I am planning (a while from now) a home build using Fox Blocks.  They are the only locally sold product here and they seem to be reputable.

I want to do 8" core basement walls and then 6" core main floor walls.  I have had a 9' basement foundation wall currently and I would really like something like a full 8' basement wall instead.  9' is too much, more excessive to me and also it's not achievable with an even number of blocks (16" tall) where as 8' tall would be 6 blocks.  However, I don't want the basement floor to subtract from the basement wall height...so I am wondering how to get an 8' basement wall and then be able to install 6" core blocks ontop of the basement wall.  If I cut the top row of basement blocks, that would mean no edge to lock in.  Can this be done? Can you not change core thickness from one floor to another?

EDIT: I also don't know how I could do 8' walls with floor joists hanging on the basement foundation walls.  This would subtract nearly 1' of headroom.  So far, it's looking like joists will have to be raised up with some method, either 1 more row of blocks or with hanger on the 6" core walls.

I would suggest contacting your Fox Dealer with this type of question. They should be able to offer suggestions.

Depending how you are connecting your floor, you may be able to simply attach your floor system higher up in the 6" block (poured at same time as basement forms). Whether or not this is doable depends on your floor connection detail (eg, brick ledge for floor support limits adjustability; anchor bolts, ICFVL, ICF-Connect, etc. allow for adjustment within a course of block).

Speaking with your dealer may give you a better answer, as he is familiar with your project, local code, available products, etc.

I use Fox block for over 50% of my installs. When transitioning from the 8" to the 6" the 6" block will rest on the inside lip of 8". I usually pour the 8" foundation walls first for joist bearing and then work off the deck to install first floor walls. To start the 6" on top of the 8" you'll need to cut the tabs off the inside bottom of the 6" block and foam glue in place. I recommend an 8'8" basement which can be achieved by either ripping a full block to two 8" tall pieces, less expensive than buying the 1/2 tall forms. This will allow for 2" of Dow board on top of the footing with a 4" basement slab. You will still have a 8'2" basement height.

ICFBdr is correct to point out that using a 6" on top of your 8" will require a floor hanging system. Check out Watkins hangers for another option. I believe this system is more simple.

Couldn't you use a taper top block on the top of the basement wall to set your floor joists or trusses on and eliminate the hanger hassle? Hangers are a large cost.

http://www.foxblocks.com/products/fox-blocks/taper-block/

I have made contact with the dealer to get more location related information. I did some digging and it looks like I can buy 4" height addition pieces. I was thinking one row would be perfect but then I started wondering about my floor system and how it may tie in. I am thinking I may have to go 9' tall and then hang my 11-7/8" I Joists from the top, meaning I lose nearly 1' after the joist sinks into the hanger. I'm not finding much info in terms of how the joist hangs or sits on the basement wall and how to reduce down to 6" after the floor is in place. Anyone have some on-site pictures or detailed drawings? I think I am in the right place though to seek this info, seems to be some ICF pros here...and in my local area they are zilch/non-existent.

So to transition from 8, to 6" I have to cut the tabs off of the inside of the 6" base block and use the spray foam to essentially glue the block to the surface of the basement foundation wall, which, I originally planned on being a very rough top for good bond but now sounds like I need to rough up only some of it that will tie in with the 6" blocks and have a very smooth surface for the inside layer of the 6" block to rest and get glued on. Yikes!

The 8'8 sounds great. How do you make up for the flat edges of the fox blocks since the bottom half's top will be smooth and the top half's bottom will be smooth from that cut? No more interlocking edges when I rip the block, right?

I will definitely have to hang my joists somehow. I was going to use anchor bolts installed and held in place with plywood scraps, and then anchor either a.) joist hangers to the bolts or b.) a ledger board that I could then install i-jost hangers on. I will google the watkins hangers.

Sorry, newbostoncost, I was typing out as you made the post.

