If using ICF for main build why would you use block for basement
some icf systems will suggest thickerwall section for basement -
decide on system then look at their detail for basement build,
will all depend on your ground type and water table height
thats job for your engineer?arcitect ?

If using ICF for main build why would you use block for basement
some icf systems will suggest thickerwall section for basement -
decide on system then look at their detail for basement build,
will all depend on your ground type and water table height
thats job for your engineer?arcitect ?

Polycrete makes an ICF footing form that can be up to 36" wide. Typical is 12" x 24". You set the footing forms in place, put a course or 2 of ICF on top and pour it all at once. PM me for more details or check out polycreteusa (dot) com

I would recommend pouring a standard footing first using dimensional lumber (take time to make sure it is level and it will make the next steps easier!). Building the footing separately allows you to chalk your foundation on the cured footing to ensure the basement is starting perfectly square (especially true if you have a more complex AKA more than 4 corners design) and allows for forms to be re-leveled after a couple courses of forms are placed. It is an extra step, but there are fewer moving parts on pour day so quality control can be monitored more closely (it sounds like this is a DIY project, and possibly your first attempt at ICF, so I would strongly encourage the KISS principle).

Also - pouring the footing monolithically with a row or 2 of forms would result in a cold joint 3-4 feet above the footing. In my experience, engineers are not fond of cold joints in foundation walls, so I would discourage this approach for a full height basement.

I used Fastfoot for my ICF basement footings and have photos on the Fastfoot website - see below. It worked great and was easy to install and get level. I have 2 levels of ICF -basement (10' x 8" core) + main floor (9' x 6" core), and built on hard red clay. I went with 12" deep x 30" wide footings. Probably overkill, but I also have 8" concrete blocks up to grade level outside my ICF basement wall for a brick ledge, so the wider footing just worked out better.

After the footings were placed and plumbing and gravel set in place, I attached a form edge board to the top of my footings and poured my basement slab before I stacked my ICF walls. This gave me a nice surface to work on and also made finishing the basement slab easy as the finishers had access all around the slab. It also provided a solid backing to support the bottom inside edge of the ICF forms during the pour. I moved the form edge boards used to form the slab edge to outside the ICF blocks to hold them in place during the pour.

KISS principle?

Keep It Simple Stupid.....

As long as you have rebar extending up out of pour 1, there is no issue with a cold joint.

Scottishjohn- by standard footer I meant the poured footer, so no block in the foundation.

ICFBdr- I would set the fast footer up to be able to pour the whole basement wall up to just about the floor joists to avoid that cold joint, unless there is an issue with doing that?

Posted By redmst1969 on 07 Dec 2018 03:35 PM

ICFBdr- I would set the fast footer up to be able to pour the whole basement wall up to just about the floor joists to avoid that cold joint, unless there is an issue with doing that?

How do you support and brace the ICF during assembly and pour doing it that way?

Arkie6

They make those adjustable footings you put on the ICF when you are doing the Fastfoot method. They allow you to quickly adjust the height of the blocks on each side, allowing you to level the block. As far as bracing the rest of the wall, it would be the same as building the wall on a Traditional foundation/footing

My biggest concern doing it that way is keep the basement square on the adjustable footpads (again - more of an issue with a complex basement vs. one with just 4 corners). It is easier to simply chalk a line on a pre-poured footing and set forms on this line - also allows for shimming/re-leveling after a couple courses of block.

Bruce - Even with the rebar extending through the 2 pours, a cold joint is still present. This weak spot can be remedied with extra rebar, but this does not eliminate the joint cold. In my experience on commercial and residential projects, engineers are not fond of cold joints in foundation walls. These are best place a the level of the floor system (when possible), since the floor will provide lateral support at the cold joint (ie, weak spot). Cold joint at connection between footing/wall is not a concern, since the basement slab will be poured there and dowels and/or keyway will provide added lateral support.

Right, engineers and knowledgeable inspectors don’t allow concrete wall cold joints without additional structural strength mitigation.

Been doing mono pours for 14 years. Simple once you get your system set up. We added a step 3 years ago. Footing, walls and floor poured in one shot. Slick.

Posted By smartwall on 08 Dec 2018 12:13 AM
Been doing mono pours for 14 years. Simple once you get your system set up. We added a step 3 years ago. Footing, walls and floor poured in one shot. Slick.

How do you do the floor at the same time?

I'm not sure if this is a trick question. We pour the footing first, then the walls , with the floor being last.

Posted By smartwall on 08 Dec 2018 01:42 PM
I'm not sure if this is a trick question. We pour the footing first, then the walls , with the floor being last.

If the supports are in the inside of the building, how do you pour the slab at the same time? Supports on the outside or block out where the supports rest on the ground?

Supports are on the outside. Started using Zonts and Zuckles versus my old stongbacks. The adjustable arms on the standard bracing wouldn't work because the arms often had to be almost parallel with the ground. The Zuckles do the job.

Posted By smartwall on 09 Dec 2018 12:20 AM
Supports are on the outside. Started using Zonts and Zuckles versus my old stongbacks. The adjustable arms on the standard bracing wouldn't work because the arms often had to be almost parallel with the ground. The Zuckles do the job.

I was wondering about that, everything I have read recommends putting the supports on the inside of the wall.  How well do they work on the outside vs the inside of the wall?  How much more do you have to excavate to be able to put the supports on the outside of the wall?