I’m looking into using ICF for the first time on my next project. Does one assemble a 24′ wall from footing to top sill and create a monolitic pour in 6 lifts or are foundations set-up first and only then walls assembled? Bond beams between levels? Are cold joints OK?
Is brick veneer gapped as with framing or flush as a parge? Has anyone used foam forms for horizontal work as a floor deck planking or as one manufacturer shows for roof deck?
I’m willing to learn from others’ experiences (mistakes). War stories appreciated.
Replies
thad, You can pour the whole wall or you can break it down into "floors" . I did my basement then put on the floor deck then my walls for the first floor and parts of the attic. The outfit I got my forms from showed walls up to 30' in there info. I added the brick ledge to the outside of my form. So I had a 4" brick ledge 4" foam 10" comcrete and 2" foam then 5/8" drywall. Don't know about using foam forms for floors . Don't think I would want to try it. You try it.
Don
In my experiance, (i used ICF's for foundation) I'd be afraid to rely on poured or pumped concrete to have much strength without the compression of weight to aid in compaction.
I had to do some work which required removal of the foam from a section of the forms, In spite of vibration and "thumping" There were a number of sizeable air pockets in walls that were 18 inches thick. Now in the big picture They didn't affect in any structural way the strength of the walls, but it would be easy to see where on a flat pour like decking there could be the potenial for failure.
Every concrete deck I've seen is made with prestressed concrete. That is they pull steel cables under tension in a form and then pour in the concrete. once the concrete hardens they cut the cables which effectively "pulls" the concrete together.
Frenchy - yes the invisible nature of what's happening inside most ICF's would make it too spooky for horizontal work. But Poly Steel http://www.polysteel.com/paneldeck.html has forms that are open. Has anybody seen those used?
Don - which ICF did you use and did they have a brick ledge system, or did you have to field modify? Did you gap at all behind the brick or was it in direct contact with the ICF (no special flashing or weep system)? Also, between the foundation and wall system, was there a cold joint inside the ICF or did you use some intermediate step between the two levels?
So far I'm liking what I'm hearing about this stuff. Has anyone used several brands of ICF and formed any opinions or preferences?
No problems, only opportunities.
thaddeus ,
I used R-FORMS ,It is a panel (4x8 extruded polystyrene) that you make up yourself from exp sheets ,16 spacerties 16" o.c. It makes a very open form sothat any type of concrete can be placed in the form. I used a conveyer truck to place a regular 6bag mix at a 5" slump. Iused metal studs to make wailers and stiffbacks for my forms ,run hexhead snapties at 32" o.c. into the stiffbacks. short walls need wind bracing tall walls need a lot fo wind braceing. The company that I got my system from has gone out of buisness . I would recomend that you find a system with a open webing to space the forms,less chance of a conrete bridge forming . I would not use the forms that make small pillars and beams . Look for forms that use plastic ties ,to eliminate the thermal bridge you get with the metal, I used a wooden stick to rod my walls ,that and the concrete dropping more than 6' from the conveyer down the trunk and forms was all the viberation that I needed. use open bottoms on your window/door bucks so that you know that the concrete is in place under the door/window. Don
thaddeus raven,
To answer your question about ICF deck, I've seen samples of the product but have yet to see it used. However a guy that I worked for a few years ago, and still keep in contact with, is using a ICF deck product called Insul-deck, he raves about the product.
I had a chance to work a few jobs of ICF installation. The ICF we used was Techblock, you can check it out at http://www.holdfast-tech.com (I think they changed the name to Safe block) At the same web site you can also check out Insul-deck.
Also you were asking about brick ledges. With Techblock the footer pieces (you will see on the website) can be installed upside down at any level in the wall to create a brick ledge.
Scott R.
Edited 5/17/2002 8:45:43 PM ET by Scott R.
