Filled Cinder Block or Poured Cement stem walls?

[bren5270]

So Ive been looking at the best/easiest/cheapest way of doing the stem walls (5ft) and since Ill be doing it largely myself, Im curious if a block wall (completely filled with cement) really is cheaper/easier than poured walls?

With the work to lay a cinder block wall, and hand mix/apply mortar, making sure to get the blocks correctly positioned, then having a pump truck come in and fill them.
vs
buying some 2x4s and plywood, building up sets, and having the pump truck come in and fill them.


Just strikes me as poured walls being easier and once factoring in labor for the block wall...?

 

[ishiboo]

Probably a horse a piece. I'd say concrete was the easier route.

If this is a smaller wall, also think about going with ICF blocks.

 

[readhead]

A lot more than plywood and 2x4 involved in forms. Consider renting the forms and parts if you go that way. Block is not as DIY as you might think. ICF may be the best choice for you . More DIY friendly.

 

[sberry]

Isnt this low enough to pour from a truck? I doubt every core needs fill in a short wall.

 

[DougWil]

Isnt this low enough to pour from a truck? I doubt every core needs fill in a short wall.

Every cell below grade, that would be all in stem wall need to be grout filled.
Otherwise they fill with water, freeze and break the wall apart.


Additionally CMU walls have a far lower capacity for holdowns than concrete.

 

[kbs2244]

The question is the side pressure.

Is it back filled on both sides.
What kind of soil.
How well drained.

At the least you will need the wire grids placed between each layer of block.

 

[sberry]

Every cell below grade, that would be all in stem wall need to be grout filled.
Otherwise they fill with water, freeze and break the wall apart.


Additionally CMU walls have a far lower capacity for holdowns than concrete.

Yes, spose so if its filled both sides.

 

[Orionrising]

Yes, spose so if its filled both sides.

Another thing you can look at is surface bonding drystacked blocks.

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[sberry]

How strong we figure this has to be?

 

[bren5270]

It'd be pretty difficult to do straight from the pour truck into the blocks, especially access wise.

Good to know about filling below grade blocks. weird that the inspector didnt mention that, I was thinking of only filling the ones with rebar in it instead of completely filling all the cores, but im worried about having enough strength and also keeping the cement in the right blocks (I guess wadded up news paper is supposed to be enough to hold the cement?)

Strong enough for a 2 story garage (apt above) and in a flood zone.

The inspector wants me to use threaded rod instead of rebar and run it all the way from the footer to the mudsill (so Ill need 6-8ft threaded rods and have to place the blocks working with those ...sounds like an odd way of doing things but maybe its due to the floodzone?

the inspector wants me to run threaded

 

[Orionrising]

Depends on even vs uneven soil loading. And what's on top of the stem wall. Either way rebar etc is likely needed.

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[theoldwizard1]

The proper blocks can be dry stacked with locking pins. I don't know the cost.

Without a proper foundation and proper drainage BEHIND THE WALL, it is a guaranteed failure !

 

[rburke65]

Rent the forms and fill with concrete.

 

[larry4406]

I'm a poured concrete fan myself.

Block is yesterday's technology today as far as I'm concerned. It's porous, cracks along bed and **** joints. YMMV.

 

[DougWil]

The inspector wants me to use threaded rod instead of rebar and run it all the way from the footer to the mudsill (so Ill need 6-8ft threaded rods and have to place the blocks working with those ...sounds like an odd way of doing things but maybe its due to the floodzone?

I think what he wants is your holdown anchors, and possibly mudsill anchors to to be anchored all the way down to the concrete footing, not just in the CMU cell with a short anchor bolt.
Probably with a large washer and nut on each side.

Holdowns are far stronger anchored this way, especially at corners.

 

[sberry]

Center of wall in big flats really needs the power.

 

[Dr Stan]

Steel reinforced poured concrete should be much stronger than block. While you're at it have the concrete company add fiberglass to the mix.

+1 on renting the forms as they will result in a much more uniform therefore stronger pour than stick built forms.

Happy building.

