Can house stem walls be poured in sections?

[Sedgehammer]

Here are the 2 offending items below. Now i know they can be, as one wood just cap the end and then continue, but I'm asking if it is something that is done and doesn't cause a flaw in the design of the building. Reason for asking is I'm short on enough 2x12's to build the stem wall complete. I have about 200' of 2x12s.

I'd pour the yellow first, then green. The orange doesn't get poured and the red is a gap for the pex tubing, as that room to the top is where my boiler goes

Calling @nybhh, @jmouton & @Don P and anyone else that has experience in this type of fun

Thanks



 

 

[mike_belben]

Thats a good question.  Hmm.


The boulder dam footing was poured in sections, akin to house-sized leggo blocks... has been up a while, holds back a big lake and hasnt blown apart yet.  So it can be done.


I would think that the compacted earth below has continuity, and if you put enough rebar to overcome any shearing forces in your end joints should that earth below decide to shift, that the rim segments you pour will remain interlocked.  Big slabs are poured like piano keys with dowels along their control jointing and they may crack but dont lift away from each other.


Im not a pro, just observations to consider.

[Sedgehammer]

@mike_belben it has a 16"x2' continues footing under it. everything you see has an at grade continues footing under it. This will be sitting on top of that and is tied to #5 rebar every 4' that sticks up from the footing below

[mike_belben]

I gotcha now, i have only heard the term knee wall for that type of construction and shoulda googled stem wall before replying.  I thought you were still on the footer work.

I dont know the answer.  I was around a segment of a very long loading dock getting repaired at the plant, and it was a splice of new concrete to old using a dowel interlock also.   Most relevant experience i can conjure up.  Probably not as ideal as continuous pour.  I will be interested to hear opinions on it. 

[Mike W]

There is no issues with segmenting the stem wall as long as there is adequate reinforcing that ties the two or multiple pours together, all concrete cracks, you just want to keep it from separating where it does to prevent heaving or shifting of the separate sections.

Been placing concrete for over 30 years and built too many homes to remember, some were necessary to form and pour in segments, non have had any issues, again its all just about tying it all together with adequate reinforcing.  pending the height of your stem wall, a single or two #5 bars would suffice for this.

[doc henderson]

It is nice to form it so it has a neat appearance and the next section can fill in.  i.e. not rough or angled.  some will add a 2x4 in the form to remove after set, and before the next section, to form a key.  in addition to rebar crossing the joint.  pouring the basement walls of my shop, we had a delay getting the last concrete, and had a cold joint.  bothered me at first, do not see it now.  OCD.

[Sedgehammer]

@doc henderson  :D :D :D I get accused of that and accused of that often....    in my defense, I just like it to be right..... ;D

@Mike W oh there's no shortage of rebar here. That's another accusation that I get accused of, but we have very few cracks and zero separations. Poured 100's of yards here alone. Most wood say to use 4 #4, I'll use 6 #5 or 4 #5 & 1 #8 or similar

There will be minimum of 2 #5

[mike_belben]

So burnt mattress wire reinforcement is out then?  

;D ;D ;D

[Sedgehammer]

Oh, umm, never thought of using rust. Let me think. Ok, I thought. I decline..... :D

[farmfromkansas]

So how tall is this stem wall? I have seen basements where they used 1x8's for the forms, with 2x4's framed up like walls on both sides, and some twisted wire or rods for ties.  Think you should block the wall off where it stops, with a 2x4 for a sort of keyway, drill holes for your rods, slide your boards over the reinforcement, and use screws to fasten.  You can much easier unscrew, than pull nails in forms.  Find that screws for all forms work great, may have to dig the concrete out of the screw ends, but if you start taking off your forms the day after pouring, it comes apart pretty well. I used to use plywood forms for stem walls, would start forming as soon as the footings started setting up, nailing my 2x4's down on the footings with plain 16d nails.  That way after you poured the stem wall, the nails pulled right out of the concrete. And it holds well.  Main thing is have some batter boards set up and everything marked so you can transfer your marks to your footings and not have to fool around squaring up on the footings.

[jmouton]

i always like to have a continuous pour ,, every time you stop ,, say with a form board you have a chance of leak from water, not a good bond even if you use rebar through the form,  most basement  walls around lower mich dont even put bar in them, dont know why,,  i would , but they are formed and poured all at once, even if we had a 100 -150 yd pour we will line trucks up and keep pouring ,,,those are some rough days .we use plywood or 2 bys for forms for something like that and use alot of jack bds, nothing screwed in concrete is as strong as something cast in it ,

[Ed_K]

 I poured my sugarhouse floor in sections, because I couldn't work very long in a days time do to being sick and not able to have someone else do it. Rita an I used bent bandsaw blade bent into z s on top of pieces of ledge to hold # 5 rebar every 16" in squares. The floor is 4"-5" thick and and most days we put down a section 6'x6' this was in the summer of 2019. So far there's no cracks from frost or expansion. You can see the start -stop but someday I will do a slurry pour to hide the lines

[Walnut Beast]

i always like to have a continuous pour ,, every time you stop ,, say with a form board you have a chance of leak from water, not a good bond even if you use rebar through the form,  most basement  walls around lower mich dont even put bar in them, dont know why,,  i would , but they are formed and poured all at once, even if we had a 100 -150 yd pour we will line trucks up and keep pouring ,,,those are some rough days .we use plywood or 2 bys for forms for something like that and use alot of jack bds, nothing screwed in concrete is as strong as something cast in it ,

Wow. That's interesting no rebar in basement walls. Around here the footings for basement have the vertical rebar in then you tie off your horizontals then set the pans sprayed with diesel. And a pour all at once. 

[Walnut Beast]

Sure a continuous pour is best but like any other concrete the existing rebar protruding through to next section or drilling and and adding rebar. On the basement wall your pouring on the footings 

[Sedgehammer]

@jmouton agreed, continous pour is best. With the said this is not a basement and we are above grade. All water drains away

I cannot wrap my mind around not using rebar in a basement wall and how that passes code

@Walnut Beast we are also pouring on top of the footing, so it's not different in that regard. 

I'd like to pour continously, but not paying $85+ for 2x12s that won't get used again till we do the house build

[sidehill6]

poured literally thousands of yds of concrete working for a contractor doing bridge work for new york dot, construction joints are a fact of life in bridge construction, rebar running thru the joints, keyways for shear movement etc. if water is a consideration there are all kinds of waterstop products to pour in the joint, some visible some not.

[farmfromkansas]

Price of lumber will come down as soon as the big mills get to running at capacity.  Local board of trade guy said a week ago the futures were down. Then it will be some other shortage, probably cement or something else. Been hearing windows were in short supply, and wiring is up 5 times before covid levels.