Bear with me, I've not worked with ICFs before.

Today, I went to the lumberyard and played around with a couple of Logix blocks.  I'm trying to get it straight in my head about cutting blocks shorter as the makeup pieces of walls that aren't modular in length.

Whacking a block is easy if your cut clears a web.  One cut through each sidewall and you're done.  It is when your cut looks as if it will go through a web, that you need to revert to plan B.

Plan B begins with understanding the modular distance of the interlock bosses that are molded into the top and bottom edges of common blocks.  Depending on the block design, manufacturer to manufacturer, this "pitch" of the interlock bosses might vary from 3/4" to 1-1/2" or even 2".

You can readily find the pitch by taking two blocks, mating one to the other directly atop, then taking them apart and seeing what minimum distance they can be offset and then mate again.  The offset is the pitch of the interlocks.

Use the offset difference, the interlock pitch, and measure one, or two, or three offsets off the starting end of the block, then remeasure for your filler block length from your mark, and see if you now clear the web in question.  You'll need a "starter side" cut and a "finish to length" cut, both cuts clearing webs.  When things look right, you'll make four cuts, two through each sideboard of the block.

You'll end up with a block that is the right length, and will at least interlock with ONE of the two blocks it will sit atop of.  You'll have to knife out or saw out interlocks that don't mate, and want to interfere instead.

You pros that have done this already, please stop snoring.  I'm just writing this as therapy to help me think it through, and to perhaps assist other newbies.

Don't forget while doing this you must also keep the webs aligned in a vertical line from floor to ceiling or else the drywaller will hunt you down.

And also make sure you don't exceed the manufacturers recommended web to web distance.

Gene,

It sounds like you are taking the extremely difficult route to ICF construction. It sounds like you could use a good basic class to help you along. I have built the majority of my buildings with Logix so I am familiar with the product.

There are two basic principles that govern how to build with ICF. 1. If your building is designed to the specific product you are using then cuts should happen on the interlock lines. (Side note, to begin with always cut on the line it will make your life easier.) This allows you to start in one corner and go around the building cutting on the lines. 2. If it is very critical where your corners land and or the building was not designed to the specific product you are using then start at each corner and build to the center of your wall some where. We like to have the seam fall on a door perferable or a window. Sometimes this doesn't happen and you end up with a seam in the middle of the wall. These seams are easy to take care of, just use your spray foam and close the gap. We always cleat across these types of joints although if the seam is farther then 4 feet from a corner some people don't cleat these joints.

If it was me, I would get into a good installers class.

ICF Contractor

Most blocks have either a 1" or 2" cut line embossed into the foam.  When you learn the system you don't need a tape on the job.  If the job is big enough you can set up a "cut man" to feed two or more block layers.  They can call for a block by giving the no. of cut lines before the first tie, the no. of ties and the no. of cut lines after the last tie.   that should really confuse you, but I hope not.  IE a 3-4-2

There are also blocks out there that do not have an interlock but use glue for this purpose, either way the point made above is that the tie should always line up and if the tie lines up so should the interlock. When you need to do the splice that you have mentioned, it is stated often in this web site splice at openings to help reduce the number of splices. When you have no openings then put all of your splices in the middle of the wall and scab both sides to reinforce the seam that you have created, this method will also keep the rock hanger off your case.

Gene, if I understood you correctly it sounds like your explanation is cutting one block on each end to make it fit the opening without cutting on the tie, if that was the case your ties will miss align for too much area. You want to cut 2" inches off the block your measuring too, which adds 2" too the block your measuring and gets you off the tie. Allot of the questions your asking are basic and should be answered by your local distributor of the block your using. It sounds like maybe you were sold on a lesser expensive block that has no local support?

Dave