So, my pole barn/garage/shop is going up this week...finally.

It should be done by Friday and I'm having the plumber come to do the rough in stuff this weekend. I was planning on having the builders pour the pad inside once this was done, but now they are telling me that they can't pour until the spring because our night temps are supposed to drop into the 20s next week and beyond.

Does this sound right if pouring inside an enclosed garage? I understand that you don't want it to freeze, but I would think that if I can get the heater going in there for a few days while it cures that we'd be alright to pour? They use curing blankets to pour outside in the winter, couldn't they be used inside as well?

Should I just resign myself to the fact that I'll have to wait until spring to get this done?

We went through this with concrete jobs last month. One absolute no-go has to do with the soil temperature. If the ground is frozen, as I understand it, the concrete will not cure, and once the normal chemical process is arrested by the temperature, the mix will never develop the intended strength.

I was told the reaction is exothermic for the first 24 hours. The danger comes after the first day, when the internal heat goes away, and the ambient temperature governs.

Hopefully an expert will come along and give you more information.

I usually figure that I can pour foundations up to about Christmas in the Chicago area. Bear in mind that these are pump, vessel and pipe support type foundations that are engineered and go down to frost line. My projects sometimes involves slabs also. Being in an industrial settings, there is usually plenty of steam around so I have the contractor wrap steam hoses around the foundations and everything is covered with insulating blankets.

If you already have the walls up and can seal the openings so you can maintain a reasonable interior temperature, say 50F, you may be alright. 20F is pretty cold. Your biggest concern will be the perimeter of the building where the slab could be exposed to the outside temperature. Here is where the insulating blankets would come in handy. Check with a contractor that does more industrial type work, they may be more experience with pouring in cold weather.

There are additives that can be added to the mix when pouring during colder weather. Your contractor should know the proper usage and what care needs to be done after the pour is completed.

Couple of things to think about, Gustofer:

-- Think about putting the job off until spring. Seriously.

-- If you just cannot wait until you won't freeze the concrete, then INSIST that whoever you have placing the concrete do the following:

Tent the entire area

Place heaters in the tent, and make sure the heater exhaust is vented outside the tent (not just to avoid hurting anybody with carbon monoxide, but because the exhaust will make the concrete surface funky)

Put thermometers at several locations in the underlayment and hung in the air inside the tent

Actively monitor the temperature and record it

If your concrete freezes before it's cured, it's worthless. You'll have to re-do the whole placement that freezes.

Seriously, think real hard about putting the job off until next April or May.

Thanks,

Sap

quote:

Originally posted by Gustofer:
Should I just resign myself to the fact that I'll have to wait until spring to get this done?

Yes.

They add antifreeze chemicals to the concrete around here when the temps drop.

Montana, right? Big Sky Country?

Here in Philly guys pour nearly all winter through. Nearly, but not quite. Our water services have to be 3' deep.

A buddy in Gardiner MT told me in the '90s that they put their water services 7' deep.

So I'm no use to you. But I do recall I awoke to a 33˚ dawn this past Memorial Day Weekend in Yellowstone.

Sounds pretty cold for concrete.

quote:

Originally posted by SapperSteel:
Seriously, think real hard about putting the job off until next April or May.

quote:

Originally posted by DMF:
Yes

After sleeping on it, I think you guys are likely right.

My problem (and always has been) is that when I finally decide to do something or to have something, I want it now. Patience is a virtue that I lack. The other issue is that I have some framing and building to do inside that I can't do until the floor is in and I really don't want to wait until next spring to get that done. Dangit!

I guess that I don't really understand how the stuff works. They're putting up a new building in front of our hospital here right now and pouring forms and such outside. I'm sure they'll also be pouring the slab...outside. How is it that that can be done, but mine can't when it's inside a heated building?

Oh well, at least the thing will be built and (mostly) usable for the winter.

I've seen them pour inside concrete in the wintertime here in S.E. Michigan, but they run multiple big-ass space heaters for days and days afterwards.

quote:

Originally posted by ensigmatic:
I've seen them pour inside concrete in the wintertime here in S.E. Michigan, but they run multiple big-ass space heaters for days and days afterwards.

I'm putting in a 60K BTU propane heater in there (hopefully) next week. I'd sure think that that would easily keep it up to 50F+ without any trouble for the week or so required.

I don't know. I'd just hate to have it screwed up and then have the cost and trouble of re-doing it to deal with.

quote:

Originally posted by Gustofer:
I'm putting in a 60K BTU propane heater in there (hopefully) next week. I'd sure think that that would easily keep it up to 50F+ without any trouble for the week or so required.

All the way down to the dirt under the concrete? All the way out to the edges?

That seems to me unlikely.

How much is this venture costing you? Is getting it done now really worth the chance of mucking it up forever or having to do a costly do-over?

ISTM if it goes wrong you're probably on the hook for the results, regardless of whether the contractor or the weather's at fault, being as the contractor has already given themselves an out.

I've got a man cave I'm building in a corner of the basement. It should have been done by now. Except there was first this one thing that got in the way. Then this other thing. Both requiring I wait on contractors. (Top-to-bottom basement wall crack and custom HVAC duct work.)

*shrug* I'd like it to be done, but it is what it is.

Anything can be done If you want to pay for it.

My son is in the construction business . It can be done . Consult an actual contractor and get his take on it .

The specs. I have always seew said 40 degrees and rising.

I do this for a living. The only real concern is substrate temperature. It needs to be above freezing. 24 hours is the outside window and it seems like your contractor is playing it safe, which is a good thing.
My suggestion is to find a day that will be warm and get the job done.
You could also use a fast setting concrete bag mix that has an endothermic reaction and actually heats itself from the inside. We use Basf 1060 or 1061 but it’s expensive. Our price as a bulk purchaser is $1000/yard. Plus labor. It’s a pain in the ass to do larger areas but yields an 18,000psi strength and is traffic ready in 3 hours. 6 hours to full cure.
Any questions feel free to email me.

quote:

Originally posted by Gustofer:

quote:

Originally posted by ensigmatic:
I've seen them pour inside concrete in the wintertime here in S.E. Michigan, but they run multiple big-ass space heaters for days and days afterwards.

I'm putting in a 60K BTU propane heater in there (hopefully) next week. I'd sure think that that would easily keep it up to 50F+ without any trouble for the week or so required.

I don't know. I'd just hate to have it screwed up and then have the cost and trouble of re-doing it to deal with.

Don't do it.

It's the ground temp they're worried about. This is something where you don't want to have to redo it. If the air is heated, it may cure on the top, but never cure on the bottom.....and then crack everywhere.

Well, the builder just got here for the day and we were talking about it. He doesn't think there'll be a problem, provided I can heat up the inside (which I can do). He says the only real concern would be the edges and that can be solved by using some foam board around the edge of the building and down about 4 inches into the gravel. He says that I'd be just fine doing that.

I'll have to think it over some more now.

I'm not a concrete authority.
I do know from living in Western NY that you could tell the houses that poured concrete in low temps for foundations/driveways/etc.

Pretty much standard for those borderline/sub-freezing pours was cracking, porosity, flaking away of surface areas and poor weathering. It becomes clearly visible after a few years.

I know it's frustrating but it's probably for the best if you wait until warmer weather- there are folks on here and around who know how to do it correctly in early cold weather, but it does cost more.

If your contractor is experienced and thinks he can do it, you run the heater for days before, and he has edges figured out, that's different than pouring a slab on bare ground without heat.

Maybe in a week things could warm up a bit long enough to get it done?