PDA

View Full Version : Footings and Stemwalls



Tim Uhler
01-31-2008, 02:22 PM
Now that the market is slower, we are going to be doing more in house than we've done in the past 5 or so years. Back when I was just a laborer and clean up guy, the framers did the foundations, flatwork (slabs, patios, walkways and driveways) framing and siding and often the trim.

In the early 90's when the market got slow, we went from a few crews to two guys and me after school. So I learned how to do foundations.

The last time I really did any foundation work was 03 and we did a total of about 10 in a couple of months. Only one since then. Always with my mentor Dave.

We have to set up walls tomorrow and I'm really looking forward to it. But I wanted to benefit from the experience on the forums.

The way we typically set up footings is with 1x6 boards, lifted and nailed to stakes level so we have a minimum 8" of depth. What we used to do is setup, get inspection, pour (place), clean up a bit, then snap lines and set spreader cleans with a 1 1/2" nail holding the cleat to the concrete.

Next day, tie bar, set forms, get inspection, pour in the late afternoon. Next day strip the outside, excavator grades the lot. There were times when we started framing the next day.

Smaller houses.

I'm comfortable forming walls. The footing we set up last June to extend a permit wasn't poured by us. It was poured by the foundation sub who did the foundation down the street for a custom we are working on.

We use the 1" x 2'x8' MDO forms. My question is, is it a waste of time to shoot a nail into some of the clips to keep the forms on the snapped line?

Also, I'd love to hear from everyone how they form up footings and stemwalls.

Mark Parlee
01-31-2008, 10:52 PM
Tim

I hope you take plenty of pictures

David Meiland
02-01-2008, 12:53 AM
Tim, we form the footing and stemwall all together and pour it once. I have some good photos on my other machine, and I'll post a few.

Steve Unkie
02-01-2008, 02:55 AM
I would vote for a mono pour. I would also be interested in seeing and hearing about your favorite methods.

Steve.

Tim Uhler
02-01-2008, 09:36 AM
We've only done mono pours when its a smaller job. But I'd like to see the pictures. I'll try and get some today too.

wallmaxx
02-01-2008, 10:29 AM
Tim

I am used to the south TX way of slab on grade. Since moving to WA I have been working with Gen Nail Bender, and he has been trying out the Certainteed Form-a-drain, when setting up his footings. He also is working with ICF...its a very cool form / insulation concept.

Slabs, monolithic pour. Basements...1. Footings, 2. Walls, 3. Floor

Mike

David Meiland
02-01-2008, 11:11 AM
Tim, here's the general idea of what we do. Form footing, toss in rebar, add 1x4 cleats and stake everything in place. Then, snap layout on the 1x4s, attach form panel spreaders (from Award Metals I think), stack outside panels, tie rebar, stack inside panels.

gregoryj
02-01-2008, 11:30 AM
David, are the 1x4 cleats trapped in the wall and abandoned? If not, when and how do you remove them?

David Meiland
02-01-2008, 03:26 PM
Those are in there for good. I put an addition on a 20-year-old house last year and we dug up the foundation on a couple of sides. There was mostly well-drained gravel against the footing. The 1x4 was in perfect shape. In you backfill with clay soil I wouldn't be as optimistic, but we never do.

Dick Seibert
02-01-2008, 03:57 PM
We've always poured the footings with the walls, even 8' high walls. At first we used 1x8s for the forms with 2x4 walers, then reused the 1x8 as subfloor, when plywood arrived on the scene for subfloors we started using 2xs for our forms reusing them as floor joists. Then the inspectors started giving us a bad time about reusing the lumber so I bought plywood reusable forms from a retired contractor, eventually building my own and oiling them between uses. About 1974 our codes and engineers went to all pier foundations and all we formed were grade beams on top of the piers, since then we have been pouring the piers first with the steel cages sticking up, and then forming 18" plywood forms with walers on top of them later.

In the old days we tied them together with #9 wire using wire twisters with knockout wood spreaders, then snapties (http://www.sweethaven02.com/BldgConst/Bldg02/fig0611.jpg) came on the scene and we no-longer twisted wires.

Ted S.
02-01-2008, 05:23 PM
We use the Symons forms and ICF. On both we use 2x10 lumber to form the footing, along with 1x3 spreaders and perforated strapping to hold the bottom in, although we now are just backfilling the form to hold it in. After the square and level, we pour and strip the footing, pretty much the long way of doing things. They now have these spreaders that hold the footing form in, here is a shot of one attached along with some prefab keyways. One thing, we don't always level the top of footing, we snap a line on the elevation and trowel to that, it way easier than trying to lower the form if it is high.

