How do you handle your bracing? I know that you can get special icf braces, but does anyone use them, or just use lumber to brace. I don’t think there is anyone around here that would have them to rent.
What about pumping, did your concrete company have a pump, or did you rent?
Same with vibrating, does it need to be vibrated, or can it be poured wet enough to just tap on the icf’s?
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Replies
heres a site where you can buy some things made to brace with icfs.http://www.wass2.com/
you can probably brace with 2x's but a brace system would be much better.someone will be along that has probabaly 2x4 braced one and gicve you some ideas.larry
if a man speaks in the forest,and there's not a woman to hear him,is he still wrong?
nater,
One of the reasons I went with Reward forms over others is because they had free use of the bracing/walkway. Return them clean and there is no charge.. However I didn't use their bracing for the front bow/portico.
Because I cut each form into three pieces in order to form the curve I used wood to join the pieces together. I didn't need a walkway either because I back filled before I poured. Do it gently and you not only get away with it but it provideds the bracing.. floor joists provided the resistance to inward collapse and I was able to make a successful pour very easy. The pump operator refused to pump unless I put interior braces in so I did but I left them loose just to prove to myself they weren't needed.
I also poured the footings and the walls at the same time! (not reccommended)
You should have a vibrator but I found that instead of the vibrator I added a gallon of the self leveling additive to the mix about 5 minutes before the delivery truck dumped into the pump. That stuff makes the cement flow like water and eliminates completely any possiblity of air pockets.
But I wouldn't attempt this without the experiance I gained and those unique circumstances. I'd use the bracing/ walkway they provide. I'd follow the procedures they have in the manual.
The cement companies all have pumps of various sizes.. because I needed to work in my driveway I had the small trailer mounted one. That's more work than the boom pumpers. Boom pumpers don't need to lay out the delivery hose and you don't have to drag that heavy hose around to fill the forms. they dangle it over the forms as you pour and it's much easier, but it wouldn't work on my jammed site.. the delivery trucks took as many as 9 cuts backwards and forwards to get into my driveway ( and even more getting out)
I'm having a hard time understanding how you could backfill the hole to hold the forms and pour the footings at the same time as you poured the forms. Wouldn't the backfill fill the footing forms?
Also, how did you connect the floor joists to the forms prior to pouring the walls? Did you put in the sub floor prior to the pour as well?
Thanks,
Bruce
bruce,
Not if you cap the footing forms.. (which I did)
Let me see if I can give a better description of what I did. My footing forms were 24 wide by 24 deep. I installed the required rebar and then capped the outside of the footing forms. I cut 24 inch spacers to seperate the tops of the footing forms. they were installed flush with the form while the caps sat on top of those spacers holding the forms firmly in place..
Thus concrete was free to fill up the footings and once filled go on up and fill up the forms.. the forms were held in place by the caps.. Now the caps were made of pine which I left on the outside to decay.. the spacers were white oak wrapped in poly and thus decay resistant.
Upon completion of the pour the concrete which quickly stiffened enough for me to remove the forms on the inside and verify that no air gaps were present. (there weren't) Seing the inside free of voids I took it on faith that there would be no voids on the outside which had been backfilled. Since I watched the concrete flow in like water with the self leveling additive I had every reason to believe the soundness of my technique. I removed the form work for the inside and poured my floor.
Yes I did install the floor joists prior to the pour.. They sat on the wood which joined the small form sections together.. with lag bolts (stainless steel 1/2 x8") projecting into the form (and concrete) Rebar was tied to those lag bolts as were the J bolts which held the plate in place.. The joists were used for the decking which made up my portico. The decking didn't go on the joists untill after the concrete had been set. (screwed not nailed so minimal impact).
The "basement" space in between is used to store dock sections during the 7 months of the year they aren't in use on the lake.
Thanks for the very good description. I get it now, but have another question. Was the exterior of the wall waterproofed prior to back filling? Wouldn't your method cause a potential vulnerability at the corner of the foundation and wall. It is probably minimal since it was all poured at the same time. Around here with clay soil and high water tables, it would be a concern for me. However, I like the idea of doing it all at once and needing the pumper only once.
Bruce
Bruce,
I dealt with the new work old work issue by drilling holes in the old work for the rebar as well as some 2 inch holes just to key everything together better.. Ya gotta love those new hammer drills!
As for water proofing, I didn't care because the space under wasn't living space just dock storage (yes the floor is slightly sloped so should any water find it's way in it can darn well find it's own way back out <grin>) If It had been living space I could have easily water proofed it prior to back filling .
PS I hand back filled it. 6 inches of stone first then drain tile, then more stone on top of the drain tile.. finally carefully shoveled dirt. Yes it's heavy clay, that's why the oversized footing. Once the cancrete had gained it's full strength I really packed the dirt down and then did final landscape grading..
Frenchy
I didn't need a walkway either because I back filled before I poured.