I think that is one option I would consider but it heavily depends on my final row of blocks. If I am ripping straight blocks in half to get the 8'8" then I can't efficiently use the taper top. I also do not know how my building department would feel with just the 2" edge for the joists hanging. I could cut the 6" block bottom out for each joist but that's all more potential for blowout at a high pressure point (very bottom of the 2nd pour) I definitely will throw the idea in my options. I want to see how some pros do it and learn from their experience.

If you put a wood sill plate on top of the taper icf block code says you only need an inch and half of bearing. Look at code R502.6

http://codes.iccsafe.org/app/book/content/2015-I-Codes/2015%20IRC%20HTML/Chapter%205.html

Unless you need the 8" form for strength, there really is no reason to do it. I sell and tech Fox exclusively and I also tell my customers to think everything thru prior to deciding on an 8' basement. With 7 courses of Fox you get 9' 4" from the footing, by the time you get the floor in and a beam and ductwork plus plumbing, you are hard pressed to get an 8' finished height. I would opt for a 6" Fox block all the way up. Take the $$ you save in concrete and put it towards the 7th course of block. Use the Simpson or Watkins hangers and you will be fine. I like to pour the basement 10-12" above sub floor. It saves the block edges and gets a lot of concrete around the hangers. Good Luck. If I can help in any way let me know.
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newbostonconst - are you saying to rest the 2x in the vertical position and then install hangers on that, to set in the joists? I'm not sure how you mean to 'put a wood sill plate on top of the taper' it looks like I'd have 2" of concrete that tapers into the main wall to maybe rest the 2x sill plate on, but I don't see the benefit. I joists need 3" of bearing if it's on masonry, or 1.5" if it's on metal or wood...in this case I would feel more comfortable with hangers rather than joists riding on 1.5" of a sill plate in vertical position. Maybe I'm not following.

emmet - I like the traditional strength added from a 8" thick core, especially if I am to be doing 6" above. I know I can use extra rebar in a 6" wall, but all walls are 8" thick around here. It's heavy clay backfill and this will be backfilled on all 4 sides. I'm okay with the idea of 7 rows instead of 6 after I realized hanging the joists is different than setting them ontop of the basement foundation like standard framing. Can you explain what you mean by pouring the basement 10-12" above sub floor?

If you are going 8" on the bottom. Stack 7 courses of 8" fox Blocks then stack 2 courses of 6" Fox Blocks on top of that. Install which ever hanger you are going to use in the lower 6" block and pour half way up the upper 6" block. Depending on your site conditions, I would opt to brace on the outside, because of the different thicknesses. I also tell my customers, and this is just food for thought, backfilling with good clean sand is cheap in the long run. I don't know what it will cost you to import to your site but it is $$ well spent.

emmet - That would suggest I would be hanging the joists from the 6" core blocks where if I went 7 courses, I would hang from the 8" core, flush with the top of that row...meaning the floor joist "sinks" into the hangers that are mounted on the 7th course. Right?

So it sounds like you are suggesting I pour the 8" core basement wall + 2 rows of 6" core blocks that are braced, all at once instead of 8" core first pour, then 6" core second pour. I can see that working out, since i would be securing the start of my 6" blocks to the basement wall, though I need something to secure the inside-side of my 6" blocks since they would be floating on thin air, since they won't match the 8" core block inside top edge.

No. Stack the 7 - 8" courses, then stack the 2-6" courses. Install your hangers in the bottom 6" course, the joist will "sit" on top of the 7th course. Pour all of these blocks at one time, stopping half wY up the 2nd 6" course. Brace from the outside. This allows you to clip the next starting course of 6" Fox blocks to a course already poured. It also lets you do a good neat job on all your door openings. You are pouring @ 11'4" with the first pour.

You need not worry about the inside of the 6" block. The bracing holds it in place.

Wow! 11' 4" on the first pour, for a first timer is rather intimidating. Could I pour half of the basement blocks, and essentially break this into 3 pours so that my first pour is easy practice and secures everything? This gives more strength for the middle pour which would be like 5' of 8" core, then the 2' of 6" core blocks.