We nail the outside form on the line, erected the outside shell, insert bucks and rebar, erect the inside shell, slip the ties and the hammer the dogs into the ties. Then clamp 2x4's to the top, align the forms with turnbuckles and stakes. We also insert brackets and lay some plank to walk on during the pour.

I would say you have to nail to the footer, can't see how you couldn't although there are probably a number of guys who don't, including my father in law, my mentor who taught me. I think I'd be afraid of form float, although that must be due to my ICF background vs. him doing it for 30 years. If you set the footing back in June, you might have a tough time nailing it. But I wouldn't skip the detail, when the forms move during the placement you always crap yourself pissed that you skipped the odd brace because you though you had balls.

BigLou80
02-01-2008, 06:19 PM
.

But I wouldn't skip the detail, when the forms move during the placement you always crap yourself pissed that you skipped the odd brace because you though you had balls.

learned that lesson the hard way.

marson
02-01-2008, 07:27 PM
I can't comment on stemwalls since we rarely see them--all basements here, and mostly ICF's. I have used 2x10's for footing forms. We use steel or wood stakes and 2x4 spreaders. We laser the hole and find the high spot and that's our minimum thickness. A detail we are required to use is a 3" PVC weeper every 6 feet or so to allow connection between the interior and exterior drain tile. We are in heavy clay, so once the excavator has the hole, we jump in and form and pour footings ASAP. If you get rain before the footings are in, you have a real mess. So I don't think anyone around here pours footings and walls in one fell swoop.

The next chance I get I am going to use form-a-drain. I watched a sub we had use them. They laid them out, placed their reinforcement, and made spreaders out of pieces of the form-a-drain cut so it sort of had ears that wrapped over the top of the footing forms. this also provided the weepers. Right before the pour, he went around and set them to grade with 1x3 stakes and drywall screws. No need to strip forms, and it provides a much more durable drain tile.

The last job was scribed to bedrock. We hammer drilled in chunks of rebar and set 2x8's on them using fence staples. Then we scribed plywod to the rock. That was a chore.

What do you guys do about vertical reinforcement for the walls--pre place, wet set, or drill in later? We drill ours in the next day. Our inspectors are fine with it since it really is there for shear, this not being a seismic zone.

We always have to wait for backfill. In cold weather, it is a minumum of 7 days curing before backfill. Years ago, we always capped the floor before backfill, and then went inside and braced, but these days we backfill before both the basement floor and the floor deck. This allows the excavator access to prep the slab. Makes pouring the floor a bit easier.

Tim Uhler
02-01-2008, 08:09 PM
Got some pictures. We could have finished today, but I shorted us a lot on snap ties and shoes.

Actually went really well. My back is a little tired, but Matt and I had a lot of fun.

http://picasaweb.google.com/TimothyUhler/MountainView

David Meiland
02-01-2008, 09:14 PM
Tim, did you pump or chute those footings? What about the walls?

Dick Seibert
02-01-2008, 09:23 PM
Tim:

A problem I see with pouring twice is the cold joint, there is no way you are going to waterproof it and it's going to allow water come into the crawl space, I was going to say when people water their yards, then I remembered that in Washington they don't water their yards, it rains all the time, but that means water is going to be running in there all the time.

In the late 50s and early 60s some cheapskate builders tried CMU foundations where the block was laid on footings poured in open trenches, they failed miserably and from what I saw most of the complaints originated from water running through the cold joint on top of the footing.

When we went from "T footings" to "pier and grade beam" foundations the cold joint was such a concern for me that I started trenching before drilling, then drilled in my trenches, that upset the soils engineers because they specified 2" Styrofoam (or cardboard) under the grade beams so the water could flow under, I showed them that it was there, down in the trench, and they checked that we knocked it out, but they weren't very happy. Homeowners hate water under their houses, no matter how much engineering you show them.

Tim Uhler
02-01-2008, 09:30 PM
Tim, did you pump or chute those footings? What about the walls?

We didn't pour them. But we'd have used a line pump and will for the walls. In the old days we tailgated everything. Now we use a pump more often, but it's been a few years since I did a foundation. We used a line pump on that one.

Tim Uhler
02-01-2008, 09:36 PM
Tim:

A problem I see with pouring twice is the cold joint, there is no way you are going to waterproof it and it's going to allow water come into the crawl space, I was going to say when people water their yards, then I remembered that in Washington they don't water their yards, it rains all the time, but that means water is going to be running in there all the time.

