As I am firming up my design, we will have a walk out basement. The plan is to use an ICF basement, with 12" double stud walls for the upper part of the house. My original thought was to do the ICF on the 3 "below grade" sides, and then change to the double stud wall on the walk out side to save cost and make for easier construction of windows, doors, etc. (plus if a RO gets framed wrong or something changes, we are fixing wood and not concrete...). Besides that, the other reason is it is a long (60') exposted wall on the north face. I was thinking the r-40+ double stud would be a much better option then the r-25ish ICF wall. Are there any thoughts on this? Would it still make a better/stronger basement 'system' if all the walls were ICF? I realize the length is quite long, which is why I am curious if it would even help make any difference or not.

Why not just go to quadlock.com and find the ICF wall with the R-value that you want. They go up to R-80 or more...

forget wood. It rots.

nuff said.

Work out your costs on the double stud wall compared to the ICF wall, I think you will be shocked to say the least.

The R-25 you quoted for ICF is not a real number, it is real, but it's not realistic, since ICF when filled with concrete have literally zero air infiltration, look at it from a K value and you will be shocked again. R value is based on the product value but not the system value and you can create a better system far more cost effectively with ICF then framed and stuffed walls.

Would it still make a better/stronger basement 'system' if all the walls were ICF?

Yes. Complete the square with ICF at the very least.
I'm also a big proponent of making some interior basement walls ICF as well, particularly on long runs as you describe.

speaking of cost do any of you have an idea of what it should cost me to do a 3000 sq ft. home, plus a full basement. I was talking to a passive house guy and he was throwing numbers at me that I was not expecting. I am trying to decide if I am going to go traditional with spray in cellulose or do a ICF home. It will come down to cost but it is so hard to get cost numbers on generic sq ft. The passive house guy said to build passive I am looking at $175 a sq ft with reasonable upgrades and to do an ICF basement my add another 100k to the project. Interested to hear what you guys have to say.

ll1542: Depends on your location. A typical ICF basement installed by an experienced professional should cost you about $12 per square foot of wall, give or take a buck. Others here may disagree, but you get what you pay for. Not sure how that will add up to an additional $100k, but is that compared to no basement at all? $100k should buy you a basement 231' x 231' nine feet tall. Big house.

My all-ICF home was around $150 per sq ft with an unfinished full basement. It's about 2800 sq ft. I'm located in Illinois. This was in line with what we expected to pay and was comparable to our estimates with 2x6 framing and closed cell foam.

galnar, I would like to hear more about your project. Is that price including the property? What kind of heating and cooling did you put in? what kind of ceiling? and was it builder grade inside or better? Thanks for any more info you are willing to share.Thanks

you guys are comparing floor sqft price of a complete home vs wall ICF sqft price which only includes labor rebar concrete and ICF...

tsk tsk tsk

Baldwin, He's asking two different questions. The first is how much for a basement and the other is how much for an entire house. His builder does not seem to want to do an ICF basement so he told him it'll cost an extra hundred grand. That's a hell of a big basement @ $12 per wsf.

Sorry, double post.

speaking of cost do any of you have an idea of what it should cost me to do a 3000 sq ft. home, plus a full basement

Is 3000 sf the total footprint of a single floor like a ranch style or are you talking about a two story building with 1500 up and 1500 down plus a similar basement for a total of 4500 sf?

We are doing a two story colonial, more down than up I dont have a real accurate breakdown. But master on the main and three rooms up for the kids. so that is 3000 total then we also want a full unfinished basement. Hope this sheds a little light on what we are trying to do. I would like to do ICF all the way but everyone I speak to says "oh way to expensive" you can get the same results if you build right blah blah. Problem is trying to find anyone who wants to build beyond a 2x4 construction. So I found this guy who is doing passive home but I am just thinking that for the same money I probably could do ICF and a high R roof also. So any info on what I am into would really help me focus my efforts. Thanks

"oh way to expensive"

Translation: "I'm not very experienced with ICF and I'd have to charge you too much. Let's stick to something I can do" You really have to find a contractor who has a good track record with ICF. All the other ones will try to sell you something else or charge you too much for their learning curve. You can contact the various block distributors and ask them for contacts to contractors who do a lot of ICF. Or you can contact an architect who has done some and ask which builders have executed well.

If you assume your colonial is a square box, 40' on a side, and that you are going to do all three levels with ICF, then you have 160 linear feet with an overall height of about 27 feet. That is a total of 4320 square feet of wall which is one of the ways you can estimate cost. Wall runs from $13 to $20 a square foot depending on some variables, which gives you a range of $56,000 - $86,000 for the ICF portion. Of course, floors and roofs aren't included, and neither are footings, but it is a start.

I just did an ICF with 1300 sf (of floor space, not wall) in the basement and 3800 sf on the main floor for about $110K. That included all the ICF and all the floor slabs and all the footings and the Insuldeck ceiling above the basement. It was about 5600 sf of "wall" for comparison.

Building with ICF does cost more, but it is not the same result as stick building, either.

Where are you located? I hope this helps your planning.

I am located in south new jersey not far from philadelphia. So for the main floor you did a concrete floor? I have heard of this what are the advantages to doing a floor this way over a normal engineered joist floor? Also, if you do a concrete floor can you install all the traditional type floor coverings such as hardwoods? Thanks for all the info, it is very appreciated.

ll1542: I sent you a message offline.

I have heard of this what are the advantages to doing a floor this way over a normal engineered joist floor?

Yep, concrete over basement using a product called Insuldeck and concrete slab inside of the ICF walls for the rest.

1. No bouncing and solid feel underfoot.
2. Fireproof.
3. Allows basement rooms to have concrete over for security.
4. Strengthens entire build and adds earthquake resistance.
5. Allows energy-efficient radiant floors over basement.
6. Allows thermal mass for passive solar areas.
7. Soundproofs living areas from basement noise.
8. It was quick.


You can use all the regular floor coverings; you just need to pay attention to how they are done. The downside is HARD floors. If you want to put a dance-able floor in, for example, you would want to do something to soften it up, like padding or spring it some.

I was wondering about how hard this kind of floor would be underfoot. I used to work in a warehouse and always thought the concrete floors were rough on me. It sounds like a great idea other than that. And is there anyway around that like a rubber underlayment or something like that. We want hardwoods on the main floor and carpet in the bedrooms.

There is a dealer for Lite Deck in Malverne, PA. Rich Jones of Foam Form Technologies Call him and talk to him. He's a great guy.

And is there anyway around that like a rubber underlayment or something like that. We want hardwoods on the main floor and carpet in the bedrooms.

Yes, any amount of rubber underlayment can alleviate the hardness, but keep in mind that any insulative material you use above the radiant surface (like carpet and carpet pads) can reduce the efficiency of the radiant heating. You would want to make sure the slab was adequately insulated underneath.