I did that too on much 1st ICF, and addition with a crawlspace. Footing were poured 1st. Forms were 4-5' tall.
We backfilled alittle to set the bottom of the form. We alittle turned in to filling them up 1/2 way.
Every thing looked good so we went home for lunch. Came back to the forms collapsed whereever the sun was able to hit the plastic spacers. Where the sun didin't shine on the spacers everything was fine.
What a mess.
Rich
Edited 4/1/2008 3:23 pm ET by cargin
Rich,
Wow what cement did you use? Mine was stiff enough to pull the footing forms within 15 minutes of completion of the pour. The pour took less than 1/2 an hour.. So about 45 minutes from the start of the pour I was pulling off forms..
When I did my first piece I did everything the way they called for using the walkways, bracing. etc. and yet I got a 3/4 inch bulge. That was my error because I tried to pour one corner completely rather than drag the hose back and forth. I took most of the bulge out with a chunk of 3/4 plywood and some bracing. But I could see it stiffening up so I left the final 3/8ths of an inch in and went ahead with the rest of the pour.. That part wound up in the entryway closet so you really can't tell..
I learned the trick about the self leveling additive on a latr pour and I really like using it.. it's kinda magic.. flows like water and then stiffens up immediately..
Frenchy
I did some back fill before pouring. Before ICF blow outs were out main concern.
We were working in a trench building the forms between our legs.
We put alittle dirt on each side to hold the bottom courses in place.
Well alittle dirt turned into backfilling 1/2 way up. No problem until the sun made the plastic soft.
This was 7-8 years ago.
Rich
Cargrin,
I guess you have me lost, The plastic spacers I've seen are all molded into the forms, So not exposed to any sun and they are a crosslinked polyurethane not really a plastic but that's a small nit to pick.
All of the spacers I've seen at shows and displays are white or a whitish color anyway unless they are steel which I've also seen.. Now AFM made a plastic piece designed to use straight foam panels that was a colored plastic but those can't really be considered a ICF since they are just panels of foam and not true forms..
I looked at those and commented, "now that's a blow out waiting to happen".. (and I used AFM's panels for my SIP's)
What cement mix did you use that flowed so freely after wards? Every pumpable mix I've ever seen starts to set up rather quickly after it comes out of the hose.. I mean you did read where 45 minutes after I started pumping mine was set up hard enough to pull the wooden footing forms didn't you? That sort of time factor seems relatively normal even flat work I see them pulling forms relatively quickly and I don't think they would have any additive in flatwork..
102914.13 in reply to 102914.12
Frenchy
I did some back fill before pouring.
Before ICF blow outs were out main concern. I thought a little backfill will hold it all together.
We were working in a trench building the forms between our legs. Walls were 4-5' high.
We put alittle dirt on each side to hold the bottom courses in place.
Concrete was to arrive the next day
Well alittle dirt turned into backfilling 1/2 way up. No problem until the sun made the plastic soft. The plastic ties got soft and the form collaped inward. No concrete was involved yet. The sun was right overhead, mid summer.
One wall was shaded by the house and no problems holding back the backfill.
We had to dig out the sides of the forms and push them back out, and in some cases tear them out and start over. All 24 hours before concrete arrived.
This was 7-8 years ago.
Rich
cargin
Thanks for the clarification.. it's obvious what I thought.. so techically you had a blow in, <grin>
OK I think I follow you now, but what brand of form were you using that collasped under sunlite? What sort of temps are we talking about? What sort of soil?
Yes, that had to have been a real mess. I can't imagine how to do that with the rebar already in place etc.. The forms I see are all interlocking so disassembly would have been an absolute nightmare let alone reassembly with some structural regidity.
In my case the rebar made the forms so strong that I suspect I could have gone ahead and pumped without any bracing.. (don't forget this was in a giant bow not a flat wall)
frenchy
They were Lite forms, with an interlocking (castleted top) orginally called fold-forms. Lite-Forms make two different kinds. I have used them twice since and they are wonderful. No foam, just stack them up and they pour straight and easy.
They have a reinforcing web that laying in horizonally, every 4 ft or so. It looks like a #9 wire floor truss 7" wide. That straights the wall out like an arrow. if I was doing a big pour I would use them more often then recommended. They were not very expensive.
I sure appreciate you allowing me to air my mistake out for a long a possible. Hey what are friends for anyway.
Rich
Cargin,
Thanks for sharing with us, I realize it's embaressing but it is also helpfull. Others might get the idea that back filling with dirt is an easy sure thing way to do things . While that happened in my case as you very kindly pointed out it's not always going that way..
holy cow
Beer was created so carpenters wouldn't rule the world.
If you're pouring a high wall, say 6' or better, your bracing must be adjustable because the forms will tend to move out of plumb as you pour and the factory forms have that capability, or you can use "masonry jacks" which are turnbuckles that you attach to 2 X 4's and can be rented or purchased from a masonry supply.