In the late 50s and early 60s some cheapskate builders tried CMU foundations where the block was laid on footings poured in open trenches, they failed miserably and from what I saw most of the complaints originated from water running through the cold joint on top of the footing.

When we went from "T footings" to "pier and grade beam" foundations the cold joint was such a concern for me that I started trenching before drilling, then drilled in my trenches, that upset the soils engineers because they specified 2" Styrofoam (or cardboard) under the grade beams so the water could flow under, I showed them that it was there, down in the trench, and they checked that we knocked it out, but they weren't very happy. Homeowners hate water under their houses, no matter how much engineering you show them.

Dick

I can't tell you how many times I've been in crawlspaces while its raining cats and dogs outside. Water will come in where the plumbing comes in from outside, so we take care of that. Otherwise, its not an issue.

Most by far of the foundations in this area, are poured twice. What has changed under the 2006 IRC update, is that we are supposed to waterproof that joint. It didn't used to be that way.

Another change is that we have to tie a 20' stick of rebar and bend it so it sticks out of the foundation. That is then used as the ground for the electrical panel. That way it uses the entire foundation. Our electrician told me that last week, so we'll do that and leave it sticking out between studs in the garage, or whereever he tells us to put it.

Tim

PS, I'll try and get pictures of that.

Dick Seibert
02-01-2008, 10:11 PM
Tim:

If code is requiring you to waterproof it, how are you going to waterproof the cold joint?

It sound like you are required to do a U-fer ground, that's been in the code for over 30 years. I can't believe he's going to let you stick a rebar out, you are suppose to have the electrician run a 2' copper wire, attached to a length of rebar with special bonding clips, and then up at the service location (this is in addition to bonding to the gas pipes and one or two driven copper ground rods depending upon the soils report. Here is a checklist from one of our cities, note that they make you install the 20' 2" from the bottom of the footing, most AHJs allow you to bond it anywhere in the footing or stem wall, and actually prefer running it down a pier hole if your piers are 20' or more in depth.

Foundation
1. Soils report
2. Inspection report of post tension cables prior to concrete pour
3. Correct footing depth
4. Proper size and number of reinforcing bars in top and bottom of footing
5. Check for pier footings and mats
6. Reinforcing bars to have 3” clearance where permanently exposed to earth
7. Check for Hold Downs, Post Anchors and Column Bases
8. Ufer ground rod located (20ft in length located 2”" from bottom of footing)
9. Visqueen and sand bed for slab
10. Proper reinforcement for slab
11. Plumbing pipes wrapped
12. Electric and telephone sweeps installed

Here is how you have to bond it (http://www.greaves-usa.com/pdf/jones_bond_nec2002.pdf). I wouldn't play around with this Tim if the inspector is too dumb to know about proper electrical grounding, if someone gets electrocuted in a house and you didn't install the code complaint grounding your dad issure to get sued.

Ed Michnick
02-01-2008, 10:49 PM
Tim:

If code is requiring you to waterproof it, how are you going to waterproof the cold joint?

All of the residential foundations around here are poured in two steps with the footing firsts and than the walls. After the forms are stripped the drain tile is layed with gravel over the drain tile and than the foundation is waterproofed, followed by a backfill inspection.


It sound like you are required to do a U-fer ground, that's been in the code for over 30 years. I can't believe he's going to let you stick a rebar out, you are suppose to have the electrician run a 2' copper wire, attached to a length of rebar with special bonding clips, and then up at the service location (this is in addition to bonding to the gas pipes and one or two driven copper ground rods depending upon the soils report. Here is a checklist from one of our cities, note that they make you install the 20' 2" from the bottom of the footing, most AHJs allow you to bond it anywhere in the footing or stem wall, and actually prefer running it down a pier hole if your piers are 20' or more in depth.


Here is how you have to bond it (http://www.greaves-usa.com/pdf/jones_bond_nec2002.pdf). I wouldn't play around with this Tim if the inspector is too dumb to know about proper electrical grounding, if someone gets electrocuted in a house and you didn't install the code complaint grounding your dad issure to get sued.

I don't think Tim is doing anything wrong here Dick. I have never ever saw a Ufer grounding system used on any residential house around here. Anybody out there ever have to install one? Maybe it a regional thing, but around here a grounding rod into the soil seems to pass code fine.

marson
02-01-2008, 10:54 PM
It sound like you are required to do a U-fer ground, that's been in the code for over 30 years. I can't believe he's going to let you stick a rebar out, you are suppose to have the electrician run a 2' copper wire, attached to a length of rebar with special bonding clips, and then up at the service location (this is in addition to bonding to the gas pipes and one or two driven copper ground rods depending upon the soils report.

