Window bucks
Last Post 30 Mar 2007 06:12 PM by icfblocks. 22 Replies.
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JohnCujieUser is Offline
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19 Mar 2007 09:34 PM
I'm going to begin building my first ICF house next month.  Using 6" BuildBlock for the walls.  My windows will be inset so I plan on  using a pressure treated 2x6 flush to the inside for a permanent buck and filling out the remainder with a 2x ripped to the outside.  Cleated together with ply and brace as needed.  Any flaws in this system?

Some windows are wide, eight to ten feet.  How do you make the bottom buck to allow for concrete pumping and vibrating?  I can only think of using a temporary bottom piece with cut outs for work and inspection.  Then install a permanent piece after the concrete cures.  Is this correct?

I have read and gotten conflicting advice on vibrating. I'm used to vibrating extensively with wooden forms.  My walls are 9'4'' tall. It looks a little awkward to snake the vibrator down thru all the web connectors as well as rebar.  Will vibrating the vertical rebar have any effect?  Can I put it on the foam outside? Or is it best to  be judicious and just sting it lightly? 

Thanks for any advice,  John
wesUser is Offline
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20 Mar 2007 08:05 AM
I would recommend using wider treated lumber for your bucks. We use 2x12 PT for bucks on our forms which are just under 12" thick out to out. Set flush to the outside, they provide nailers for installing windows and doors. The small area on the inside that is not covered by the bucks will be hidden by the jamb extensions and casing that is applied during the finish phase.
We always use 2-2x4 PT for the bottom buck one set flush to the inside and one to the out. This leaves about 4-5 inches open in the center for installing concrete under the opening. Once this area is filled with concrete, you can install temporary covers to hold the concrete in place while you finish pumping the rest of the walls.
I'm not a big fan of using vibrators on the walls. In the good ole days, say 10 years ago, when ICFs were new, most companies advised strongly not to use internal vibration because of the possibility of damage. We've always used a hammer and a block of wood on the side of the forms in the area being filled to consolidate the concrete. This has always worked well for us.
Wes Shelby<br>Design Systems Group<br>Murray KY<br>[email protected]
Cattail BillUser is Offline
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20 Mar 2007 08:55 AM
We gave up on pt it is to inconsistant we use Vinyl buck only on our projects and it works great we have also recessed our windows eliminating the extension jambs on the inside and placing them on the out side, this is done on our stucco homes we have not done this on a sided home yet. What we do is oversize the buck to allow for the addition of furring strips to be installed on the buck to attach the window flange to, we will be trying a flangeless window this year to help eliminate the extra labor of the furring strip. With the larger windows we cut out enough oblong holes (approx 18" on center) so we can fill under the buck easily and we can see in the hole where our concrete is at. Consolidating under the windows is done with a stinger in the oblong hole using short burst of a second or so until we have walked the concrete up to the bottom of the buck we then place the cut out piece back in the hole and scab over it or if using wood you could toe screw it in so we do not have any concrete exposed, this can be done regardless if you are using twisted sister lumber or vinyl buck.
Consolidation of the wall; if anyone tells you their wall does not need consolidation they are nuts, however again what consolidation is done should be in short burst not a heavy consolidation depending on your product and the block supplier should make a recommendation in this regards internal or external will work we use external on the wall with our wall banger placed on the bottom form every other tie and we follow the pumper around the wall about 4-5 feet behind, this is done at each lift height, and a final at the top off prior to screeding.
JohnCujieUser is Offline
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20 Mar 2007 02:03 PM
Thanks.  The VBuck idea seems pretty simple.  Will the vinyl hold screws for a 2x furring strip or do I need to attach to the concrete? Any idea of material cost versus wood?  It appears that labor is a little less.


John
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20 Mar 2007 05:07 PM
Another question.  Will I be able to bullnose the stucco on corners with the VBuck?  We are going for the adobe look with the recessed windows.

Thanks,  John
Cattail BillUser is Offline
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20 Mar 2007 08:27 PM
John this exactly what we do the vinyl will hold the screws just fine, you can also add for your comfort level a screw reinforcement strip where you will be attaching the firring strip this is a poly product of vinyl buck that slides in side the chambers where you want the extra comfort level.
We wrap the v-buck on the outside with foam board and slide it back along side of the window to the nailer flange this is attached with some plate screws, we also put a little PL300 construction adhesive for foam on the back side so it is both screwed and glued, then we wrap our poly mesh and apply our stucco, when you have completed this and the stucco is cured we caulk the gap to seal it and keep the bugs out and any potential drafts at our windows. We also attach decorative panels and corners as well as window reveals. As soon as I can I will send some pictures.
icfblocksUser is Offline
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20 Mar 2007 09:14 PM
Anyone that thinks anything but internal vibration I will be glad to forward a test done using several different forms of both internal and external vibration techniques.  Guess which one works.  If you  would like a copy of the report let me know and I will send it to you.  In my humble opinion if you are doing ICF work for a living and don't internally vibrate you are waiting for a lawsuit to happen. Only exception might be using some kind of "self consolidating concrete mix". It's too tricky and temperamental for me. 
Thanks,<br>Tom<br>www.advbuildingtech.com
icfcontractorUser is Offline
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21 Mar 2007 01:20 AM

