OT concrete forms

Need some practical advice regarding concrete forms for foundation walls. I'm in the design phase without a lot of good knowledge and haven't found a local mentor...yet. In general, want to pour a 6" thick wall, 48" tall wall, on top of a footing, most of it will be below grade to get below local frostline. 140 perimeter feet total. Top edge will be 8" higher than finished floor, the finished floor is referenced to the finish floor of an adjacent building. General idea is to set 4x8 sheets of plywood on edge to build the 48" height forms.

I found a lot of good info in the Dayton Superior catalog, these guys manufacture a wide variety of breakable cross ties and wedges specifically for such activity, geared towards wood forming. Cold headed and stamped products.

http://www.google.com/url?sa=t&rct=...6CsTQ5bMfMJel1E89kETaRw&bvm=bv.89381419,d.eXY

What I don't fully understand are....

1. In the catalog drawings, there is a 2x4 set flat side horizontal "attached" to the top face of the footing on both sides to act as a brace against blowout on the lower end. However no mention of how the 2x4 would be actually attached to the concrete. Two brainstorm options coming to mind are .22 cal concrete nails, or something like J-bolts pre-embedded on each side of the footing. Both seem to have issues, of either being hundreds of tiny wedges trying to split the green footing, or a lot of extra work to set and then leave behind a lot of J-bolts behind in the footing....and I don't recall ever seeing the latter either.

2. There are tables describing the spacing of vertical reinforcing 2x4s which are laid flat side against the outside of the form. However nothing really describing horizontal reinforcements. What I would like to do is use 2x6s on the outside of the form, laid flat side over top of the 2x4s. The idea being to remove and conserve/reuse the 2x6s as the framing lumber for the building. Silly idea or some merit.

3. understand "form release oil" is to be sprayed before placement. Anything I might have in the shop which I could use? Or if not what is next best? Is it a good idea to use latex paint on the top edge as a form of weather protection as this is built or unnecessary?

4. There is a local craigslist listing for 70+ pieces of 1-1/4" AC ply said to have been stored inside, sold at less per sheet than I could buy 3/4" new. So this has some attraction although I haven't seen it with my own eyes. I realize that must be heavy stuff definitely not a 1 man lift unless built like Lou Ferrigno, which I am not. But the structural aspect and price seems theoretically good.

5. To address "why not hire company with reusable steel forms give them drawings, and write a check". I have had generally bad luck with almost every building trade group I've ever hired and always regretted it later. Some combination of low quality work, make a giant mess without cleaning up, show up when they feel like it and more calls to understand the schedule seem to be met with greater spans between attendance, trying to do what I feel is price gouge me based on location. Bosses promise one thing and the working guys do opposite like they don't even know each other. I have to try to sort out between people in the phone book who has more attention to detail and who has less without much resources or leverage. Granted many of my experiences were from the "building boom" of some years back, so likely the lowest skilled people are doing something else these days. Don't want to turn it into a personal complaint session, but some of you must have been here before, I end up sick to my stomach at the aftermath almost every single time, so I've learned that I just want materials and even if its a lot of work I won't complain. I will spend significant time tweaking dimensions, square and level/grade because I'm also the guy doing the next phase of work and I don't want to have to stop and make new as-built drawings in the middle of the project in order to proceed . However, if some bad experiences have poisoned my brain to the point of being unrealistic regarding above then I need a sense check too

I estimate roughly $1200-1500 to buy the materials (not including concrete) to form the walls above, with the idea of reusing the horizontal stiffening 2x6s for framing lumber later (realize not every single one will survive but hopefully most). I could of course get a quote on the wall project using a company with reusable forms, but I am guessing its going to be significantly more than this compared as closely as possible. 2 guys x 2 days is probably going to eat $500 right there, just considering their basic wage but no profit for their company or consumables, etc.

As always, thanks for any help and advice, good alternatives, etc.

I was around while a parking garage was formed and poured as the first floor of one of our buildings. They formed with plywood and sprayed it with diesel fuel from a pump sprayer to keep it from sticking. Also, i am far from an expert at this but i think they mostly pevent blowout by tying boyh sides, in and out, to each other. I think there are some companies that make some hardware for this.

I just looked and dayton superior has some hardware for this

Form release can be kerosene or Diesel fuel. I suppose used drain oil would work. Might also paint the forms as a release. Used to be forms were made from the floor joist 2x lumber then it was stripped from the concrete and used as joists. You will need rebar inside the wall and hold downs every four feet. Make sure you use the square washers the round ones are not code anymore, too small. here they have to run a lot of steel from the bottom of the foundation to the roof to hold it all together in a quake. Also required in a hurricane or tornado area, which is the rest of the country.
If you are going six feet deep might as well go eight feet and get a useable basement for not much more money.
Bill D.