In these parts, we are just sticking a piece of rebar out of the pour as well. I always thought it was funny that the electricians never come and see to it nor does the electrical inspector inspect it. For all they know, it could be a 12" chunk of bar stuck out of the slab. The power company does test your ground when you hook up, I know. Perhaps that's all they need to know. If they test it and it is a ground, I'm not sure how you would be liable.

David Meiland
02-01-2008, 10:56 PM
We can use either 2 ground rods 6' apart, or a Ufer ground. The Ufer is so easy it would be silly not to do it, and you can avoid having to run copper to the outside of your building. Tim, we don't "daylight" a piece of rebar for the ground connection, we run the copper ground wire right into the footing pour and then bring it up to the panel. If you know where the panel is going you can embed the ground close by. I have heard of daylighting rebar for a ground connection but I believe you would then need to allow access to the clamp that makes the connection. That might be hard to do nicely if it's in a wall that gets filled with insulation.

Maybe someone's brave enough to go over into the Electric Shop and see how they do it.

Ed Michnick
02-01-2008, 11:03 PM
Maybe someone's brave enough to go over into the Electric Shop and see how they do it.

I just posted a question over their.

This is very interesting. Depending where you are in the country how different the codes are.

David Meiland
02-01-2008, 11:09 PM
Overall I'm a little disappointed in some of the electrical code enforcement here. A while back there was discussion of the requirement for a grounding mat under a hot tub installed on grade. Makes sense to me. When I asked my electrician about it he said they never do that, the inspector doesn't require it. There have been a few other things I've come across that are similar.

Right now I'm building in a spot where we would not be able to use either rods or ground plates easily at all. There is less than 30" of soil over the ledge, much less in most places. Without a Ufer we'd be struggling, probably running ground wire way up into the woods above the house.

Dick Seibert
02-02-2008, 12:28 AM
I just Googled the date it came into the NEC and the answer was 1968, they went on to say that it wasn't strictly enforced until 1978, I could have sworn that it was 1977 when I first got hit with it, I had three buildings under construction at the time, and inspectors in both Contra Costa County and Oakland made me put them in. The reason it hit me so at the time is that it meant bringing the electrical contractor in for a special trip between near the end of the forming and before the pour, sometimes a hard thing to do to get them to make a special trip on a day's notice, once I learned I started forming the area beneath where the service was going to go first to give a little latitude, before that they use to just give me a big angle to bury in the footing for underground services. Link (http://forums.mikeholt.com/showthread.php?t=91841)

If any of you have been on the NEC between 1968 and now and have not been installing Ufer grounds, your inspectors don't know what they are doing because hasn't everybody been on the NEC? Lets face it it took them 10 years to figure it out here, so in the boondocks they may still not have figured it out! Hey Tim, with Microsoft up there in Washington you'd think they knew what they are doing, on the other hand I don't see any hold downs in your foundation, and from your earthquake zone they are suppose to be all over the place, especially f that's going to be a two story home, and it looks like it is from the surrounding homes. Get those guys up to speed, but being public servants most of them are just working for paychecks. I still want to know hoe you are going to waterproof that cold joint since you say code requires it, apparently they do know about that.

Lavrans
02-02-2008, 12:53 AM
There are several types of waterstops that you cast into the footing that bridge the cold joint. These are the only way to stop water intrusion in high water travel areas, and should be used in addition to waterproofing if in prone areas (downslope in high rainfall areas, groundwater, etc.). Not many people use them because most of the time water moving through the footing/stemwall cold joint will disperse under the slab first, & will require quite a bit of water to make it to the slab. Most people aren't going to be as litigious w/o a puddle, and chalk up high humidity to the rain, but don't infer that it means a big puddle under their slab.

Dick Seibert
02-02-2008, 01:03 AM
Lavrans:

That's fine for slabs, but people like Tim, myself, and most here don't build homes on slabs, so water sits under houses. The question is, what is going to do about it now? It sure seems like to would be a lot cheaper and better to pour the walls and footings together, in fact I see no advantage to pouring them separately. Can you think of any? I say form everything up, get a boom truck out and pour it all at once.

Lavrans
02-02-2008, 01:46 AM
Lavrans:

That's fine for slabs, but people like Tim, myself, and most here don't build homes on slabs, so water sits under houses. The question is, what is going to do about it now? It sure seems like to would be a lot cheaper and better to pour the walls and footings together, in fact I see no advantage to pouring them separately. Can you think of any? I say form everything up, get a boom truck out and pour it all at once.

