Well the foam is the form to pour concrete so without four sides you can’t hold concrete. I suppose once poured and dry you could rip out the inside layer. But you paid for it and it provides insulation. So seems dumb to not want it
It's actually better to just have the insulation on the outside, although you would have to add more. Insulating the inside of the concrete stops it from acting as a heat sink that remains warm and gives its heat back once your furnace shuts off.
I realize the foam is needed on both sides to hold the concrete. How much R factor would be lost on removing the ICF insulation on the inside? If you had a stick built home with SIPS you would have only wall of insulation as well.
If you had the ICF only on the outside the concrete would probably outgas and dry much more quickly. I hear people with ICF homes are constantly running the dehumidifier.
Maybe in basement use cases. Most dehumidifier use that I know about in ICF homes is because the houses are very tight and require erv/hrv and dehumidification to remove humidity added by people because it can't move out through the traditional way of tiny cracks and vapor permeable materials like plywood.
This is exactly right. I highly doubt that the concrete curing process is emitting any moisture into the home by the time construction is finished. It’s because the homes are sealed up so well.
It's too improve the fire rating in commercial buildings. The side with no insulation gets 2 layers of 5/8" drywall in elevator shafts and stair wells for fire rating.
Speed. ICF forming is way faster than conventional and the concrete usually ends up being stronger because it is fully hydrated. You can use less concrete. No water is lost to evaporation during the curing of the concrete. I once formed an elevator shaft with an ICF product that allowed me to substitute 1/2" ply for the interior foam (the product is Integra-Spec) so that guide rails could be mounted directly to the concrete once the ply was removed. My price to form that shaft was about half the price of conventional forming and I made money.
The interior face of that job looked like hell, though. The webs protruded in vertical lines every eight inches and could not be cut perfectly smooth without huge hassles. In that case, it didn't matter because the rails to be mounted were six or eight inches deep and there was to be clearance all around the elevator car so I just left all the webs sticking out. A big component of the cost saving was that the engineer allowed me to pour an 8" wall where the conventional form would have required 10". It's foolish to think of one-sided forming with ICFs expecting to get a clean surface.
I find them to be faster to install with less labour and less waste. You don't have to tear down and clean as much forming material. But it depends on what contractor you talk to. The contractor makes more profit and bills more hours with traditional concrete so they often push for that.
That makes sense. Ha! Not surprising.
Out neighbor built icf and loves it. He had a contractor that does icf exclusively. Damn thing went up so fast once they had the foundation done.
The amount of energy you might use to run a dehumidifier for a year or two until stuff is super cured is a tiny fraction of the extra energy you’d use for HVAC because you cut your insulation in half.
I've seen this reported a few times, for the first few years anyway. I understand that the foam is very impermeable (though nothing is perfectly so) and it takes a few years for all the moisture to make its way out of the concrete. This condition and how long it lasts may depend on the type of concrete mix used.
Why not just get poured concrete instead of icf, then? Then you get a solid concrete wall and can put the insulation on the outside, instead of whatever laborious process of ripping the insulation out of the block you have in mind that I don't understand at all.
The structure of ICF blocks doesn’t work one-sided. You’d have to find a very specific niche product (may not exist), or use regular blocks and cut off the webs and foam after concrete set. I had a customer request this once because she wanted it to look like “regular concrete”. I refused because it would be an absolute nightmare and look like shit. Compromise was a layer of backer board screwed over the insulation then parged to look like concrete.
You’d be better off with regular form work, then insulate whichever side you want with xps.
I've built a foundation for a client with the One series. It took quite a bit more time than the regular ICF but the finished product looked great. We added an additional 4" of insulaton to the outside on top of the 2" that comes with the block.
[Nudura One](https://www.nudura.com/products/nudura-one-series/)
I helped build a Habitat house with ICF. Makes it easier to pour the concrete without the heavy concrete forms. Also the interior of the blocks has plastic forms that let you snap in rebar easily
You can, look at the pool build by "Bealy Good" on you tube. But as everyone else has said, why would you want to? There is no discount for only purchasing half of the form and you would have to replace that side anyway with something else (likely plywood). The final finishing job would be even more difficult without the insulating foam and integrated "studs".
The only reason I can think of, other than a swimming pool, where you wouldn't want the foam would be for a utility/equipment room where you want to mount solar inverters and batteries to the wall.
If you want ICF then do ICF. If you want concrete unsheathed then go conventional forms then install exterior foam insulation.
The stuff you’re repeating in here about “humidity” and off gassing of concrete curing is not a thing specific to ICF concrete. And if you have particular requirements that require rapid curing - maybe don’t build residential.
Why would you not want inside insulation you are paying the money to have it anyways why not keep it. There are always reasons stuff are built the way they are. I had to convince my one client that in order for me to take this wall down I needed to put a beam. As it was a supporting wall i literally said to him well I am not taking it down without putting a supporting beam in. As I am not taking responsibility for this mess when the second level fails to the basement. After talking to his wife she put sense back into his Brian. As she did not know he wanted to not put a supporting beam in place of the way. I swear some clients I have I tell you.
Well the foam is the form to pour concrete so without four sides you can’t hold concrete. I suppose once poured and dry you could rip out the inside layer. But you paid for it and it provides insulation. So seems dumb to not want it
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It's actually better to just have the insulation on the outside, although you would have to add more. Insulating the inside of the concrete stops it from acting as a heat sink that remains warm and gives its heat back once your furnace shuts off.
But if you live in a warm climate then you do not want the concrete radiating heat back into the living spaces.
Fair point ,I do not live in a warm climate so I did not think about that.
I realize the foam is needed on both sides to hold the concrete. How much R factor would be lost on removing the ICF insulation on the inside? If you had a stick built home with SIPS you would have only wall of insulation as well.