PS: Henry Ford made cast iron concrete forms to bolt together and make cast concrete houses.

Thomas Edison?s Beautiful Failure | Braving the Wilds

Matt,
Just a suggestion. Not sure I understand the requirement for a poured in place concrete wall. "Down heah" we use very little of that for holding up a slab, really only gets used if it is a deep footing or has to take a bunch of stress like an elevator pit. More often used is concrete block with vertical reinforcing in solid grouted cells. 8" block would give you about the same strength as your 6" poured in place.
Footing is poured with horizontal reinforcing plus vertical bars placed to line up with the cells. Block is then laid by setting it down over the vertical bars, for 48" you could grout when you have it topped out.
I've got details laying around the office I could share with you if you are interested.

Matt,
If your footing is poured and is reasonably flat then I would go with ICF's. They are really fast and easy and economical for a first time concrete wall build.
I could set and place all the forms for that wall including all the rebar in a day at the most but I have done a few. At 48" tall it works out well with standard blocks that are 16" tall.
If you can put lego together then you can use ICF's. 8" is usually standard for foundation walls IMHO.

My wife and I did our shop basement walls, 10' tall and we did it ourselves in about a week. The sales rep for our blocks came and helped us with the pour, part of his service.
For the record we used ARXX blocks and they are very good. Make sure you get the ties and the wall stiffener grid. The ties secure each block to the block below, tightening up the assembly, making it very sturdy, the stiffener does what it says and stiffens the wall lengthwise. A few braces inside and out to secure the top and you will be pouring concrete before you can believe it!
The insulated concrete will cure to a much higher strength than normal due to the slow cure, just don't backfill it the next day unless you are filling both sides, even then I would leave it for as much time as you can. No worries about pouring on cold days.

If you decide to go this route and have any questions along the way I am happy to answer any and all.

Michael


ps, can't believe people still use the old plywood system..... or fax machines!

You can rent aluminum forms. I rent mine for $7 a linear foot. Go find a local concrete supply shop and ask to see if they rent forms. Make sure you spray the inside of the forms with a release agent. Good luck.

If you have not poured your footing yet you can install clips that will hold the plywood form in place at the bottom. Many options to form it. I just rented 800 feet of 2 x 8 ft. form from Mason supply. cheaper than buying the plywood.

I used cheap 3/4" particle board. Saved the walers, etc for use in the building.

Stuart

Matt:

In response to your questions:

1) Many people use PAFs to anchor the bottom 2x4. You need to recover the 2x's - don't leave any wood in the trench.
2) There's no simple answer to this one. The pressure in a 4' deep form (at the bottom) is in the range of 750 PSF so you have to be careful. The snap ties do most of the work but the 2x walers are needed to limit deflection. For a definitive discussion the bible of form design is Mark Hurd's Form Work for Concrete.
3) Any oil will work - even used motor oil. No need to paint the edge - just oil it.
4) I'd just use 1/2" cdx. You'll find a way to reuse that. The 1-1/4" is overkill.

I'd like to suggest a couple of alternate ideas:

First, we've done a lot of foundations around AA by simply cutting a narrow foundation trench - say 12" wide x 4' deep. Then simply slip the reinforcing cage into the trench and fill with concrete. An 8" or 10" form board could be placed around the trench top to give you the proper height. This method obviously requires a fairly cohesive soil. You mentioned you have sand, but even with a little clay it usually will hold for the short time until the concrete is poured. This technique uses extra concrete, but saves a huge amount of time and form materials.

Alternatively, the steel forms you mention can be rented for a DIY project. Call FomTech in Wixom to see if they have what you need. (248) 344-8260.

Regards,

DB

NB: PAFs = powder actuated fasteners.

There are also foam modular forms that go in pretty slick.

I like ICF(integraspec), its a bit of $ but good stuff and pretty quick and insulates.

I've seen the concrete pump guys spray the hopper with hydraulic oil before starting to dump concrete into it, they say it cleans up a lot easier.
When I did my footings here last year with 2x10"s I used a concrete sealer I had, no smell to it, worked fine on wood(2-3 coats) and it was easy to clean them all after to reuse for framing the 2nd level. I wouldn't want to use something that will stink if its to be reused eh.

Probably easier to rent anyhow if going with forms.