I used Poly Steel forms for an 11' high wall. did it on two separate days - but not because we wanted to. Got a bad batch of mix in second truck. Which leads to the following: Do not pour when the temp is over 90 and the sun is in a cloudlesss sky. Do not let the ready mix co. give you a load of mix that has been in the tank for 30 min plus because the driver got lost. Do not accept any mix that does not meet proper slump. I was SCREWED royally because I had a contractor do the pour and I chose not to interfere till it was obvious that everything was going to Heck in a handbag. Actually, I didn't have to squawk much - the pump froze up and they had to quit work. Took them 2 days to clean out the pump. I wound up w/ some humongous voids - some as big as twice the size of a man's torso. Learned how to make windows in forms, remove rubble and refill w/ precision grout.
Rodding didn't solve the problem of a mix that was curing as it fell down the forms.
There is a contractor in eastern Alabama who cuts windows in the sides of the forms at about the second or third level, fills the lower sections, sticks the cut out pieces back in w/ glue, and fills the rest of the wall from the top. He also uses a superplasticizer. Claims it makes it easier and less messy. The local Poly Steel rep shakes his head with wonder, but admits that it works quite nicely.
Contrary to advice about more bracing required than advertised, I talked w/ several contractors who use about half the bracing required by the ICF mfg's. I followed their lead, and had zero problems w/my 11' wall. Not even a hint of willow tree wiggling. While putting up the forms and bracing them, I kept reminding myself that I was pouring concrete, not molten lead. That concrete is viscous and gets even more viscous as time passes. If your slump is correct, you pour at the rate they recommend, and do it in the lifts they recommend, by the time you start on any succeeding lift, the previous will have considerable stiffness and not be prone to leak unless the forms are weakened for some reason.
Next phase of my house, I'll pour myself. Having watched and remembered the first experience, it is not rocket science - but I'd not recommend DIY the first time w/o watching several pours first.
DonThe GlassMasterworks - If it scratches, I etch it!
Thaddeus,
You can pour it all in one shot or pour lifts, each has advantages and disadvantages.
I don't know about 24' because the highest I've gone in one pour is about 11'. I might be a little concerned about that much height.
One advantage to multiple lifts is you can drive 3/4" steel pins at an acute angle a couple inches down from the top of each lift and hang scaffold brackets, enabling you to set and pour the next lift. You just drive the pins as soon as the concrete starts to set up, twist them a few times over the rest of the day so they don't stick, pull them before you go home that night, and the next day put them back into the holes and hang your scaffold brackets.
Cold joints are not a problem as long as the rebar is right. Just leave the concrete rough. If you're really concerned a slush coat of anti-hydro and portland cement will provide a better bond.
The best tip I can tell you from experience is you will probably need more bracing than the manufacturers will tell you. Brace your window bucks so they dont rack or deflect, and brace against wind loads on the unfilled walls. Atr anything over 8' these walls get real wiggly when they're full of wet concrete. Better safe than sorry.
As for concerns about unfilled block, just use a 3/8 pump mix with a superplasticizer and there's no reason at all for a problem to happen. As I fill the forms I have a laborer follow me around with a piece of rebar and rod down the material. That definitely works, because sometimes we do find pockets. I doubt if I'd vibrate it, the rodding seems to suffice.
Figure out how many yards of concrete are supposed to go into the forms and make sure it does. Your pump sub will tell you how much you'll lose to the pump and hoses.
As for decks, Reward also has a product, I think it's called C-deck.
DRC
Thanks All;
Good information. Now can anyone recommend ICF in Massachusetts?
One point, do not try to pump your forms with out several strong and smart people handy. If everything goes well you won't need them. If a problem developes, you need help now, like right now!
During my pour the truck driver kept leaping onto a brace to get to the top of the wall. I didn't notice it but the brace pushed the wall in too much and I almost had a blowout. Quick action kept it from total distruction, but there is no way I could have dealt with that by myself.
One final thought. how fit are you? Are you capable of wrestling with that hose while concrete is pumped? It's heavy and wants to throw you around. I admit That inside of 10 minutes I was knakered. If I didn't have someone to relieve me disaster would have resulted.