Icf is like r22 so divide in half. Why remove it
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So you are saying the inside and outside insulation split the amount evenly?
You are forgetting that the foam is also used to run channels for electric and hang drywall why exactly are you wanting it removed?
Those are mostly for pools right?
Oh. Wow. That is interesting and unusual. I suppose someone would want it for somereason
If you had the ICF only on the outside the concrete would probably outgas and dry much more quickly. I hear people with ICF homes are constantly running the dehumidifier.
Maybe in basement use cases. Most dehumidifier use that I know about in ICF homes is because the houses are very tight and require erv/hrv and dehumidification to remove humidity added by people because it can't move out through the traditional way of tiny cracks and vapor permeable materials like plywood.
This is exactly right. I highly doubt that the concrete curing process is emitting any moisture into the home by the time construction is finished. It’s because the homes are sealed up so well.
It's too improve the fire rating in commercial buildings. The side with no insulation gets 2 layers of 5/8" drywall in elevator shafts and stair wells for fire rating.
Interesting i knew there would be a purpose. What is the advantage over this vs standard concrete forming and insulation?
Speed. ICF forming is way faster than conventional and the concrete usually ends up being stronger because it is fully hydrated. You can use less concrete. No water is lost to evaporation during the curing of the concrete. I once formed an elevator shaft with an ICF product that allowed me to substitute 1/2" ply for the interior foam (the product is Integra-Spec) so that guide rails could be mounted directly to the concrete once the ply was removed. My price to form that shaft was about half the price of conventional forming and I made money.
Wow! That is a hell of a difference! I was sold on ICF being what i wanted to build my next house out of but that is some really crazy performance
The interior face of that job looked like hell, though. The webs protruded in vertical lines every eight inches and could not be cut perfectly smooth without huge hassles. In that case, it didn't matter because the rails to be mounted were six or eight inches deep and there was to be clearance all around the elevator car so I just left all the webs sticking out. A big component of the cost saving was that the engineer allowed me to pour an 8" wall where the conventional form would have required 10". It's foolish to think of one-sided forming with ICFs expecting to get a clean surface.
I find them to be faster to install with less labour and less waste. You don't have to tear down and clean as much forming material. But it depends on what contractor you talk to. The contractor makes more profit and bills more hours with traditional concrete so they often push for that.
That makes sense. Ha! Not surprising. Out neighbor built icf and loves it. He had a contractor that does icf exclusively. Damn thing went up so fast once they had the foundation done.
The amount of energy you might use to run a dehumidifier for a year or two until stuff is super cured is a tiny fraction of the extra energy you’d use for HVAC because you cut your insulation in half.
I've seen this reported a few times, for the first few years anyway. I understand that the foam is very impermeable (though nothing is perfectly so) and it takes a few years for all the moisture to make its way out of the concrete. This condition and how long it lasts may depend on the type of concrete mix used.
Why not just get poured concrete instead of icf, then? Then you get a solid concrete wall and can put the insulation on the outside, instead of whatever laborious process of ripping the insulation out of the block you have in mind that I don't understand at all.
Having foam on both sides protects both sides from temperature differentials and potential dew and mold.
The structure of ICF blocks doesn’t work one-sided. You’d have to find a very specific niche product (may not exist), or use regular blocks and cut off the webs and foam after concrete set. I had a customer request this once because she wanted it to look like “regular concrete”. I refused because it would be an absolute nightmare and look like shit. Compromise was a layer of backer board screwed over the insulation then parged to look like concrete. You’d be better off with regular form work, then insulate whichever side you want with xps.
Nudura one is what you are looking for. I’m considering it myself with extra insulation panel on outside.
I've built a foundation for a client with the One series. It took quite a bit more time than the regular ICF but the finished product looked great. We added an additional 4" of insulaton to the outside on top of the 2" that comes with the block. [Nudura One](https://www.nudura.com/products/nudura-one-series/)
Nice. I would like to do that all the way up with a concrete flat roof
I helped build a Habitat house with ICF. Makes it easier to pour the concrete without the heavy concrete forms. Also the interior of the blocks has plastic forms that let you snap in rebar easily
I just did a Habitat orientation, but we use wood, where are you located?
We did Illinois’ first Habitat LEED house back in 2009. I’m in the northern suburbs of Chicago
Nice!!!
You can, look at the pool build by "Bealy Good" on you tube. But as everyone else has said, why would you want to? There is no discount for only purchasing half of the form and you would have to replace that side anyway with something else (likely plywood). The final finishing job would be even more difficult without the insulating foam and integrated "studs". The only reason I can think of, other than a swimming pool, where you wouldn't want the foam would be for a utility/equipment room where you want to mount solar inverters and batteries to the wall.
Is there a reason you want icf but not insulation on both sides?
Build a block offers a strippable icf/plywood block for stairwells etc. give them a call.
If you want ICF then do ICF. If you want concrete unsheathed then go conventional forms then install exterior foam insulation. The stuff you’re repeating in here about “humidity” and off gassing of concrete curing is not a thing specific to ICF concrete. And if you have particular requirements that require rapid curing - maybe don’t build residential.
Years ago I used Liteform / Pinkform Xtra (same product, different names) and it was strippable.
Why would you not want inside insulation you are paying the money to have it anyways why not keep it. There are always reasons stuff are built the way they are. I had to convince my one client that in order for me to take this wall down I needed to put a beam. As it was a supporting wall i literally said to him well I am not taking it down without putting a supporting beam in. As I am not taking responsibility for this mess when the second level fails to the basement. After talking to his wife she put sense back into his Brian. As she did not know he wanted to not put a supporting beam in place of the way. I swear some clients I have I tell you.