Well, I pour them monolithically when I can. But that isn't always possible: sometimes they have to be done in multiple pours. Sometimes it's just more economical to pour twice. Most of the time when that's the case, though, you're building on a steep site and should have very good drainage, so whatever makes it through a cold joint will have a direction to drain. Still, that's when you use a waterstop system to help direct the water & prevent it from getting in just because of a cold joint.

I have a friend who specialized in foundations up and down the coast and he would wet-place waterstops in complicated foundations where a stress riser existed he felt could crack. Those systems won't definitely stop water in perpetuity, but they are another line of defense. You also have to ensure there is properly prepared bed below the house that allows for drainage. You need to have a good footing, the waterproofing has to run down to below the footing, and have a good footing drain in place so water has a path of lesser resistance. That is true whether you're pouring in lifts or monolithically. Foundations crack, concrete is porous, water wants to go where it's easiest to go.

I think it's more important to have a complete design than to focus on any one part. Do you focus on the cold joint to the exclusion of thinking about cracks? How about the other penetrations into the interior envelope?

TSJHD1
02-02-2008, 01:54 AM
Lavrans:

That's fine for slabs, but people like Tim, myself, and most here don't build homes on slabs, so water sits under houses. The question is, what is going to do about it now? It sure seems like to would be a lot cheaper and better to pour the walls and footings together, in fact I see no advantage to pouring them separately. Can you think of any? I say form everything up, get a boom truck out and pour it all at once.

How would you support the wall forms?
How would you ensure the footing is completely full?

Tom

marson
02-02-2008, 04:15 AM
Regarding the cold joint which is going to leak, if you do a monolithic pour and have to leave a 1x4 trapped in the pour to support the wall form, isn't that eventually going to be a point of water entry?

Ted S.
02-02-2008, 08:29 AM
Every foundation around here gets the footing formed/poured/stripped and then the walls formed/poured/striped.

How do you form/pour a 8' wall ontop of a empty footing form? That sounds crazy.

fpopjr
02-02-2008, 12:07 PM
reguarding water seeping thru the foundation wall/footing joint- i always call for the underslab traprock to cover the footings a minimum of 2", then poly, styro & slab. if 12" or more of stone fill can't handle any water infiltration, maybe the house should be somewhere else. frank

TSJHD1
02-02-2008, 01:02 PM
How do you form/pour a 8' wall ontop of a empty footing form? That sounds crazy.

That's what I was saying.

DICK??

Tom

worthy
02-02-2008, 01:21 PM
Same question here.

A monolithic pour sure would have helped in my last build, when a large portion of the 10 ft. excavation walls collapsed onto the footings in heavy January rains--mostly thanks to the neighbour "testing" their strength by driving his van next to it. Nothing like the client calling you on a Sunday morning with the news that the neighbour's vehicle was in the excavation and I probably should be taking a look at it!

several types of waterstops that you cast into the footing that bridge the cold joint

What might they be?

Since I read Lstiburek calling for dampproofing the top of the footing before pouring, I do it. (Even though the subs all wonder what the heck I'm doing. "Never heard of that, guy.")

The form-a-drain sounds like a great idea. Eliminates all that wasted expensive lumber and the labour to take it up and out and to the dump. But I wonder if the inspectors will insist on the weeping tile drains as well. Years ago when I wanted to use crystalline waterproofing instead of cutback asphalt dampproofing, I was required to obtain an engineer's letter and provide documentation.

Lavrans
02-02-2008, 01:31 PM
waterstops:
www.cetco.com/bmg/Products/Waterstop/Waterstop-RX.htm
www.cetco.com/bmg/Products/Waterstop/Akwaswell.htm
http://www.henry.com/Concrete_Sealants__Waterstops.178.0.html

From Wikipedia, the free encyclopedia
Jump to: navigation, search

For a type of a railway stop, see water stop

A waterstop is an element of a concrete structure, intended to prevent the passages of fluids (such as water) when embedded in and running continuously through concrete joints. Waterstops are frequently manufactured from extruded plastics such as flexible PVC or thermoplastic vulcanizate rubber (TPV); formed metal such as stainless steel, copper, or carbon steel; or extruded thermosets such as natural rubber, Styrene-butadiene rubber, or neoprene rubber.