Wow, I haven't done this work for almost forty years now, but let me weigh in anyway.

matt_isserstedt said:

1. In the catalog drawings, there is a 2x4 set flat side horizontal "attached" to the top face of the footing on both sides to act as a brace against blowout on the lower end. However no mention of how the 2x4 would be actually attached to the concrete. Two brainstorm options coming to mind are .22 cal concrete nails, or something like J-bolts pre-embedded on each side of the footing. Both seem to have issues, of either being hundreds of tiny wedges trying to split the green footing, or a lot of extra work to set and then leave behind a lot of J-bolts behind in the footing....and I don't recall ever seeing the latter either.

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J bolts sounds like way too much work. We just shot the plates down with a Ramset gun (Hilti these days, I guess) but the self drilling concrete screws should work, too. We only ever put one plate down, on one side, whichever side we were going to set up first. The plate isn't to keep the wall from blowing... a basic tenant of this sort of form work is it supports itself - pressure against the two sides is balanced and resisted by the form ties, so the only purpose of the plate is to hold the base of the wall in place.

2. There are tables describing the spacing of vertical reinforcing 2x4s which are laid flat side against the outside of the form. However nothing really describing horizontal reinforcements. What I would like to do is use 2x6s on the outside of the form, laid flat side over top of the 2x4s. The idea being to remove and conserve/reuse the 2x6s as the framing lumber for the building. Silly idea or some merit.

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For your skinny little 4' wall, all you need is 2x4's 16" O.C., with the tie holes 16"O.C. Lay out the pattern starting 8" from each edge of the sheet. Stack the sheets as many as you can drill through and drill multiples.

I understand the desire to use 2x6 and reuse them for studs, etc. Talk to the supplier you rent the clamps from; I'm sure you can get ties with custom length tails for whatever thickness plywood and framing you want to use.

3. understand "form release oil" is to be sprayed before placement. Anything I might have in the shop which I could use? Or if not what is next best? Is it a good idea to use latex paint on the top edge as a form of weather protection as this is built or unnecessary?

Click to expand...

Don't use oil if you are going to reuse the lumber. Oil stinks forever. Interesting fact is new plywood doesn't need oil; there are enough natural oils in the wood to keep it from bonding, especially if you strip it soon after the pour, like 2-3 days. You can likely even get a second use without oil. Worst possibility is the face plys try to stick to the concrete and you'll have to scrape them off with a shovel. This is a foundation wall, right, not architectural concrete.

Basic procedure. Shoot the plate to the footing one plywood thickness back from the inside wall line and nail the plywood enough so it stands up. Brace the first sheet, nail a scrap across the joint to the next sheet, start putting ties and walers when you get a couple sheets up. Working alone, definitely rent the clamps that use only one 2x4, I know them as "Jahn clamps", as they can be placed on the tie and the 2x4's added after the clamps are on the plywood. Oops, your desire to use 2x6's may rule this out and you'll have to use "hair pins" and double walers.

After one side is fully stood up and braced, you can tie your rebar to the dowels coming up out of the footing. Resist the urge to tie the rebar to the wall ties, as it makes it hard to close up the second side when the ties won't line up with the holes. Close the second side and brace to keep the wall plumb.

Don't cut the plywood to grade. If the footing is pretty good, the top edge should be close to level. We always had an instrument on the job (builder's level, like a transit but without the vertical swing). Now-a-days it would be a laser, but the old hose level would work, too. We just snapped a line on the inside of the plywood at grade, and set 8 penny nails every couple of feet in case the line got washed off. If the top if the wall was to be finished, these were pulled while waiting for it to firm up enough to edge and trowel.

Good luck. Sounds like more work than I want to do.

Dennis

Check out Simpson Strong-Tie Simpson Strong-Tie®

Look for the "WT" wedge form ties. I have used them up to 72" high with a wall thickness of 12". They allow you to use your floor joist lumber for form boards.

As far as anchoring the 2x4 sleeper to the footings, we would use a 1/4" roto-hammer to drill through the 2x4 into the footing then drive 2 16d duplex nails into the hole together. They never ever came loose or blew out. They will come out easily with a big pry bar.

SND said:

I like ICF(integraspec), its a bit of $ but good stuff and pretty quick and insulates.

I've seen the concrete pump guys spray the hopper with hydraulic oil before starting to dump concrete into it, they say it cleans up a lot easier.
When I did my footings here last year with 2x10"s I used a concrete sealer I had, no smell to it, worked fine on wood(2-3 coats) and it was easy to clean them all after to reuse for framing the 2nd level. I wouldn't want to use something that will stink if its to be reused eh.

Probably easier to rent anyhow if going with forms.

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This is another option....Superior Walls - Simply Superior there are a lot of other insulated foam panel systems. I wish i forced ny builder to use these guys when i built my house, life would be much better .

dee
;-D

In this neighborhood nearly all form work for residential construction is done by contractors that do nothing else. Check out any local new subdivision under construction for those guys. Save your back for the carpentry.

