Building a small addition, about 25 linear feet of foundation and wall. The problem I have is that the location is on the back of the building. Will need to bring in a concrete pump truck for each pour. The current plan is to have a 24 in footing and a 10 inch wall, frost depth is four ft.
I am thinking of forming the footing and the wall at the same time and pouring both in one pour. Basically 2x 12 on edges for the footing, 2×8’s on the flat supportted by some rebar to form the top of the footing and then the wall forms above that.
Has anyone else tried doing this? Am I missing anything?
Replies
Sounds like you're about 3 cy of concrete, that's a pretty premium for a pumper truck in my area. Why don't you sakrete it in a mixer? you can get a 1/3 cy mixer and run through about 3 pallets of sakrete @ $3/bag or so x 44 bags/ pallet. Get the fiber reinforced if you're concerned about no large aggregates. That would get around your doing it all in one. I think the problem is no compaction / can't visually see voids and no way to make sure the concrete fills to the top of your footers, i.e. the load is spread over the whole volume of footer but if you do it as described you will have voids removing volume.
remodeler
The small mixer is of course my other choice, I don't relish the idea of moving all those bags!
The void problem crossed my mind, but it really is much different than those bigfoot forms used at the bottom of sono-tubes. They don't seem to have a problem with voids.
It would be hard to ensure the concrete gets into the upper corners, but I am not sure that the corner is necessary for strength anyways.
Still thinking about trying it.
if you have the soil bearing capacity, some jurisdictions allow a 12" wall with no footing..
about half the time that is what we pour.. just depends on which form company we useMike Smith Rhode Island : Design / Build / Repair / Restore
Around here we have a third choice. These companies sell it mixed in a big mixer and you just hitch it up to your pickup and drive home (slowly). Wheelbarrow work then begins (you need a lot of labor for this approach). This won't work if you are too far away from the guys that do this and need to make several trips. As I recall, we could tow about a yard at a time with our truck.
Until a couple of years ago the local lumber yard had one of those trailers. But they stopped, unfortunately.
The 12" wall with no footings has some possibilities, but I won't know till I start digging.
I guess from all the alternative ideas no one likes mine.
Still wondering why it wouldn't work??
Put enough effort into the set-up & pour and it almost certainly would work. The question to me is whether or not it would work better/faster/cheaper. My guess is, with a small job like this, you could do it faster and more reliably with bags & a mixer. When all is said and done, it might not be that much more work either.
you can rent a concrete vibrator to solve the void problem, they work very well.
we paid about 35.00 a day for one
It's pretty common to pour footing and stemwall simultaneously here (West Coast).
Form your footing. Nail 2 X 2 or even 1 X 2 spreaders across the top of your footing form boards on 2' to 4' centers and on corners.
Build your wall form by cleating the bottom of the form to the spreaders. Pour concrete with the pump, pouring the footing as a lift, then pour your wall. With your 10" wall you should be able to do it in one pass if you keep the mud a little stiff.
We do the same process on taller walls, but you have to pour in lifts so the hydraulic pressure doesn't push mud out the top of the footing form but steady enough so you don't get cold joints.
You'll end up with remnants of the spreaders in the base of your wall, but inspectors allow it here on residential and I've seen a slew of nice construction with no repercussions.
This process does not work well with trench footings although it is do-able.
Those "U-cart" cement things, in my view, are a way of transporting concrete in such a way as to settle the aggregate to the bottom of the mix...especially if you have far to drive. Not a good choice IMO for a foundation wall pour.
Jules Quaver for President 2004
Edited 2/7/2003 9:06:28 PM ET by Notchman
For such a small addition, why not use a PWF foundation, Toolin?
Yes you can pour both at the same time but I don't recommend using a pumper truck because your slump is to high. Your forms will lift. When I poured my foundation which is 4' high with a 16" footing I poured a layer in the bottom just enough to fill the footing and and about 1/4 the way up the form with about a 3 to 4" slump. I poured the entire foundation and let it sit. Then I went back and filled it the rest of the way vibrating only slightly into the first layer. Never moved and to date I haven't had any problems.
Have you considered a Frost Protected Shallow Foundation?
I have been a suscriber to the mag forever and there is an excellent article on exactly what you want to do? but without about a half hour to remember where and when, I mentally bookmarked it so I could find it. If you would like I'll do it if your still looking for answers.