John,

It sounds like you are getting some good advice here.  Tom you are right, I too have a copy of RD134 by the PCA, and the conclusion is external vibration albeit block of wood with hammer, sawz all with short blade, or large orbital sander type vibrator does nothing to consolidate concrete inside of ICF forms.  Internal vibration is the only recommended method of consolidation.

Now people should take a class on how to properly size their vibrator to the job and how to properly work the vibrator.  The ACI has a good class.  Because if you are running a vibrator in short bursts then you are not following the best methods and practices standard set by the ACI and you open yourself up to lawsuits.

I know of a house near Vancouver BC that had to be destroyed due to poor concrete consolidation.  Big Lawsuit.

ICF Contractor

JohnCujieUser is Offline
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21 Mar 2007 05:03 PM
Another vbuck question.  From the websire photos it appears that the vinyl projects a significant amount where it wraps around the foam blocks.  Does this produce a flaring at the opening when drywall is attached on the inside?  Any interior trim problems?  Rabbeting the back of drywall not a good option in my opinion.

Thanks,  John
Cattail BillUser is Offline
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21 Mar 2007 06:41 PM
This flange is very thin and is no problem when it comes to finishing, we place our sheet rock over it and it spans the little differanc there is.
Cattail BillUser is Offline
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24 Mar 2007 08:04 AM
Tom yes I am interested in seeing the info on RD134, and I realize that I can get the info for $20 from PCA but being the tight wad that I am I have a problem paying for some one to prove their point. Many of the test I have seen over the years are scewed to fit some one elses desired results and they will leave out any thing that is close to contradiction of those desired results and put in only the items that will confirm their desired results. You can either send the info to [email protected] or pass it along through this web site.
fjohnsonUser is Offline
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24 Mar 2007 01:44 PM
We're so proud of the way our windows turned out I can't help but do a repost on seeing the heading "window bucks". We used both treated wood and paper wrapped standard 2xs and 3/4 ply:

Here's how I did my windows.. on the 45deg windows I used regular 2x6 with roofing paper wrap and treated 3/4 plywood for 45deg sides and on the top and bottom.. on the 90deg corners I used all treated... 2x6's and 2x4's around.  Although it took 9 pieces of sheetrock to finish the 90deg. windows we're really pleased how they turned out.  Really enhanced the window look. 

On the vibrating.. sounds like many have had good luck with using outside vibrating (as we did, reciprocating saw w/o blade, up and down all the ribs).. and after having to punch through the wall for a fireplace that my wife couldn't decide where it was to go during building, I can attest to the fact that it is possible to achieve tremendous results in consolidation with exterior vibration.