Hydrophobic Polymer waterstops such as PVC, TPV, or rubber are supplied to the construction site in coils (usually 50 lineal feet long), and are generally anywhere from 4 inches to 12 inches wide in a variety of profiles that are designed to simultaneously provide an interlock with the concrete they are installed in and provide for a limited amount of movement within the joint. PVC and TPV waterstops are made continuous for the length of the concrete joint by heat welding, using simple thermoplastic welding equipment [1]. Thermoset rubbers and metallic waterstops are more difficult to fabricate to continuous lengths and are specified far less frequently by architects and engineers.

TPV waterstops are generally installed in joints of secondary containment structures to prevent the passage of hazardous fluids other than water such as fuel oils, acids, or process chemicals.

[2]

worthy
02-02-2008, 01:57 PM
Thanks! The Aquadrain system looks quite interesting too. My biggest problem implementing any changes is that, aside from part-time general helpers, I work only with subs. And if they haven't heard of it, they won't do it.

Lavrans
02-02-2008, 02:05 PM
Are you as amazed as I am about how little many subs know about their own specialty? I am still looking for tile guys who've used Schluter, Noble, or one of the other sheet membranes, but the only thing anyone in Portland has used is Redguard "a couple times." Foundation guys are similar- in my experience it's hard to find one who knows anything expect form, rebar, concrete. Get into waterproofing, additional technologies, additives, residential guys just don't know, or don't want to admit to it...

Dick Seibert
02-02-2008, 03:58 PM
As I said above, since we went to all pier and gradebeam foundations around 1975 we pour the gradebeams on top of the piers creating a cold joint, we have to because they now inspect the piers separately from the gradebeams. When we did conventional T foundations we always poured the footings with the walls to make it in one pour and avoid the cold joint. I grabbed a picture from the Internet to attempt to show you how it's done, when I was an apprentice we used wood stakes, and to be honest sometimes they broke off trying to pull them out, the "invention" of steel stakes as a big advantage to us, I have stake pullers too, and they come out real slick even after a day or two if the engineer makes us wait to strip.

Forms (http://www.dickseibert.com/form1.jpg)

I built two Cyclotrons at Cal, both monolithic pours supervised continually by several engineers, one bigger than this picture, and the other smaller.
Cyclotron (http://www.castlegar.ca/eng/Images/Oct%2014.JPG)

BigLou80
02-02-2008, 06:05 PM
Ted S,
it can be done. I have done it for short sections of walls to repair blow outs and cracked sections of block and rubble stone walls. Its a big pain in the ass and it not worth it on a whole foundation job. I only did it to avoid a short load charge.

Lou

worthy
02-02-2008, 06:24 PM
Are you as amazed as I am about how little many subs know about their own specialty?

Sometimes they know, but pretend they don't. Asking a former to vibrate (http://www.cement.org/tech/cct_con_design_bugholes.asp) the pour, they look at you like you're a nut job. Last place, it was in the contract. Yet the former showed up with the pumper and three ready-mix trucks. No vibrator. I was the one off to the rental place for a vibrator and the generator to run it. Sheesh!!!

A masonry contractor I know tells me the foundations on subdivisions he works on (fixing and adding blocks) usually look like they're not vibrated. Hey, a buck saved is a buck saved!

Kgphoto
02-02-2008, 06:52 PM
Dick,

In our diagram, are those whalers or snap ties? I may not be reading the diagram correctly.

In LA, you have to vibrate anything over 12 inches deep. When doing tall pours, they are done in layers called lifts. Pour a little, vibrate, move down the line, pour a little vibrate, work your way around pour another foot or so, consolidate, vibrate, move on down the line repeat.

By doing it this way, the first layer stiffens up a bit so the next layer won't push it out. Consolidating and vibrating avoid cold joints and honey combs. Some patching may be required.

Stairs are poured the same way. Everything has pre-tied re-bar in place before the pour. Even though it is called a pour, you place it usually with a pump.

O'BrienConstruction
02-02-2008, 07:54 PM
Lavrans,
I attribute that to tract building. Where price is beaten down so far that the sub can only afford to do the bear minimum that code allows. This goes on for a while and becomes the accepted practice in that area.

GaryJR
02-02-2008, 09:20 PM
"I attribute that to tract building. Where price is beaten down so far that the sub can only afford to do the bear minimum that code allows. This goes on for a while and becomes the accepted practice in that area."

That is so true. It gets to where the work done, even at the minimum standards is barely worth doing at the price the builder is will to pay out to the sub.

Lavrans
02-02-2008, 10:16 PM
That makes sense. Tract hell. But still doesn't excuse the lack of interest.

