for a couple of weeks after the pour, but you'll also need to run them before the pour to thaw the frozen ground, ever wonder why you rarely see concrete being poured in the winter time???


Because it is expensive to thaw out the ground.

This year they are pouring until it gets around 30 or lower during the day. The plant changes their mix for the weather, because the city is their biggest customer.

They were pouring in the middle of Winter, when the new power plant was being built.


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## Canarywood1 (May 5, 2012)

Mix designs are not changed because the weather changes, they stay the same through out the construction of the building, accelerators may be added but the only changes are the raw materials are heated along with the water,and if it's a government job ,the concrete cannot leave the yard unless it's 70 degrees.

As to the structure, it must be out of the ground before freezing weather arrives,that means footings and foundation, so subsequent concrete that needs to be poured can be protected by heat, and that's the only way to keep it from freezing.


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## stadry (Jun 20, 2009)

i think what's being said is concrete can be placed at any time of year (these birds argue about anything !),,, it just take more steps to place it correctly,,, i prefer cooler/cold weather placing rather than dead hot,,, enjoy your day


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## jomama45 (Nov 13, 2008)

I'm probably the only guy here who pours residential concrete for a living in a cold climate like yours. I wouldn't pour it this year anymore, unless is was an absolute necessity.

What is the big discouragement of wating until Spring at this point?


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## Canarywood1 (May 5, 2012)

stadry said:


> i think what's being said is concrete can be placed at any time of year (these birds argue about anything !),,, it just take more steps to place it correctly,,, i prefer cooler/cold weather placing rather than dead hot,,, enjoy your day



Yes your absolutely right, but it just irks me when people talk through their hat, about something they know nothing about, if they can't give a first hand answer, they should just keep their lip buttoned.


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## HDS (Jun 21, 2014)

jomama45 said:


> I'm probably the only guy here who pours residential concrete for a living in a cold climate like yours. I wouldn't pour it this year anymore, unless is was an absolute necessity.
> 
> What is the big discouragement of wating until Spring at this point?


The porch slopes back towards the house pretty bad, about 2" per 4 feet from the middle. It pools near the inside corner. There was a ground level deck with 2x4's running parallel to the house on the ground that kept water away. The deck had been off a few months now and don't like thinking of sitting through the winter with more rain and snow going towards the house.

I don't think they will pour now, so trying to come up with a temp fix until spring.

Here's my first try, getting rain tomorrow will see how it does.


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## HDS (Jun 21, 2014)

Thanks for the lively discussion, hadn't heard back from the contractor so I'm pretty sure we are waiting until the spring.


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## landfillwizard (Feb 21, 2014)

From what can see in the pictures, there was incomplete compaction of the base under the pad. Having been a construction inspector for 10 years, there are special conditions that must be met before the contractor could pour. Most of them have been addressed in this post.


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## gregzoll (Dec 25, 2006)

landfillwizard said:


> From what can see in the pictures, there was incomplete compaction of the base under the pad. Having been a construction inspector for 10 years, there are special conditions that must be met before the contractor could pour. Most of them have been addressed in this post.


Actually that comes from years of water getting under and washing the soil out.


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## stadry (Jun 20, 2009)

actually - no one really knows why but that never stopped anyone from guessing/posting,,, personally, i think 1 of the workers dropped his lunch & it got cover'd over w/conc thereby attracting conc worms,,, once they're under your conc, they eat the btm causing dropp'd slabs like we see here :vs_worry:


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## landfillwizard (Feb 21, 2014)

stadry, never thought of that. Could also be where they buried Jimmy Hoffa?


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## stadry (Jun 20, 2009)

nope, hoffa's either under giant stadium in the meadowlands OR fresh kill landfill on staten island,,, heard it in a caldwell, nj, deli


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## HDS (Jun 21, 2014)

Heard from the concrete contractor and if the weather holds out, they will start on Monday. 

Weather forecast shows no low lower than 36F but highs starting at 48F the next week. I'm assuming they know what they are doing.


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## jomama45 (Nov 13, 2008)

As long as it stays above freezing at night, there will be competent contractors pouring exterior flatwork. I would be yet (I did last week) if we dind't have floors to do in a few new homes. If you trust the contractor, I don't think you have much to worry about..........


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## HDS (Jun 21, 2014)

The contractor has been in the area for 20 years and my wife has had them do work on the house before. They plan on using rebar on 3' centers and pouring to 5". One thing they did say yesterday when they stopped by was they wanted to pin the patio to the foundation. We did have a lot of settling with the current patio and it was pinned, but when it settles 5+ inches, the pinning failed. I assume the new base with proper compaction should fix that issue. But not sure if in SW Ohio, pinning is needed.


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## gregzoll (Dec 25, 2006)

If the old patio was there when the house was built. Yes it could have settled from the fill after the house was built. In our area, they are using recycled Asphalt with a mix of Cinders from the power Plant as the base. It works better then rock.


