One of the only contractors in my area, (north central Kansas) that does ICF's does NOT recommend them--told me there was no benefit to the insulation because of mild ground temps and that it's hard to waterproof. He is recommending we use custome made aluminum forms (8'4'). I was under the impression that ICF's are more stable and improve on wall strength. Can anyone shed some light on this?

He's likely not familiar with IFC's and wants to use old school he's used to.

Is he going to insulate his poured walls or not, ask him about wing foundation insulation he'll tell you you don't need that I guess too.

Years ago I had a home built (before I knew better) with poured formed basements walls, no way would I not want an IFC build over that.

There is a benefit if your ground temp is maintained around the basement walls & under the slab with the IFC insulation and wing insulation minimizing the heat loss.

For example I'm building where ground temp is 62, a slab not a basement but same issues.
I'm using 3lb density insulation under the footing and wing insulation 2" 4' all round the perimeter.

Look this up online they have a lot of info.

Remember a contractor is like your employee, he has to do what you want, not what he wants, he can give you his opinion and ideas but research them and make your own decision.

You don't say so, but it sounds like he doesn't recommend ICF for the basement. You say he does ICF, but doesn't recommend it? I don't see why ICF is hard to waterproof- no harder than poured concrete. Concrete cracks- it just does, so you have to waterproof properly in either case. I don't think ICF is stronger or more stable than a poured wall, though. The foam doesn't add a whole lot of structural strength.

Our basement (and the upper walls) of our house in SC are ICF, and I love the performance. I don't know what our ground temp is, but it's probably higher than Kansas. Plus- part of a basement is above ground and not protected by ground temperature. Our basement stays at 60 or above in the winter, and no higher than 78 in the summer with no HVAC. We've never had a drop of water in the basement. Waterproofing consists of a Grace peel and stick, covered by dimple board, with gravel backfill and a perimeter drain at the bottom. I believe you need all of that by code in most places. I also graded the topsoil to drain away from the house, and installed gutters to prevent all that water from dumping next to the foundation.

You're contractor is an idiot. You can tell I said so. I saw that the temp in Kansas was 105 yesterday, That means the temp at the top of an uninsulated foundation is what, maybe 104. What are the temps. on the top of that foundation in let's say January 30 in Kansas?

Yeah i would seriously doubt any contractor who has any experience with ICF saying they are not worth it, plus on another note- don't you guys have a lot of tornadoes too? just saying?

Thanks for all the input!!

My concern is the same as some of your suspicions--he's not terribly familiar with ICF's. I think I will keep looking to find someone who has more experience. I should mention that this is a basement for a house that we are moving to a new location. It's 120 years old, and oddly shaped (Victorian).

So, if a traditional foundation will last as long and be just as stable--what are the benefits of ICF? And which blocks seem better? This contractor was using lite form.

Thank you for all the advice!!

JDebree. Sorry. Yes, it's for a basement. He does more above ground walls. He lacked confidence in ICF basement construction, particularly due to what he said was difficulty in waterproofing.

I think if he sees a regular block he may be more confident. Basic principles of building apply to icfs .

Is liteform an inferior block?

So, I had theorized that the insulated forms slowed the cure and perhaps increased psi--you're saying this hasn't been the case in your experience? Also, what does "gravel" look like in SC? When I request gravel backfill, I wanna make sure I'm asking for the right thing as this can mean different things in different areas.

I suppose the concrete in an ICF wall is stronger than conventional concrete, but my house is engineered to standard concrete specs. If it is a bit stronger, that's a bonus. We used a sharp crushed gravel (3/4" IIRC) to backfill around the foundation, then covered it in geotextile cloth and a layer of dirt. The fabric keeps the gravel from filling in with dirt over the years. Sharp gravel locks together and becomes quite stable, while round gravel like river rock tends to remain unstable (think ball bearings). It's important to use a dimple board to protect the sealer used from the gravel. We have clay soil with poor to fair drainage, so we wanted to be sure moisture wouldn't get stuck against the foundation for long periods. Having grown up in old house with wet basements, I obsessed a bit over having a dry basement, plus I wanted that space to be fully usable.