I guess if you're only doing it for a buck, and only see it at the bottom of the spectrum, then there's no reward for knowledge. But I'm not trying to find the cheapest guys- they cost too much in the end, and the work isn't very good. I'm trying to search out the guy who knows his trade & at least tries to stay on top of it: I hate knowing more about a trade I don't do than the guy I'm hiring to do it! I'm willing to pay more, and willing to spend the time explaining the benefits to the owner, and most of the time have already pre-sold the upgrades, only to find that I can't find anyone with any experience to do the work.

Eh. That's one reason I haven't been doing much GC work lately. No good help, to hire or sub. Now I just act as the overly qualified finish guy/woodworker. I can't look at a job from just one trade's perspective, so now I wind up supplying free consultation services... Oh well. It'll pay off some day, right?

Dick Seibert
02-02-2008, 11:05 PM
Kirk:

That's my editing of an Internet drawing, the yellow is walers (I thought it was spelled "whalers" too until this morning, so don't feel bad) and studs, the black is my added steel stakes, and of course the red notes are my comments.

At to snap ties, I've seen them evolve like this (http://dickseibert.com/ties3.jpg).

As to tract work, I've laid off good carpenters for lack of work and they've gone to work in the tracts, when I got busy again and brought them back they were all ruined for life, after a stint in the tracts they all seem to think that a carpenter's main tool is a caulking gun!

Ted S.
02-03-2008, 09:57 AM
I'd be interested in seeing the details for the monolithic pour on a 8' wall, I've wanted to try it with an ICF wall but never figured out the details. Never really had the opportunity, next year I might thought. How do you support the wall? on top of the 1x3s?

Lavrans
02-03-2008, 01:29 PM
I think people are attributing a lot more weight to the concrete than there really is on the wall. When pouring a monolithic pour, so long as you are doing it in lifts, the concrete at the bottom is setting up and is able to carry quite a bit of weight. You have to go at the right pace.

The formwork can be quite heavy, but with enough crossmembers in the footing it can hold the forms fairly well. I built an 8' tall retaining wall with 36" wide footing, offset, and poured monolithic (it was only 20' long). I don't have a picture, but I used plywood cut into "L" that spanned the open area & held the wall suspended. I built the wall sections with 1" pipe spreaders that were left in for the pour & became the weep holes. The wall was held 1" above the top of the footing forms (just cut slope on the bottom of the plywood brackets). Quick mono-pour for that. A house would be much easier because the footings are narrower & the wall is centered in the footing.

I have poured smaller walls with the steel tabbed spreaders that sit on top of the footing form. They are meant to be left in place, but it seems they would make something to support more weight. But anything left in a monolithic pour becomes an opening eventually.

Dick Seibert
02-03-2008, 02:01 PM
Ted:

I tried to make a detail of how we do it with this sketch (http://www.dickseibert.com/form1.jpg) I posted above, if you want more detail I'll try to make a more detailed drawing, I should really learn Sketchup, I do these in Photoshop. Before I undertake doing this I need to know if you are using pier foundations like we do now, or spread footings like we did prior to the early 70s?

Lavrans is right, we pour the footings first vibrating them well, then we go back around as they set and start pouring the walls around the building about 12" per lift, with an apprentice following the hose with a long vibrator. We go around the building several times until we reach the top. The trick here is to vibrate enough to prevent honeycombs, yet not too much so the concrete doesn't push out the footing, or heaven forbid, push out the forms. I'm a nut on honeycombs, I make it well known that if there are any honeycombs evident when we strip, that apprentice running the vibrator is fired! Nothing speaks higher for a contractors reputation than the quality appearance of his concrete. The spacing of your snap ties is very important too, even when you remove the cones and epoxy the plugs in they can still be seen.

David Meiland
02-03-2008, 03:59 PM
Never done 8' walls but I've done 4-5' walls monopoured with the footings and it's no problem. The first truck in should have a very stiff mix and enough for the footings only. Get that mud in there and setting, take a little breaky-poo, then start with the next truck and begin filling the walls. Go around in 8-12" lifts and you're fine. We use a boom pump almost every time so it's easy to go 'round 'n 'round.

Dick Seibert
02-03-2008, 04:40 PM
Go around in 8-12" lifts and you're fine.
You must build one Hell of a lot stronger forms than I've ever seen, unless they are steel form systems, the most I go is around the house with 12" lifts vibrating all the time, to go full height like that you wouldn't be able to vibrate sufficiently enough to avoid all honeycombs. It's not hard, just keep moving around, on a 8' wall it's 9 passes around the home, and in mist cases here we only have to build the high walls on the back (or front) and halfway down the sides.

David Meiland
02-03-2008, 04:55 PM
Dick, I think we're saying the same thing.... ~12" lifts.