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## joed (Mar 13, 2005)

Not sure about pinning a patio to the foundation. I have seen patio raise an lower with frost and that would be an issue if pinned to foundation. I saw one patio that was only stuck to the foundation, not pinned, lift a 1/2 crack in the brick veneer over the winter and settle back in the spring. I think it's better to let the patio float.


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## Canarywood1 (May 5, 2012)

I agree with joed, i wouldn't pin it.


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## jomama45 (Nov 13, 2008)

DON NOT let them pin it, it will only fail again, in one form or another. The foundation and exterior flatwork are completely differnet animals: the foundation has frost protection, and is stable regardless of the season, where as the patio is going to possibly fluctuate with the seasons.

This has been tried many times in the past, and it extreemly rare to see it turn out well. Usually, it just creates collatoral damage to the foundation. The choice is your's and your contractor's though, but if you think you're going to outsmart "Mother Nature" with a few pounds of rebar, I think you have a rude awakening coming your way.............


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## HDS (Jun 21, 2014)

I talked a bit more with the contractor and he said they put the rebar in at a downward angle which would allow it to move. I'm inclined to ask them to forego the rebar and just use an expansion joint material.


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## Msradell (Sep 1, 2011)

If he thinks putting rebar in a downward angle is a good idea tell him to have a civil engineer explain to you why that is and how it would help. Otherwise, I agree with your idea about forgoing the rebar.


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## HDS (Jun 21, 2014)

Here is exactly what he wrote in the email when I asked about pinning to the foundation and issues with frost heave. 



> Drilling into concrete foundation - usually we are more worried about the slab falling, but when we drill, we do it on an downward slant so that the slab can move slightly up and down.


I found this on concretenetwork.



> The only reason to consider knitting the two together would be to prevent the new slab from settling back toward the house, creating a drainage problem. I have heard of situations where rebar is installed in the new slab and allowed to slide in and out of greased holes drilled into the foundation. This allows the slab to move without causing cracks, while keeping it from settling toward the house. However, if the sidewalk is placed over a properly prepared and compacted subbase, there should be no settling problems and no reason to tie the slab and foundation together (see Subgrades and Subbases for Concrete Slabs).


The patio we are replacing was pinned to the foundation, but the pins only looked to be about 1" deep into the foundation and they all snapped. The current slab looks to have sunk at least 4-6 inches.

I think I'll give the county building department a call tomorrow and ask as well. This company has been around for quite a few years, and the only negative review I found on them was that they didn't call someone back for an estimate.


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## joed (Mar 13, 2005)

If he is concerned about the slab settling then the base is not good enough. The unstable soil needs to be removed and replaced with proper compacted fill.


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## stadry (Jun 20, 2009)

i agree ' NO TIE BARS ' - that's why there's expansion jnt material,,, just because he's done it doesn't mean its correct,,, totally the opposite, pinning a floating slab to a structure is NEVER recommended

another point - IF he's using rebar in a 5" slab, it must be placed in the center of the vert axis +/- 5% ( .2" ) on chairs to support its placement,,, otherwise its incorrect placement,,, 1 more thing, according to aci, ALL steel must be covered by 2" of conc - top AND bottom,,, that cannot happen in a 4" slab

i won't say your guy's cheating - just still a bit ignorant but there's a cure for that


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## HDS (Jun 21, 2014)

I talked with the crew today and they said they pour right up to the foundation and that it was to prevent water from getting back there. The expansion joint material, how thick should it be? Also, if they pin and pour directly to the foundation wall as their normal procedure, if I ask they not pin and put expansion joints in, would they need to change anything on their base material? Besides, sand, gravel etc...compaction that is.


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## stadry (Jun 20, 2009)

unless some of the exp jnt mtl is removed & the resultant space filled w/acceptable joint sealant in the conc/structure jnt, there will always be an opening for water intrusion albeit small,,, 1/2" is std thickness,,, that's rarely found on residential plans even drawn by architects in my experience,,, we usually find that detail only on fed/dot work

far's the base prep ? no, nothing changes from std base prep


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## HDS (Jun 21, 2014)

stadry said:


> unless some of the exp jnt mtl is removed & the resultant space filled w/acceptable joint sealant in the conc/structure jnt, there will always be an opening for water intrusion albeit small,,, 1/2" is std thickness,,, that's rarely found on residential plans even drawn by architects in my experience,,, we usually find that detail only on fed/dot work
> 
> far's the base prep ? no, nothing changes from std base prep




From what I've gathered from here and other research, in SW Ohio, Cincinnati, it is best practice to put in the fiber expansion joint against the foundation wall and not pin it? I emailed him and mentioned not pinning and using the expansion joints, but will be out later this afternoon to discuss more. It makes sense to me to do it that way, hate to come off as micromanaging though.