PanelCraftersUser is Offline
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24 Mar 2007 02:00 PM
Wow, fj nice job!
....jc<br>If you're not building with OSB SIPS(or ICF's), why are you building?
Cattail BillUser is Offline
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25 Mar 2007 11:24 AM
I have now reviewed the info that you sent to me inregards to RD134 there is some very good info in this document but as I suspected it is not completely conclusive.
Lets take this one item at a time Sanders, blocks of woodw/hammer and sawzalls The study is very clear on there ability to do the job required. Unless maybe you are using the Tim Taylor Binford 6000 sorry just a little humor, we probably all have sanders and sawzalls and the amount of vibration they put out won't even give you a good back rub.
There is at least one other method of external vibration equipment that was not tested in this study, that being a tool called a wall banger that was developed specifically for this purpose. Another one that I have heard about but have not seen yet is a semi exterior and interior vibration system called rebar rattler I have not been able to find any info on this yet but will continue looking, this method makes some sense as the goal is to insure encapsulation of the reinforcement as well as the reinforcement being one of the items that dams the concrtete up.
Internal vibrators had a significant improvment over external but still allowed voids in the wall, so the actuall conclusion to this study clearly recommended the use of SCC or at min the use of add mixtures. and it also clearly did not recommend the addition of water to the mix.
Now lets look at the study it self as this is where I feel the study fell short,
1. the wall systems used where only 4" cavity where I am from I do not know anyone using a 4" wall other than the tear down guys. The min wall cavity is 5" and up to 8" for the average build especially below grade where we have high fluid density soils. The larger cavity allows for a better flow with less damming and I doubt any one will argue that point.
2. The placement of 2 #4 rebar side by side is the worst case scenario and not a very smart one. The better way if you have that extreme of a condition would be to use a higher tensile bar or a # 5 bar to accomadate the need for additional strength. The other item that I did not see or missed is the aggregate size used in this study, with a 4" wall with a 1 1/4 space blocked by rebar in this scenario that would only leave a 1.25" space on either side of the bar to allow flow of concrete with a 3/4" aggregate that would easily create major damming issues.
3. The info in regards to proper use of the internal vibrator was pretty good under those specific conditions but when do any of us have those exact conditions and the study did qualify that statement as being specific to the conditions that it was performed under as well as specify that the slump was also a major factor for the flow ability of concrete.
4. The next item that was talked about in regards to blow outs and/or bulges was also qualified by the statment of damage to the forms or it could have even been poor density and fusion of the foam.
Although this was good information I think the industry is a long ways away from the answers and the technology and the training that is needed to be 100% all the time, and I doubt we ever will be 100% but is a goal that we should shoot for.
In a final note PCA also qualified that this study was based on the opinions of the author and given the test preformed I think they are good opinions. Hopefully there will continue to be studys done that incompass new technology, equipment, products, methods, and training. Because I for one want to insure that my customers receive the absolute highest quality home available!
fjohnsonUser is Offline
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25 Mar 2007 12:49 PM

Thanks PanelCrafters......

on consolidation... this authors opinion after punching the fireplace hole and removing inside styro for several ledger boards and electrical outlets is that a 6.5 slump and external vibration will get you a good product.. mind you.. this is my opinion and I will say that if I ever build another concrete home.. it will be done the same way..

now, going back to the window bucks we're so proud of.. here is a variation we did on the french doors that only used 6 pieces of sheetrock and then wood casing/extension jamb.. turned out real nice too.

James EggertUser is Offline
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25 Mar 2007 01:09 PM
fj
nice details

I also use untreated felt backed 2x for my bucks above grade, although I use a treated 2x4 for the exterior of the bottom sill.
Take Care<br>Jim<br><br>Design/Build/Consulting<br>"Not So Big" Design Proponent
icfblocksUser is Offline
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26 Mar 2007 10:28 PM
Bill,
I have a re-bar shaker. I will say it works a little better than the sawzall. But I still would not bet my continuing reputation on it. I will stick with what I am sure works. We do it all the time without trouble.
Thanks,<br>Tom<br>www.advbuildingtech.com
icfcontractorUser is Offline
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27 Mar 2007 12:39 AM
Hey Cattail,

I am glad you read RD134 but I think you may want to examine it a little closer.

1. the wall systems used where only 4" cavity where I am from I do not know anyone using a 4" wall other than the tear down guys. The min wall cavity is 5" and up to 8" for the average build especially below grade where we have high fluid density soils. The larger cavity allows for a better flow with less damming and I doubt any one will argue that point.
Look at table 1.  They did use 4" flat panel as well as well as 6" flat panel, waffle, a screen grid.


2. The placement of 2 #4 rebar side by side is the worst case scenario and not a very smart one. The better way if you have that extreme of a condition would be to use a higher tensile bar or a # 5 bar to accomadate the need for additional strength. The other item that I did not see or missed is the aggregate size used in this study, with a 4" wall with a 1 1/4 space blocked by rebar in this scenario that would only leave a 1.25" space on either side of the bar to allow flow of concrete with a 3/4" aggregate that would easily create major damming issues.
I don't know where you build at but I am in seismic zone D and the minimum rebar requirement we have is 2 #5s for our tension bars in the lintels and depending on load 2 #4 or #5 for our compression bars once in awhile we will get a single top bar and then add stirrups to that.  All grade 60.  Also if you read about the concrete mix they tell you in all cases they used 3/8 pea in all of the mixes.

3. The info in regards to proper use of the internal vibrator was pretty good under those specific conditions but when do any of us have those exact conditions and the study did qualify that statement as being specific to the conditions that it was performed under as well as specify that the slump was also a major factor for the flow ability of concrete.
Bill I don't know if you have taken an ACI (American Concrete Institute) class on proper consolidation of concrete but what they were quoting was not some ideal labortory condition but actual information from the ACI on how to properly size and vibrate your concrete in the field under actual construction conditions.