Forms are 1-1/8" panels with snap ties. The only possible blowouts on our average pour are at the corners. It is really easy to avoid them. I don't even think about it. I have never had a blowout, ever.... which isn't saying much since I only pour a few times a year and I overbuild the forms out of paranoia.

Dick Seibert
02-03-2008, 05:56 PM
David:

I had a blowout in 1980 in Orinda, we were building a new home on the existing foundation of a home which had burned down, the engineer had required all kinds of modifications to the old foundation as you can imagine, including drilled piers with sonotubes at times 8' high. In one section we were pouring against an existing bank with no way to use snap ties since there was only the braced interior form wall in one section and it blew. We had to let it go and come back and rebuild it the next day.

BTW, I told the owner that it would be cheaper to tear everything out and start fresh, but he was adamant because he had bought a lot with a foundation and swimming pool and he wanted to use them. It also greatly reduced permit time since we were "rebuilding a home" rather than building a new home, even though the new home was completely different from the old one.

Ted S.
02-04-2008, 03:26 PM
12" lifts? Common guys, the zipper goes in front. I go 36" with ICF which is like pouring concrete in a styrofoam beer cooler.

Ok, just kidding, thanks for the info on the mono pour.

David Meiland
02-04-2008, 03:38 PM
With ICF you don't have to strip and see whether or not there is honeycomb. A typical footing and stemwall pour for a typical house with ~2-3' walls is not time consuming, and going around a few times doesn't add much.

Tim Uhler
02-04-2008, 07:58 PM
Dave,

The last round of foundations we did, we made a deal with the old guy on the crew, Dave, I told him we'd pack all the materials, he could run the hose since we pumped them all.

He was the expert anyway. He'd fill up about 2' at a time around the foundation (basements). Didn't take much time at all at the rate the pump goes.

RobinNC
02-05-2008, 12:09 AM
Man.....I haven't seen wood forms for the footings in.....forever.....at least 20 yrs. Around here, they just dig out the ground with a 24" wide backhoe 12" deep and that is used for the forms. I thought that was the norm these days. One h@llava lot less labor involved.

David Meiland
02-05-2008, 01:29 AM
Robin, if you do it that way, do you dig again next to the 'crete if you want to install footing drains? The typical excavation out here is a big flat spot, bigger than the footprint of the house. Concrete guys have trailerloads of 2x6 and 2x8 they use over and over for footing forms.

Dick Seibert
02-05-2008, 01:40 AM
Dvid:

More than that, how does he get the code minimum 18" above grade without forming?

Lavrans
02-05-2008, 02:11 AM
Dick, he's just writing about footings, not the stemwalls, and I don't think he's doing thickened SOG type foundations.

Dick Seibert
02-05-2008, 02:29 AM
Lavrans:

Oh, I thought this subject was pouring foundations monolithically.

David Meiland
02-05-2008, 09:58 AM
Dick, in Michigan (where I hail from) I saw a lot of foundations done by pouring concrete right into a trench (4' deep +) and then stacking block on it. Think of it... NO forms.

Dick Seibert
02-05-2008, 10:33 AM
David:

That was tried here in the 60s by the cheap guys, there were all kinds of failures from soils pressures and the engineers would no-longer sign them off. Interestingly enough, I've never seen it in the tracts, who are about the cheapest imaginable, I think it's because the low end in the tracts was doing slabs.

Ted S.
02-05-2008, 06:38 PM
Dick, in Michigan (where I hail from) I saw a lot of foundations done by pouring concrete right into a trench (4' deep +) and then stacking block on it. Think of it... NO forms.

When you think about it, that makes sense considering that's how they install 50-60 foot deep slurry walls in the middle of Boston and build skyscrapers. They have to fill the trench with slurry so it doesn't cave in, then pump the trench full of concrete and displace the slurry. If you could get a nice vertical wall with a narrow bucket I think that method would produce a good product with much less labor especially if you can get some rebar in the wall.

RobinNC
02-05-2008, 11:07 PM
David....I didn't word my last post they way I should have. The 12" footings is the min for code but the backhoe guy will usually dig down around 18-20" leaving enough room for the drain. Only fill trench 12" deep.

Lavrans.....exactly.

Dick....probably close to 100% of footing are done this way in our area.(Charlotte, NC).....and they have been building houses here like crazy for the last 10 yrs. Track houses are almost always slab....cheapest way.

David Meiland
02-05-2008, 11:14 PM
dig down around 18-20" leaving enough room for the drain. Only fill trench 12" deep.

So the drain pipe is not at the bottom of the footing?