When to pour the basement slab?

Erin · August 19, 2009, 10:31:47 AM

I know our options are basically to pour before erection of walls (we're doing block, btw) or at any point after we start getting further along in the construction.
At this point, we're planning on doing the slab ourselves, but I want to get the basement walls up and hopefully the house skeleton so we can get the house framed by Christmas. Should we take time to lay the slab? Or should we wait until later?

What are the pros and cons of either option?

MountainDon · August 19, 2009, 02:52:04 PM

If time was a crunch factor for me I would get to work on the foundation/basement walls and get on with the rest of the building. As you stated you can pour the floor anytime later. Leaving the pouring till after the rest of the building is up would allow you some time to leave the floor sit there nice and wet so it cures strongest. Twenty eight days to maximum strength if kept wet/damp so the chemical curing can continue.

As for downsides doing the pour later, one would be that any equipment that needs to be installed on the concrete floor could not be installed until after the floor was done. Furnace? Water heater... ?

August 19, 2009, 03:00:29 PM

I know on my place I waited until I had a roof on before I poured the slab. I loved the fact that I didn't need to worry about the weather (neither rain nor heat to concern myself with).

Since I used a pumper, the lines had to be hauled around a bit more, but it wasn't a big deal.

mt

Erin · August 20, 2009, 06:24:22 PM

Maybe that's the direction we'll go then. Just wait til we have a little more up before spending time, money and effort on the slab...
Since half of it is going to be a garage, I already know the chute will reach clear to the back corner. The other half, we might have to run a few loads with a wheel barrow, but I think it'll be worth it to wait a while.
Besides, we're still not sure whether to do radiant heat in the slab or not...

rocking23nf · August 21, 2009, 09:12:02 AM

most large concrete companys have large pump trucks now, that have basically a large arm on it that can reach up 4-5 stories or more. So they just stick the hose in your window and pump away.

August 21, 2009, 09:44:46 AM

I'm gonna take a guess that you don't live in rural, western Kansas.

There is no such thing as a "large concrete company."
Not to mention, there is no reason anyone would have a chute to reach up 4-5 stories...

rocking23nf · August 21, 2009, 11:20:52 AM

LOL I wouldnt even be able to find Kansas on a map.

Don_P · August 21, 2009, 03:51:50 PM

All depending on the amount of unbalanced fill and the characteristics of it, if you backfill, having the slab down there sooner rather than later helps brace the walls.

countryborn · August 28, 2009, 01:29:46 PM

We have the same question - when to pour the basement slab? we will have the waste drain under the slab, of course, & we are planning to use radiant heat. placing all that tubing will take time.
but we have already done most of the backfill, dirt is 6.5 feet up the east wall. west side, you can walk out, we are on a hill with about 23% grade. clay soil.
foundation & basement walls were poured about 3 years ago, so well cured, & concrete is 8 inches thick. but I am concerned about the pressure of all that dirt in our wet winter. thinking maybe we should focus on getting that slab down before wet winter weather? we are in Western Oregon.

rick91351 · August 28, 2009, 11:46:36 PM

As ex-ready mix truck driver I seen a lot of mistakes. I really like Don_P's advise. I hate to see anyone take a chance. However at three years your walls are as cured as they ever will be. 8" is plenty thick - so you should be okay. If you do not pump watch out if you have to get cement trucks close to that wall. More than one wanted to bury itself in a back filled clearance. Not really the drivers fault nor the finisher; it can look very firm and settled yet there is just no compaction to the soil underneath.