bronson7

Curious as to why the concrete slab floor was poured first. Generally, is not the floor poured later?

Raven 666

No raft slab construction method ,,,slab and footings first then standing of frames and construction of the structure ...once frame is erected external finishes applied bricks , cladding , roof sheets etc ,,,once exterior is water tight move into the inside and install internal finishes ,plumbing ,electrical wall and ceiling linings ,,,doors etc Australian building technics may be different to North America but I am sure the principals are similar

doubleurx

It's much easier to pour the slab first. It gives you a nice flat surface to frame the walls. This is common here in the US also.

Mussl Kar

Depends where you live. Northern states pour a footing about 4 feet below grade, foundation wall on top of that extending at least 18 inches above finish grade. Footing needs to be below winter frost line to stay intact.
I have a 6 foot concrete apron a my garage entrance and it has 1 inch of pitch draining away. Not some winters though. Frost has pitched it back once, causing a winter rain to form a big puddle near my garage door on the inside. I am glad I made it 6 inches thick with plenty of rebar in it.

FFaust

Now facing MY slab/floor decision:

We are now down to freezing temps for a week, and maybe for the rest of winter, and need to decide on whether or not to pour floor now or in the spring.

Back-filling today and one concrete guy is ready to pour, while another says that I should wait til May (maybe he's just too buys to do it now?). Thoughts?

Will be 6' + combination of rebar and wire mesh.

bronson7

^^^ If it were me and you're not in too much of a hurry, I would wait until Spring time. It will allow more time for your backfill areas to settle nicely and no fear of not curing the cement properly. Just my .02

FFaust

Fully agree, but it would be soooo nice to have a finished floor, lol.

FJSeattle

You can pour concrete under water (the Romans invented it)

Go for it if you get a couple good warm days...

Nizer

+1 My garage floor was poured in the winter. Sub-zero temps, straw piled up around the foundation, industrial propane heaters inside. Yeah, they can pour almost anywhere anytime but I wished I'd waited as I don't think the pour was as good as it could've been.

doubleurx

Sorry, yes foundations and stem walls are always done first, then slab, then frame. I lived in MA for 25 years and now in CA at elevation......same techniques on both coasts, except our frost line is only 24" here near Tahoe.

The key to not getting heaving is the prep and drainage.

HeyJacu

Any concrete work below 40 degrees F requires special attention whether it be the use of admixtures, the use of hot water in the mix, heating the space to 40 degrees for 24hrs, thermal blankets... in the US I recommend referring to the concrete institute's standards especially if you get close to this temperature. Don't let anyone convince you that nothing special is needed if you drop below this temp before or during curing of the concrete mix occurs.

To address differential settlement, especially at thresholds, have your subcontractor thicken or turn down the exterior concrete slab where it meets your building entrance and dowel it to the foundation. This will help maintain the inside and outside slabs at the same height no mater the temperature. This connection has to be detailed correctly but is very important to consider, imo. It won't work of course if your base materials don't meet the requirements for your part of the world; minimum thicknesses, compaction of the native material, etc.

osu s2k

^listen to this man, lots of work and energy to pour and cannot guarantee it will be as good. Dry it in Let back fill settle. Lay down nice gravel and have them tamp it down. You can use it just fine and gives it more time to settle.

We poured a barn proprietary mix 2 slump with fiber and cured under water for 30 days 12 years ago and have yet to see a single crack.

FFaust

What does that mean?

Tamped pretty hard with this remote-control vibrator.

osu s2k

We Tampedthe gravel down one time when we didn't want to pour in the winter,,, we just had a simple hand walk behind compactor and it did a great job for five passes over the whole thing it was rocksolid no pun intended, the concrete description was just contractor talk for pouring good concrete under the best conditions and then curing under the best conditions. I'm not a concrete expert but I've read enough to know that the curing process is one of the more critical steps.... so point is for me if I was building in the winter where subfreezing temperatures are possibility, I would just pour down some nice gravel smooth it out compacted and deal with it when the weather improves…… This also will give the homeowner opportunity to decide if they would like to do colored concrete, or if they want to grind the concrete down and then the aggregate May actually be different

RobbieRob

You could still build the garage without pouring the floor/slab now and wait till spring to pour it. The garage would be up and water tight and then all you have to do is pour come spring time, that's how I did mine, built it first then poured after it was up.