Is there a practical limit to how short a block piece can be in a wall? I've started to lay out blocks for my walls in my CAD drawing of the house I'm getting closer to building. I have a combination of short wall lengths and window sizes that is going cause me to have block pieces as short as 6" or less against some window and door openings. Am I asking for problems with block pieces this short? Should I reconsider some of my window sizes and/or locations so that I will have longer cut pieces at the openings?

First of all I would get rid of the cad program. With most forms you will need to cut a splice plane in the wall to make up the difference in measurement between your wall length and the layout size of your forms. We try to put this splice plane above a door or window or near the center of the wall. The minimum size of a cut is usually 3 to 4 inches beyond the tie. or as we would say a 3-1-3. This size can be placed freely and stay in bond with our forms. Forms with only 1" passed the tie can also be used , by matching with a form that 5" on the other side . Some spray foam or strapping will be necessary. We place non standard forms like this on the inside walls at a easily reached level in case some rasping is needed. This is our wast management course and marked on the wall as such.
You will not want to put such cuts around door or windows or in columns. If you are not comfortable with this technique then just measure foam at the end of your block to the tie x 2 pluss your tie wight and that is as small as you will want to go. Remember your waste foam can be used over window headers.

Thanks for the response. Maybe I wasn't as clear as I thought I was. :-)

One situation in particular. I have a wall segment 12' long from outside corner to inside corner. I'm planning on a 5'-3" wide window which means the block opening will be 5'-7". On one side the long leg of the corner block comes to within 5.5" of the window opening. I will need a 5.5" long piece of block to fill in there. On the next course the piece will be 1'-5.5" because of alternating the long and short legs of the corner block. Naturally, every door and window will have less than full length blocks adjoining it. My question is should I adjust my wall layout or window sizes so I don't have such short pieces adjoining a door or window opening? How short can those adjoining pieces be, and not needlessly buy potential blowouts, or other problems?

As for the CAD, I recognize that the blocks aren't going to come out exactly as on the drawing, but they will be close. I do plan to make up the difference at a door or window. I'm also planning on laying the blocks from each corner, working to an opening near the middle of the wall and making the adjustments there. Actually, I'm using the CAD to come up with the scheme for laying out the blocks in the best way because I know they won't fit. I set all the wall dimensions on 2' increments at the inside surface of the blocks. With BuildBlock corner blocks having a length of 1'-9" and 2'-9" there ain't no way full increments of blocks will fit an entire wall length anywhere!

Don't bother changing anything at this point. The dimension issue you are referring to would be problematic with any ICF. Many form companies would simply zip tie the short piece to the long leg of the ICF corner. We don't recommend zip ties at all and would simply glue this 6" piece in depending on how your bucking your window. Many things can happen at corners with windows close by but we need to know how you bucking?

Dave

I'm planning on using 2 x 12 ripped to 11" and spanning the full thickness of the wall. I was going to use doug fir with poly or roof felt to separate it from the concrete, but my civil engineer cousin, who has 40+ years with concrete construction design experience, suggested otherwise. He said I don't need the strength and quality of DF in this situation so to save money he said I ought to use hem-fir 2 x 12 and lather the concrete contact side with emulsified asphalt. Sounds good to me. I plan to glue the block ends to the buck and may nail something like a 1 x 4 on both sides of the buck to form a flange, maybe not the entire buck perimeter but at least about a third or so, and the corners for sure. That'll hold everything good and tight while we pour.

V-buck looks nice but I'd rather input my labor than pay the price!

If you are going to use wood bucks with small pieces of block as you spoke about it will be time well spent to use 1 x 4 around the buck to hold help everything in place.  On the short pieces, 6" it helps to have a tie in place in the piece.  It's not always possible but it sure does help.  Very short corners are also a good place to take extra care with bracing and scabs to hold it all together. 

Thanks for the comments, suggestions, and reassurances.

1" x 4" is the worst thing to use because it splits. Watch for a local job site and get there scrap OSB, can't count how many footing spreader's I have seen blown on jobs with 1 x material. Now that you are using a full window buck,(outside to inside flush) you can use the osb at those 6" pieces cleat ed horizontally from window buck back to at least two ties on the corner blocks. This will solve your short piece issue and with a 6" o.c. tie block you will have a tie anyways.

On another note if you have any full block from one window finishing with a small piece as above here's the solution. Take the last full block out put in a 6" piece (usually from scrap) then finish with the full unit. This gets that small piece away from the buck. Off coarse we do this because we only do inside bucks which we find to be much superior.

Dave

Sorry you have so much  trouble with 1 x 4.  It works for us when needed.  We find osb  tends to flex when used as a scab especially when it gets wet.  To each his own.  There are as many ways to solve a problem as there "experts" on the Forum. 

Tom, It can't flex with an inside buck!

Dave

Dave,
How do you fasten windows in place with an inside buck, with jamb clips? One reason I plan to use full width bucks is to have the wood to fasten the window flange and the inside trim. Am I missing something? Or is this mostly another case of "to each his own?"

Mac

Mac : yes, to each his own. LOL

         Using the exterior foam for thermal break is a good method. Using jamb clips work, and having the buck flush with the interior
          helps for trimming.

         We use a lot of "nailing flange" windows, as they seal to the foam or buck with a bead of silicone, and are very fast to install.
   
         Tip, we attach brickties to the back of all bucks so that they embed in the pour and make attachment.

         There are dovetail anchors out there also you can use.

         Like the boys say, there are 10 different ways to achieve the end result...all good.

          Our shortest piece of block in any wall is one web. For us that is "4 inches" . When I see a weak spot being built,
             I'll replace 2 bars of foam with a web.

           I'm with Eldon on the CAD program, no matter how good it is, you will have site adjustments  for sure.
         
           Don't spend a lot of time on it.

           To us a "splice plane" is a total waste of time, we maintain block interlock priority and adjust building measurements.

           In this day and age, if a designer can't design to the block's modular sizes, he is not competant in our humble opinion. LOL
.       

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mac
forget the "emulsion" bs, for a few reasons, just use 15 or 30# felt in about an 7-8" width stapled onto the buck.

As to DF vs Hem, I wouldn't worry about either, however I wouldn't use hem fir just to save money; just don't use spruce, which dries and twists later.

And although you can order KD DF and KD Hem, the typical moisture basis for above grade walls to me doesn't make a diff.

Also, assuming your lumber will be 11 1/4 to 11 1/2" and it appears you are using an 11? system, I wouldn't cut down a 1/4", just favor the buck to the interior, and a month down the road, if it hasn't dried and shrunk that much, a quick plane will flush it out.

I use DF bucks but always a pt 2x4 at the sill exterior. If years down the road something is to go, thats where it'll happen.

We have used all sizes just glue it or do what ever the situation needs.
Too often its not feasible to try to make the plan conform to the block or your using a plan that wasn't drawn for ICF originally. I draw most of my plans and started out making everything work with the block in my opinion its not worth it.

Not to derail this but, Eric the scaffold thats hanging on the ext of your walls without any diagonals, how are those attached to the wall?

Jim :
The bracket has 16 ins of 3/4 fast thread rod that goes thru a 1in conduit sleeve poured into the wall.
Plywood washer and nut on inside of the wall.


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Eric,
Is that its only purpose?

Jim : Do you mean the brackets only purpose ?

Yes, essentially.

Excellent for staging re shingles, roof sheeting, soffit.

We stick'em thru wood frame walls too.