 

[DougWil]

Steel reinforced poured concrete should be much stronger than block. While you're at it have the concrete company add fiberglass to the mix.

+1 on renting the forms as they will result in a much more uniform therefore stronger pour than stick built forms.

Happy building.

Fibermesh (not fiberglass) adds nothing to the concrete strength all advert hype aside.

It does help reduce water migration and secondary shrinkage cracking. In a 5" square grout cell water migration and shrinkage cracking are non issues.

 

[padroo]

I am a block fan from the old school. With propper footings with drainage, wire reinforced every third course, pilasters if needed. Rebar and fill the corners and pilasters there would be no problem.

If this is a do it yourself project and you have never laid block I would hire it done. I worked as a laborer for
The bricklayer when I was young and was able to build my 32 X 40 garage completely out of block and my 36 X 90 house basement. It is what you are more comfortable with.

 

[bren5270]

I think what he wants is your holdown anchors, and possibly mudsill anchors to to be anchored all the way down to the concrete footing, not just in the CMU cell with a short anchor bolt.
Probably with a large washer and nut on each side.

Thats EXACTLY what he wants, almost word for word

Rent the forms and fill with concrete.

I would but nobody around who rents forms ...least not that I know of

Depends on even vs uneven soil loading. And what's on top of the stem wall. Either way rebar etc is likely needed.

The inside will have about a 3 to 4 ft infill and slab on top, so yeah, uneven loading, 2 story garage apartment on top. Yeah definitely needs rebar/threaded rod.

Steel reinforced poured concrete should be much stronger than block. While you're at it have the concrete company add fiberglass to the mix.

+1 on renting the forms as they will result in a much more uniform therefore stronger pour than stick built forms.

Happy building.

Yeah I know its going to be stronger, Im looking at cost/ease.

 

[bren5270]

So after doing some additional research, it looks like building forms may actually be more work than the block wall (once I factor in not renting them, adding center ties, wasted wood costs, etc).

Anyone ever look up how much more it costs to have a mason lay a block wall vs doing it yourself?

 

[DougWil]

1st off where are you?

2nd, it obviously is permitted, but is this an engineered design?
Who determined footing size and depth?
If an engineer, is he OK with you choosing various methods, instead of following the plans?

A good mason and crew makes laying block look very easy and fast.
It isn't if you have never done it. What is your time poking along and learning worth?

Concrete, CMU and IFC are all good options depending on your ability, able to rent forms, local help etc... none are vastly cheaper or easier than the other.

 

[Chris705]

Regarding the need to use continuous lengths of threaded rod, I would approach your inspector and question that...bent #5 dowels coming out of the poured footing and then lapping/tying vertical rebar say by 12" and then lapping/tying anchor bolts another 12" at the top of the vertical bars will result in a continuous path of reinforcing & hold down capability. THe proper overlap is something like 20 diameters of the reinforcing dia used. This is common, continuous threaded rod may make the inspectors life easier for a DYIer but will make your life miserable if you have to lay block over the rods....a properly drawn section detail to present to your inspector would probably help here once you decide which way to proceed on the wall construction.

 

[PWC Repair]

Went back and forth a lot with this myself. Will you be backfilling? If yes, I'd say poured concrete with rebar. I decided that my foundation was not the place to try and skimp to save a buck. Since my building will be standing on the wall I didn't want any chance of problems in the future. What would you do?? Tear the building down to fix an issue??

 

[DougWil]

Regarding the need to use continuous lengths of threaded rod, I would approach your inspector and question that...bent #5 dowels coming out of the poured footing and then lapping/tying vertical rebar say by 12" and then lapping/tying anchor bolts another 12" at the top of the vertical bars will result in a continuous path of reinforcing & hold down capability. THe proper overlap is something like 20 diameters of the reinforcing dia used.

Code min is 40 bar diameters, 25 inches for #5 bars.
You wouldn't get that out of a 12" smooth anchor bolt.
http://ncma-br.org/pdfs/68/TEK 12-06A1.pdf

That is why the continuous threaded rod embedded in the concrete footing.