I'm having a hard time picturing bracing done on this especially at the intersection between 8" and 6" blocks.
1.) That means I will have an 8'8" or 8'6" basement floor to ceiling depth.
2.) The Floors joists would only visually be resting on the 2" thick foam that juts out from the 8" core blocks, but they are fastened to the 6" block with hangers. Correct?

Pictures of this being done on a site would be helpful if anyone has some!

CTSNicholas- As you are reading, there are many ways to accomplish what you desire. For myself, I start with the cut 1/2 block on the bottom of the 8" wall glued to the footing, cut side down (this prevents blowout from weakness). Stack the remaining 6 courses with a taper top at TOW or you can simply use a saw zall to cut in a taper top, again, less expensive. A 6"foundation wall may suffice, as has been recommended, but I would first check with local codes as this does not achieve "prescriptive build" in our locale and therefore would require an engineering stamp of approval.

You will need to check with your code also if you attempt to use the 1 1/2" of tapered concrete for bearing. This would also be frowned upon in my locale. If you were to attempt savings by using less concrete Fox Block manufactures a 4" to use on your first floor, allowing a much easier deck installation. This also avails extra living space on the first floor. It still achieves the incredible insulation value of an ICF but may not withstand an attack from the US military. When pouring the basement walls be sure your re-rod extends at least 2 feet above TOW and there will be no worries as to the strength of your cold joint.

Should you feel the need for 6" first floor walls, I would use a brick ledge, Watkins hanger, the 2 piece Simpson ICF ledger system, or a manufacturer's recommendation.

You are right about the 11'4" pour. We installers would consider this easy, but that is because we usually have an experiences crew of 3-4 guys for problems like block lifting and separating from vibrating, wall straightening, anchor adjusting, beam pockets, and other such installation mishaps. DIYs need plenty of help on pour day with a block rep on hand if possible. Pour day will go much easier if you over brace and aren't afraid to use foam glue. You have a lot of good advice here on this forum and you are asking the right questions. I am sure your project will be successful.

You are right about the joists The 11' 4" isn't too bad. Install the block per the instructions. You can also email me. [email protected]

Where are you located?

Joe, what is TOW? I do realize there are many ways to do what I am trying to do. I believe cutting the block in half as you say is most practical.

I do not believe the 1 1/2" of tapered concrete will work for bearing here. I have not considered the 4" block for the main floor. I could not convince the local assessors to not tax me for outside sq ft since my walls may near 1' thick. They argued all brick homes are assessed by outside sq ft. So the 4" would save some precious space, however I am thinking 6" for tornado season and for the sound dampening. Not sure how strong the 4" would be in terms of flying debris and probably less sound proof...? I found the Watkins hangers. WOW, they are not cheap. $810 for 60 of them! I'd be better off using J bolts horizontally to hang a ledger board and then using the $2 joist hangers... I am not sure what the 2 piece Simpson tie is. Got a link?

I don't feel comfortable doing an 11' 4" pour, there are not really any ICF installers I know of here, so I am looking outside of my locale to see if I can find any. Not too sure how they'd feel about me doing all the work up to the pour point. I like the idea of the 8" and 6" block being bound together in one pour, but if I do that, I'd definitely be doing half the basement wall, then a 2nd pour, and then a 3rd final pour for the final height.

I am located in S.W. Nebraska.

I wound up with an even 8' basement wall with my fox block stack... 6 courses of 8" block, 1 course of corbel ledge, ledge facing inward, and first course of 6" block on top of the corbel. 1 1/2" sill cut to fit the corbel ledge(about 6 1/2" of bearing surface at the corbel after the transition to the 6" block. Resting on the sill I used 14" tall top chord hung 4X2 trusses with a doubled top chord where it bears on the sill.. That tall a truss worked well for the desired load and span for our main floor. This leaves just a hair over 8'-4" of distance between the truss bottom and the top of the footing. Add a 4" basement slab poured over the top of the footing neat against the base of the ICF(provides basement wall restraint) and there is your 8' basement wall...