The best vibrator for ICF's is a 1" needle gun which is an attachment available with vibrators at most rental supplies.
If this is your first experience, the ICF supplier should be providing you with training materials or a class and an on-site factory rep to guide you with assembly, buck construction, utility penetrations, bracing and the pour.....not a full time helper, but a "mentor.
I have done both. On my first pour, the manufacturer called for basically building a 2x4 wall with studs 4' oc on both the inside and outside of the forms. That was a lot of monkey business.
Now we rent braces. We rent them from a concrete/masonry supply company, but they are also available from the redi mix company. Anyone who sells ICF's should be able to help you find them.
You COULD make your own of a similar design out of 2x4's, but it would be a lot of work both putting them together and taking them apart. The 2x4's are theoretically reusable, but would be full of concrete, if you included a walk plank bracket you would cut up even more 2x that wouldn't really be that usable afterwards.
Factory-made ICF braces have slots for the screws into your ICF's. This allows for the forms to settle as they are poured. They also incorporate a turnbuckle--we have our forms leaning in slightly, and right after the pour we push the wall out to a string line. That is because if the wall is out, you can't pull it in with a brace--can't move a wall of wet mud with a drywall screw into plastic! If you make your own, you better incorporate some sort of adjustment.
Of course, the above advice is for basements. If you are just pouring a short stemwall or something, you have a little more leeway.
Considering the investment you have in the forms, renting braces seems worth it to me.
Just saw the rest of your question...
We hire a pumper separate--that is just way it works around here. Call your redimix company and see what they say. They might even have a conveyor truck.
We don't vibrate, nor do we know any masons around that do. We have two guys going around with a 3' block of 2x4 thumping the forms as they are poured.
Re: pumping, I read recently that many pumpers have 4" hoses but a 3" hose works much better with ICF.
I'm hoping to do my first this summer.
I completed an ICF basement last year using 2x4s and standard turnbuckles. As far as bracing goes, it worked okay - but my biggest problem was related to accessing the tops of the forms during the actual pour. It required a lot of scaffolding for 9 foot walls. As you might guess, putting up the scaffolding got in the way of the bracing at times. It also required double the effort as I had to install two separate systems. Based on my personal experiences, I would try and get access to the commercial ICF bracing/scaffolding systems. They will save you considerable time and labor, be safer to work on during the pour, and result in a better product in the end.
As far as backfilling before the pour so that you can access the top, I wouldn't even think about trying it if you truly want perfectly plumb and level walls. The ICF will need to be adjusted during the pour, especially for long straight walls. The more bends in your foundation, the better as far as reinforcement goes. [Oddly enough, I had designed my house and foundation to save on concrete and ICF costs -- perfect rectangle, almost square -- but failed to realize that those long straight walls added extra cost for the additional 2x4 bracing required .]
My 2 cents as an amatuer homebuilder.
bigkoiguy,
I used the commercial ones supplied by my vender and once the pour was done only needed a tiny adjustment +or- 3/8ths of an inch maximum.. on a wall 38 foot long.. the short 16 foot lengths stayed within a 1/4 of straight. Rather than wrstle with the turn buckles etc.. I just shoved a block of the appropriate thickness ply wood in place..
None of my other pours were as long and I never got a chance to do the whole foundation at once..
I will say that when the concrete first thundered into those forms it scared the bejesus outta me but as long as I didn't fill more than about a form level high per pass everything stayed pretty straight..
Later the pump operator got a remote control box to control the rate of pumping and that turned it from a scary proposition into something real easy and smooth.
I notice the crews using those remote control units were a lot less frantic and nervous too,, pours just went easier..
The bracing not only makes it easier to pour, but easier to stack the top few courses. At $1k a month rental we think it's a bargain. We also use it to set the floor joists.
If you don't vibrate to consolidate the concrete it's possible to get substantial honeycombed areas. I wouldn't dream of pouring ICF's without it since there are so many corners that concrete has a hard time working into.
The exception is when using a very low slump mix with small size agregate. Many areas allow these pours and many don't since it's easy to misjudge what you are doing and have major problems.
Guys cutting corners with ICF's end up with snakey walls at best. Even average contractors building with ICF's typically have crappy walls--just ask any concrete pump operator and he'll tell you dozens of horror stories related to poorly thought out ICF pours.
The 3" hose does work better for narrow forms, but for 8" and larger forms I'd rather have the normal hose since it allows for faster delivery and pumps a stiffer mix more easily.
Backfilling forms prior to a pour is wrong in so many ways I'm surprised to even hear it. Proper water proofing the exterior would be impossible not to mention any uneven pressure on the forms will cause ripples or waves in the wall. When that happens there's no way to fix it since it's not practical to push against a backfilled wall.
ARXX forms expand nearly 1/4" when loaded with mud so any backfill would force the wall inward.
Beer was created so carpenters wouldn't rule the world.