 

[bren5270]

Code min is 40 bar diameters, 25 inches for #5 bars.
You wouldn't get that out of a 12" smooth anchor bolt.
http://ncma-br.org/pdfs/68/TEK 12-06A1.pdf

That is why the continuous threaded rod embedded in the concrete footing.

Thanks everyone for all the responses! This forum sure is helpful!

Thanks Doug, thats exactly what he said. He said I could alternatively put Rebar with bent bottoms (I think it was either 6" or 7" bottoms) running vertically the length of the block wall (6' on center) then the anchor bolts would have to be installed 24" overlapping with a nut and washer on the bottom.. at that rate threaded continuous rod from the base is just easier.

Engineering wise my footer is actually going to be larger than the plans (plans call for 18" mine will be 24"), and both foundations are based on the nc code / inspectors 2 options he gave me for stem walls.

Yeah I was going to fill the blocks, however I havent decided whether I am going to completely fill the entire wall or if Im just going to fill the parts with rebar...

 

[LX-Markham]

The inside will have about a 3 to 4 ft infill and slab on top, so yeah, uneven loading, 2 story garage apartment on top. Yeah definitely needs rebar/threaded rod.

Finished interior slab to finished exterior grade is a 4' difference? I would definitely go with reinforced concrete. I would also install bent dowels from the wall into the slab.

Was there a permit drawing for this? These details should be on the drawings.

 

[Chris705]

Very interesting read on the link Doug (thanks)...I am familiar with the masonry TEK notes, always educational, it was in these notes that I read a few years ago about dry stacking block and then parging them with a structural foundation coat. I thought that could be a way I was going to proceed as I had never laid block before. Then I was planning on grouting cores solid. Ended up with a mason.
Interesting how with every code year they seem to constantly tweak the requirements for reinforcing splices. I hadn't imagined the bars and anchor bolts not being tied together as is allowed, as long as the overlap is 40d then all is good, that just seems like a lot compared to what I am used to seeing. I just can't imagine the length of all-thread sticking out of a footing....there will need to be some sort of anchoring put in place to hold everything in place for the pour.....

 

[bren5270]

I have a plan drawing but the Stem wall isnt as tall, its 2 courses, Ill have a 5 possibly 6 course wall depending on what the inspector comes back with regarding the flood elevation certificate. At this point my plan is to fill the blocks with the threaded rod and one on either side of it.

 

[RobSmith]

Google DINCEL wall systems you will be inspired .

 

[jav]

I went through this decision and the CMU foundation walls were MUCH cheaper than poured... so that's what i did. I did fully grout all the cavities. I'm generally happy with my choice and feel it is perfectly sufficient for my need BUT I believe a poured wall would better/stronger/longer lasting.

My only complaint so far is that the block telegraph moisture much more so than a poured wall does. I plan to seal mine as soon as it gets warm enough.

Just as a point of reference- I did most of it myself but had a mason friend lay the block. It cost me less in material and labor for the CMU foundation than just the forms guys wanted to setup- pour- strip the forms (no concrete).

 

[pcmeiners]

I have done both block and poured wall numerous times. Block might look easier but done correctly it is a lot of work. A pumper to fill block?, no way. You need to fill every course before moving on to the next one or you end up with partially filled blocks, unless you are pumping cement which is watered down resulting in weak strength. With the quality of the cinder block today, there is no way you will produce a water proof wall, for a high quality wall you really need cement blocks.
Overall, building the forms for poured concrete is less work, but if not done correctly you could easily have the concrete burst the forms....you can not skimp on the reinforcement of the forms.

 

[xyster101]

I did a 7 ft tall 12" CMU wall filled. I did wire grid every 2 layers and put rebar every 4 ft around. Wall is 3 sided 24x24x24 ft. It was a LOT of work. I worked with Father in law. I mixed mortar, he laid most of it. Then cleaned up the joints. Applied water proof plaster and then tar on the outside.
It really is all about drainage to keep your wall safe. Poured is stronger but will probably cost more.
CMU is cheaper material but more in labor. You can diy but a lot of time.
We poured the cement into a bucket on a tractor and then dumped it in the wall. Did 4 yards in 45 min. Only had to pay for 15 min extra unloading time.