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## joed (Mar 13, 2005)

The patio should be sloped so that water flows away from the wall not towards it. The small amount of water that would enter any crack along the wall should not affect anything. 
If you have leaks in that area then dig and fix them first.


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## HDS (Jun 21, 2014)

joed said:


> The patio should be sloped so that water flows away from the wall not towards it. The small amount of water that would enter any crack along the wall should not affect anything.
> If you have leaks in that area then dig and fix them first.


We had one leak, but I think it was due to the tie rod going through the foundation wall. The biggest problem was the settling back towards the house and the cracked concrete. I have some pics I can share later, but three was just a bit of pea gravel down and some parts of the slab, even though it had rebar was maybe 3.5" thick. One section only had wire mesh and no rebar.

And don't get me started on the rim joist rot I've got to fix today too, bottom half of the rim joist and sill plate are rotted out where our door is.


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## Canarywood1 (May 5, 2012)

HDS said:


> I talked with the crew today and they said they pour right up to the foundation and that it was to prevent water from getting back there. The expansion joint material, how thick should it be? Also, if they pin and pour directly to the foundation wall as their normal procedure, if I ask they not pin and put expansion joints in, would they need to change anything on their base material? Besides, sand, gravel etc...compaction that is.




If it were mine i would want the base material to be all gravel or stone, no sand and it should be well compacted in 4 " lifts.


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## HDS (Jun 21, 2014)

They are bringing in the gravel now, I said sand but was mistaken. They would do the expansion joints but made a good argument for pinning. Said they've had no issues and stand behind their work. 

The other thing is they are sloping in two direction for the main (I have 30 in the pic, but it isn't 30 but 20), 20' x 12' section. The arrows aren't quite to scale, but it from left to right, I'd say it drops about 3 inches over that ~20'. I'd measure but they are working. When looking at the chalk line, you'll definitely be able to pick up the slope along the long axis due to the siding. 
Is that a reasonable thing they are doing and am over thinking this?


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## HDS (Jun 21, 2014)

Here are some shots from the forming and gravel, plus the slopes.


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## HDS (Jun 21, 2014)

Some of the old concrete wasn't very thick in places. Also damage to rim joist/band.


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## Msradell (Sep 1, 2011)

The slope that is shown by the chalk line in the 4th picture on the short section of wall looks like it's awful steep. For that shorter distance it shouldn't be more than 1/4" and probably even less. You certainly are going to be will set anything there to store with that much slope on it.


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## HDS (Jun 21, 2014)

Msradell said:


> The slope that is shown by the chalk line in the 4th picture on the short section of wall looks like it's awful steep. For that shorter distance it shouldn't be more than 1/4" and probably even less. You certainly are going to be will set anything there to store with that much slope on it.


I asked the owner about that in an email as the crew wasn't out yet this morning. About 7 feet to the right of that corner will be a landing pad for the door. So there will be an area where the water could pool up.


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## HDS (Jun 21, 2014)

The landing and the rounded section still need to be completed, but so far going better than my initial feelings. I may have done the drainage a bit different but this will work. 

The landing will be 3'x3' and will be jyst shy of 8 inches. I wanted to do half that with a step, but got vetoed by the wife. She doesn't want it sticking out the 46 to 48 inches to do the landing and the step.

Here are some pics.


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## jomama45 (Nov 13, 2008)

Looks good to me so far.

THe only thing i can add is that I'd consider making the platform/steps out of wood/composite decking/etc... as it's far easier to moddify later if the patio were to settle an inch or so/you get older and realize 8" steps are too high/your wife realizes you were right and it should have a landing/etc.....


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## HDS (Jun 21, 2014)

jomama45 said:


> Looks good to me so far.
> 
> THe only thing i can add is that I'd consider making the platform/steps out of wood/composite decking/etc... as it's far easier to moddify later if the patio were to settle an inch or so/you get older and realize 8" steps are too high/your wife realizes you were right and it should have a landing/etc.....


The weather had been great for the pour and it looks good. 

You are right about the landing though and in a bit of a pickle with it. They used 2x8s which puts the landing height at 7.25" and the landing to the bottom of the threshold at a height of about 8.25". Then throw in the .25" per foot slope, and your foot is hitting at 8.5" down. The funny thing is my wife who is 5'3" tall is ok with it, but me at 6'5" feels like I'm sorry of falling forward. Most likely because my stride is longer and takes my foot out further, thus lower. 

Tomorrow I'm going to lay some 1/2 plywood down on the landing and see how it feels walking out and up. 

The contractor will be out tomorrow or Saturday and we'll have to discuss it. Hate to see them tear out the landing and redo it for 1/2" in height though, but it isn't safe. And that to me was a quick short cut.

The wood / composite idea seems so much better though, but my wife doesn't think it'll look good. Could even leave the existing landing, build it up so there is only a 4" (rough estimate)drop to the landing, then a second 4" step. Could even widen the landing too. 

Live and learn! 

And thanks for the help and discussion.


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