Guys, I have been pondering a couple of details regarding my ICF-build. We're planning to start stacking blocks next week. I've hired an "experienced" installer, but question some of his responses on these items. FYI, I'm using Nudura.

1. Do you trim the interlocking protrusions of the bottom of the first course and top of the last course? I specified 9 ft. ceilings in some portions of the house and it would seem necessary to trim the "nubs" to achieve a 9 ft. wall (6 courses) based on the Nudura block dwgs. I'm sure the interior framing could accomodate a off-nominal height, but it would be easier to use pre-cut studs.

2. My foundation is slab on grade with 2 in. of exterior footing insulation. For the first course of block, can the block exterior surface sit flush with the exterior footing insulation. The 6" concrete core will sit about 5/8" onto the footing (or depending how you look at it) the outer ICF foam will only sit 5/8" onto the foundation. Does this interface at the foundation need any additional strapping to prevent lateral loss of integrity? I plan to use low expansion foam to seal/adhere the block to the foam/slab at this interface.

3. Are there any limitations on using scrap pieces (too short, etc.)? For example, for a 3050 window, I'll likely have a bunch of 3' long pieces with the webs spaced different lengths from the cut. Obviously these types of remanants could be used where a partial block is needed at the middle of a wall. Can a number of them be used say on a final course where hydrostatic pressure is less, with additional strapping, etc.?

4. I have some 13'6" walls and am using Nudura bracing that I believe only goes to 10'. Any suggestions on how to accomodate this taller wall aside from finding some taller bracing? Perhaps, putting a horizontal piece of 2x across multiple webs on the 2nd course as the "base" for the box channel?

Thanks in advance for any of your insights!

I would double check with your NUDURA supplier if you have any questions.

No problem leaving the buttons on at the bottom of the block.

Not 100% sure what you mean with your footing question, just be sure you have enough bearing for your soil conditions to satisfy local codes.

Virtually any cut piece of form can be used. Simply cut the block to make a factory end (ie, 4" foam from web or on the second cut line) to ensure all webs line up. It is best to use these pieces on the second row from the top. This minimizes pressure, while keeping longer pieces to lock in the final row.

NUDURA does have 12' Channels available with their bracing if the 10' is not enough.

Good luck!

Thanks, ICFBdr.

Sorry it took so long for me to reply. We ended up leaving the buttons on the top and bottom of the first and last courses of block, respectively. I kind-of wish we had cut them off. The height of 6-courses is 9'1" plus the top plate totalling approximately 110.5". A interior partition wall with 9 ft precut studs, and double-top plate is 109.125". So, it would seem we have to either use 10 ft. studs and cut them down, or run a triple-top plate slightly shaved down (or shim the last 1+ inches). Seems like it would have been easier to have the 3/8" inch gap with the buttons cut-off and use OSB to shim above the top plate.

So far, we've had very little scrap. Quite amazing.

We're using a bracing system that I believe was from ARXX. It has metal scaffolding (rather than having to use lumber) and 12 ft. tall channels, with 4 ft. extension pieces for the tall walls. Seems to work quite well.

We should be pouring the walls end of this week or beginning of next. Wish me luck!

Posted By snoslidr74 on 28 Jan 2013 02:14 PM


We should be pouring the walls end of this week or beginning of next. Wish me luck!

Where are you located at that you can be pouring in January?

It's unfortunate that ICF doesn't match heights of precut studs or various floor systems to eliminate this, the manufacturers would have to have molds at the factory coming out of the ying yang to appease everyone. Cutting is something of a standard for us installers. You cannot dictate top or bottom to cut, every job is different, so proper layout and though process helps determine what/where is the best place to cut...and installer preference. Personally I prefer top cuts whenever possible.

It was -16 last Thursday, -22 with the windchill...we poured

Posted By Chris Johnson on 29 Jan 2013 08:22 AM
. . .
It was -16 last Thursday, -22 with the windchill...we poured

I assume this was in ICF forms.  Did you use an accelerator in the mix.  I guess you did insulate the top of the wall after concrete was placed?  No freezing problems with the concrete?

I'm in southern New Mexico. Supposed to be lows around 40F with highs near 70F at the end of the week. From what I understand, that should be sufficient to not need any accelerator.

Alton, it was the footing, walls are next week.

We cover with insulated tarps, there is some accelerator in the mix, it's a weather mix design from LaFarge. Knock on wood, have not had any problems with winter pours.

The rumour is the coldest pour was -57 in northern Canada and they poured, I wasn't there, just heard the story from over 10 years ago, to this day I question the validity of it as I can't see any pump operator jeopardizing his hydraulics in that temp, but who knows.

I did pour once at a temp of -23 with windchill at least -27 and the pump operator was over an hour on set up because of the cold and I thought at one point he was going to fold it up and go home. In the winter is the only time we pray the concrete shows up at over 90F.