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[bren5270]

I did a 7 ft tall 12" CMU wall filled. I did wire grid every 2 layers and put rebar every 4 ft around. Wall is 3 sided 24x24x24 ft. It was a LOT of work. I worked with Father in law. I mixed mortar, he laid most of it. Then cleaned up the joints. Applied water proof plaster and then tar on the outside.
It really is all about drainage to keep your wall safe. Poured is stronger but will probably cost more.
CMU is cheaper material but more in labor. You can diy but a lot of time.
We poured the cement into a bucket on a tractor and then dumped it in the wall. Did 4 yards in 45 min. Only had to pay for 15 min extra unloading time.
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Awesome, good to know.
how long did it take you?
so did you actually fill all of the blocks then?
when you say wire every 2 layers, what do you mean?

 

[Hilltopmasonry]

Bren,

Wire is used in masonry walls. Called block lock or ladder wire. You put the wire down before you spread the mortar for the bed joints and it basically reinforcing wire.

You fill block walls with GROUT not concrete


Here is wire tying an outer brick wall with cinder block




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[xyster101]

Every two layers of cement block I put wire. The wire can be bought from the block company. They deliver it on a truck and drop it off with a crane.



Then it helps to have one person mixing the mortar while the other person lays the block and switching as the blocks are heavy. I did 12" CMU here at 60 lbs each!



I then applied water proof mortar stuff to the outside. Some kind of plaster material. Once that dried I added tar. I also had 4" drain tile all around the base.



Here we mounted a large metal mixing pan to a skid and put it on the forks of a tractor. The cement truck would dump the cement into the bucket thing and we would pour it into the top of the wall. Basically filling every part of the back wall and 10 ft out on both sides. There was also a piece of 5/8" rebar every 4 feet dropped into the wall before we filled it. Instead of a tractor set up, many cement places have a convory truck that can lift the cement. Or you can rent a pump truck, but that is like $600 for a few hours. With the 5 yards of concrete the truck bought we were given 30 min to unload and it took us 45. So we had to pay like $50 extra or something for the time.



You can see the wooden funnel box sitting on top of the wall to aid in getting the concrete into the wall cavity without spilling it all over.




If you want to see more check out the build thread I made:
http://www.garagejournal.com/forum/showthread.php?t=212873

 

[bren5270]

Ahhh ok I see now, I had a feeling that's what he was referring to.

Xyster, did you fill all of the blocks with cement or just ones with rebar?

Wow that's impressive. Any reason you didn't use a pump truck though? sounds like that would've been easier than the tractor dumping method?

 

[BADSIX]

I would think the insulated foam block forms would be the way to go, easy to work with. my neighbor built a 2 story house with them, looked easy and he was done with the walls in about 2 weeks
Jay D. .

 

[gnpenning]

I would think the insulated foam block forms would be the way to go, easy to work with. my neighbor built a 2 story house with them, looked easy and he was done with the walls in about 2 weeks
Jay D. .

I agree. Much lighter than block and faster to install. He could even go all the way up or just the first floor. Shouldn't need the threaded rod either if you go all the way up.

Many have no experience with ICF or know anyone that does so they stay away. To bad. I did my home basement and main floor with ICF and love the comfort and sound level. I was able to buy all the block and bar for both floors for what it would have cost me to have someone do my basement wall alone.

Most who are against it have never used it and the ones that did and don't like it didn't brace it proper before the pour. The rest Love it and keep using ICF and singing it's praises.

 

[Milton Shaw]

I used 12" split face blocks with 2 pieces of rebar every third course, then #4 in every core and then filled with 3000 lbs mix and used a long shaft ******** to make sure it gets all the way to the bottom. I made a metal chute to fit two cores and poured directly from a bobcat concrete mixer attachment. The finish wall was 10' high at the high end to about 6 foot at the low end. No cracks in it or any other retaining wall I have done this way. I learned my lesson on a wall 45 years ago and have done them right since then.