Most walls that I see are 9". It depends on what exterior detail that you are using with brick needing (" or more.

3¢

Have you looked at AAC? Autoclaved airated concrete. It is not available here on the west coast last I checked anyway. Think of it as large bricks, set with thinset that is insulating and load bearing (within reason).
Building with AAC - Concrete Construction Page 1 of 2
Better link
Autoclaved Aerated Concrete

Rob

matt_isserstedt said:

Need some practical advice regarding concrete forms for foundation walls. I'm in the design phase without a lot of good knowledge and haven't found a local mentor...yet. .......................

...........................

5. To address "why not hire company with reusable steel forms give them drawings, and write a check". I have had generally bad luck with almost every building trade group I've ever hired and always regretted it later. .......................

..............................

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Here's your mentor. Buy the JLC magazine archive. Best $60 you will spend.

JLC Archive USB - JLC Online


Been there and hear you on the contractors. BUT, there are good ones out there, you just have to find them. If you were getting things done from 2003 - 2007 you were getting the guys who couldn't get regular work from the general contractors, that's not the case today, at least not around here. Find people who have been living in the area for decades and see who they recommend. True, it's not easy and if you haven't learned yet, don't bother asking for three references. No matter how lousy they are they will always be able to give the number for their uncle, their neighbor and a guy they owe money to vouch for their work. You need to visit current job sites and visit very recent jobs to get a decent assessment.

Just a thought on ICFs, yes they would work great for forming up your foundation however, first, they are fairly expensive. Second, the finished wall will give you 2" foam, 8" (more or less) of concrete and then 2" of foam. The foam is not load bearing so if you are planning to frame up a stud wall on top of it, a 2" x 4" wall will have 2" sitting on foam and 1 5/8" sitting on concrete which the inspector will fail. I was told you need to have no more than 1/3 sitting on the foam so that means a 2" x 8" wall.

Steve

Just a thought on ICFs, yes they would work great for forming up your foundation however, first, they are fairly expensive. Second, the finished wall will give you 2" foam, 8" (more or less) of concrete and then 2" of foam. The foam is not load bearing so if you are planning to frame up a stud wall on top of it, a 2" x 4" wall will have 2" sitting on foam and 1 5/8" sitting on concrete which the inspector will fail. I was told you need to have no more than 1/3 sitting on the foam so that means a 2" x 8" wall.

Steve[/QUOTE]


A rebuttal for that last paragraph.
ICFs are not expensive when you compare the labor savings and other benefits. Doing it yourself with perfect results is going to save you money and stress.
2x6 walls are just fine on top of an ICFS wall, there are several options, including just using a flashing to cover the foam on the outside wall, as a bonus buildings look good when the foundation steps out. I used some 16 gauge sheet metal to cover the foundation on our house, it looks great and is rusting to a nice patina. I used a copper flashing to transition to the wood siding.

I recently poured about 18' of wall 4' tall. We suspended the foam blocks and poured the footing and wall in one day with hand mixed concrete. Once poured there is very little stripping to do with ICFs.
If you can't tell already I am a huge fan of ICFs, no one could pay me to form concrete the old way.

Good luck.

Michael

Why not just dig the footers as deep as needed(use the ground as your form) and use block for a few courses to get above the grade?

SteveF said:

Second, the finished wall will give you 2" foam, 8" (more or less) of concrete and then 2" of foam. The foam is not load bearing so if you are planning to frame up a stud wall on top of it, a 2" x 4" wall will have 2" sitting on foam and 1 5/8" sitting on concrete which the inspector will fail. I was told you need to have no more than 1/3 sitting on the foam so that means a 2" x 8" wall.

Steve

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Steve you use a tapered top form for the last course. The top of the tapered form ends up almost all concrete. Not sure on the final dimension. Legal for a 2x4 wall.


Tim

I've only done a few foundations and none like the OP's so I don't have any useful advice there. But just because it hasn't been said- it's worth it to have someone look things over prior to the pour; a blowout is a disaster. If OP is confidant in the structural integrity of the forms and wants to skip that, fine, but just be damn sure things are solid as hell and level and square and plumb. Once the mud starts flowing, there WILL be a monolith of concrete there. Just what shape it'll be is in question.

As to the pour, hire some help, ideally experienced help. Once the mud starts pouring, etc. Do not pour on a hot day. I did pour my most recent on a hot day and I did not have an experienced crew and it damn near got away from us- we just couldn't get around it to screed/finish it fast enough. That's terror right there.