Drop a reply and I'll hunt it up for you.
Clay
Very interesting, always seems to turn out that way. That's what I love about this Magazine. They always seem to have covered my problem.
If you think of what it might be titled I will also look thru the archives.
Thanks in advance.
Off to look thru the online archives in more detail.
I think there was an excerpt in this past December (anual issue) - the one with a cake on the cover. They had an article on best const details or something.
It will tell you the exact issue from there.
Are you sure that wasn't a Rolling stones album cover from whay back, Hmm Bookmark bookmark where oh were is that issue. Hey I'll find it.What was it we were looking for ? Oh yea Rolling Stones Let it Bleed. I knew I could find it.
OK I'm still looking
Clay
Ever get that feeling, you know the world around you is trying to tell you something. So I had it in my mind that I could remember the cover and find it pronto. Opps gotta move that other cabinet out of the way to get to the first 85 issues, Hmmm I'm sure it's here someplace. Oh well 150 issues and didn't find it but what if it's from the other mag Hmm well let's keep looking ahhh yea at the very last stack of old folded Journel of light Construction(pre real magazine size). So the answer is JLC- vol 10-#6 March 1992 pg 23,24,25 One Step Stem wall foundations, by Jim Hart and Art Prindle. I think this is exactly what your looking for.
If you don't have acess to this article reply back and I'll see if I caan figure out how to make all the E stuff on my desk work, or perhaps if you have a fax I could E-fax it.
Back to the first line. So 2 days ago I get 2 letters from JLC peddeling cd rom of all articles. Oh well if the power goes out and I can find a match I'll still be able to find information.
Clay
Thanks so much for your effort. I did look myself thru all the Fine Homebuilding archives I could find with no luck. Your email explains that. Don't currently have access to JLC. If you don't mind faxing my number is 561-760-6418.
Thanks again.
Go to http://www.jlconline.com and click on Research.
Some of the articles are free, but all of them are available for $5 each.
Hey this playing on the computer is really fun almost better then working Ha Ha. Hey I gotta get to work but either tonight or in the morning I'll see if I can fax it to you. I've got a HP combo printer scann fax ect That should do it but It takes a little focus, still working on not bleeding on my projects. The pages might be a little cut off when I send it but I'll see what we can do, like I said, it;s so old the pages are the old big format and the scanner is only letter.
Clay
Have poured many monolithic stemwall/footing foundations here in the Pacific Northwest. Lot's of ways to go about it. The best way I know of is with steel straps (available at most concrete supply houses) as footing spreaders, then fasten regular form cleats to those with tek point screws to set the bottom of your forms in.
The one thing you said about a horizontal 2x to keep mud from spilling out of the top of the form is NOT a good idea (don't have the t-shirt, but I HAVE been there and done that). All you do is increase the chance of either a void, like someone mentioned, or worse - the hydraulic action of the concrete lifting footings, forms, your blood pressure...did I mention that I've tried this?
Like previously mentioned, pour it stiff, making the footing the first lift. And for God's sake, take it easy with that vibrator; I never pour without one, but they can turn a routine pour into a river of mud and blown forms in untrained hands. Been there, too.
Love concrete work, just don't particularly care for the stress right before the truck shows up.
If I hear you correctly then your stem wall would have to be about 4 feet high to be about 10 inches above grade. I figured you need about 4.6 yards of concrete for a 10 inch thick footing and a 4 foot high wall. That much concrete is way too much to mix by hand. Get a pump by all means. Don't bother forming the footing. The trench walls will be the forms for that. Just build the stem wall form. A 3 foot wide trench would be minimum width for room to work. Hold the forms up to the hieght of the footing and use lots of stakes and walers. Make sleeves for the stakes with tar paper to keep the concrete from locking them in so you can remove them the next day. A palm nailer is handy for nailing forms in tight places. Brace well and use lots of form wedge ties to prevent blowouts.
When pouring, use a vibrator to spooge out the concrete the proper footing width. Make the first pass to form the footing and then subsequent passes for the stem wall. Use a vibrator and watch the forms carefully to prevent blowouts. A stiff mix or minimum slump would be best. Screed the top and set the mudsill wet with the anchor bolts already in the mudsill to save a little time framing. You probably know you need vertical steel every 2 feet at least along with the horizontal steel for your footings and stem wall.