Posted By JRTebow on 23 Jul 2015 05:26 PM
Is liteform an inferior block?

LiteForm is what I used on my ICF home, from footings to roof trusses, which includes a basement and single story.  I had no issues with it, but I used the LiteForm Xtra forms that are 2.5" thick and have a smooth outside face (the ties are in slots 1/2" behind the face of the foam.  But I don't think the Xtra forms are available any longer.  Normal LiteForm is 2" thick with the ties exposed on the face of the foam.  This creates a somewhat irregular bumpy surface that may be somewhat harder to get peel-and-stick waterproofing membrane to adhere to.  I'm not sure, just speculating here.  I had no issues applying the waterproofing membrane to the LiteForm Xtra.  I would recommend the use of the ICF foam primer prior to applying any peel-and-stick to get better adhesion.

JRTebow, I agree with your theory on the cure yielding increased psi but generally this cure strength is exaggerated by folks. It's not that its slower necessarily but it changes the curve. Because if this cure ICF appears to cure slightly more after 30-90 days than it might otherwise. ICF is technically a moist cure which means it will be stronger than a cure that is otherwise influenced by more evaporative cooling, solar radiation, etc. You will find engineers out there that disagree though but some of these are using cores that are too small in diameter to meet ACI minimum. Also, I agree with smartwall and Bill about this contractor --- he may just be saying he's an ICF guy. More common: builders say they've done ICF and don't like it when in fact they just don't want to build better -- just want to build the same way as granddad. Regards.

Posted By JRTebow on 23 Jul 2015 05:32 PM
... Also, what does "gravel" look like in SC? When I request gravel backfill, I wanna make sure I'm asking for the right thing as this can mean different things in different areas.

I'm in Arkansas on the Arkansas River.  We have sand & gravel mines nearby as well as a rock quarry.  When I specify "gravel", I get smooth round stones mined from the pits adjacent to the Arkansas River.  There are different sizes available such as pea gravel and 1-1/4".  1-1/4" gravel is what I used around my 4" perforated pipe adjacent to my footings to create a french drain.  I like this rock in this application because it has large voids between the stones and the stone was essentially captured by the the footing on one side and the earth on the other side.  Under my basement slab I used clean 3/4" "crushed stone" from the rock quarry because it locks together better than the round stones, but it also costs a lot more.  For backfill against my basement walls, I used "fill sand" because of its low cost and good drainage characteristics.  I also built on top of a red clay hill and there is little if any ground water to deal with.  The fill sand consists of everything from coarse sand to small gravel extracted straight from the mine.  The french drain rock was covered with filter fabric prior to back filling with the sand to keep the voids in the rock open.  I used red clay backfill for the last foot or so to create a cap to block surface water from migrating down to the fill sand, and then put ~6" of topsoil on top of that.  Rather than dimple board over my water proofing membrane, I used Polyguard LowFlow protection and drainage mat.  It was easy to work with and costs much less than dimple board.

I would call the local sand/gravel/crushed stone supplier and see what they have available and tell them your application and see what they suggest.

Lite form is not an inferior form per se but since your contractor is a bit skittish a standard block would be preferable since it is already built and not a knock down. With the planks 8" high versus a standard 16" high block, more seams means less stability.

Great information on gravel and materials for waterproofing. We may DIY some of this to cut our costs--not the concrete and framing--my husband only worked with a concrete contractor for a year, so doesn't feel he has the sufficient expertise. However, he is a seasoned house builder and finish carpenter, and feels he could manage the waterproofing aspect on his own--save us some money. Any cautionary thoughts on this?

You will have a lot less water problems if you don't build anything underground. Frost protected shallow foundations make that a cost effective way to go.

With deep subsoil temps of 56F there's a good rationale for insulated foundations, including sub-slab insulation.

It's more than just an energy use issue (and it certainly is at least that), but also it's a mold hazard issue for the things resting on that floor, say a rug or a box. If your average summertime outdoor dew point temperatures are north of 50F it's worth putting at least R4-R5 under the slab when your subsoil temps are that cool.

If the subsoil temps were 65F there's still a good rationale for foundation wall insulation (though perhaps ICF would be overkill), but not so much under the middle of the slab in an air-conditioned house.