In a final note PCA also qualified that this study was based on the opinions of the author and given the test preformed I think they are good opinions. Hopefully there will continue to be studys done that incompass new technology, equipment, products, methods, and training. Because I for one want to insure that my customers receive the absolute highest quality home available!
I must have missed this, I can't seem to find where the PCA is trying to qualify there findings as opinions of the author.  Maybe you could tell me where.

The conclusion states word for word.  "No clear distinction immerged among the the external variants of mechanical Vibration (hammer, orbital sander, reciprocationg saw).  All three methods provided limited consolitation, but did not efficiently transport the concrete past reinforcement steel and generally resulted in significant voids"...  It basically goes on to say that internal vibration works only as well as the person operating the vibrator but it held the most promise.

As for your rebar rattler I think the last thing I saw was the ACI was against them, because they do not remove any air out of the concrete.

ICF Contrator



Cattail BillUser is Offline
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27 Mar 2007 08:03 AM
Like I said I have not found any info on the rebar Rattler so if you know where that can be found let the rest of us know.
Look at the first paragraph of the acknowledgements on page 13 in regards to the PCA position.
I do not live in a seismic region and do not pretend to know any thing about the rebar requirements for your situation, we also use 2#5 sch 60 over our lintels, the rest of the wall we use #4 bar and the only place that we lap is at the joints and that is done according to perscriptive method, and this area does get extra attention.
I did miss the 6" info in table 1 probably because the 4" caught me first, but after reveiwing this I did notice the info in Table 1 however in the proceeding figures and documentation I still do not see which photos or figures show the 6" info. When it comes to the waffle grid well lets just say I do not think that you can efficeintly pour a waffle wall without voids which is why several of the manufacturers of this type wall know offer a straight wall also.
What I was refering to on the internal vibration was not in regards to the vibrator use but to the vibrator use in this study, and that shows clearly that the internal even though it did better than the external still did not get rid of all of the voids and that the SCC was the absolute best item to use based on the results of this study.
Ian with ICF BuildersUser is Offline
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28 Mar 2007 10:28 PM
We have six multivibe gas powered vibrators with whips 8' and 10' and 1" head...these will go down in a wall no matter how much bar you have...we typically run #5 bar vert at 12" on center and #4 on 16" on center and much more lintel steel....voids are a thing of the past if you do the work correctly....We also have electric models from Dreyer vibrator, the best electric model on the earth. We use a large head for vibrating the window sills (we pour all concrete from the top of wall and use two 2x4's across the bottoms of the windows..once the window sill is fulll, we use a "jam block" to stop the flow of concrete into the window sill. We also typically place concrete in 6" forms at a rate of 1 yard per minute or a ten yard truck start to finish in no more than 15 minutes. We use better form systems and don't worry about blow outs or crooked walls. January and February, we poured nearly 100,000 sf of form and also set over 100,000 sf of Hambro floor systems.....rarely are any of the crew concerned about blowouts. BTW, we also use site added plasticers on these types of projects. Building with ICF is no different than riding a bike for the first time.....all your friends that already knew how to ride told you "it's easy".....did they tell you what you had to learn the hard way? The whole idea of using inferior ideas such as sawzalls, sanders and blocks of wood and hammers demonstrates a true lack of knowledge about proper methods....akin to a doctor using a sledge hammer on one's knee to see if your reflexes work correctly...Why does this topic and these absurd ideas keep coming up? The mere discussion of such methods continues to prove to the major concrete and related industry companies that the industry is still filled with a bunch of yahoos that think they understand more than what they really do.....

Would you hire a body shop man to take dents our of an expensive vehicle if you walked into his shop and saw him throwing bean bags at dents and from your questioning look he states "this is the best way to take dents out" ??? How many potential ICF consumers and converts watch the "chinese firedrills" and walk away shaking their head stating to themselves..."not on my project"?? My bet it is way more than most of you can imagine. The better form systems can handle internal vibration, start using those systems and let the inferior ones die so that the whole industry can gain from the step up in professionalism. Additionally, learn the trades that encompass the product that you are selling. There is a longtime frequent poster on this site that just recently told a person that is building large condominiums in Oklahoma City (this guy is from out of town, his price and speed rewarded him the project) that he was bringing a lawn chair to the next pour so he could watch the methods that the installer employed (that we know work) fail.....The lawn chair and person were gone soon after realizing that he was wrong......how does that stuff look to the outsiders? Why doesn't this industry MOVE UP? How can the guys in Omaha make a decision not to vibrate? This stuff further makes outsiders say "They have a long way to go before they build my project"
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