Never used them or seen them used. Apparently there's not much demand for concrete houses in New England.

The 40% energy savings claim is meaningless without revealing to what wall design the ICF wall system is being compared. The ICF system would have to be compared to a pretty poorly insulated wood framed wall system to achieve a 40% savings for the whole house (is the roof concrete too?) Therefore, I would assume the number is grossly exaggerated. Remember that the additional cost of the ICF system must be subtracted from any energy savings before a net cost savings can be claimed.

Also, I would think that a poured concrete wall system would be considerably slower to build than wood framing based on my experience building many larger PIP concrete buildings.

And then there is the difficulty of making changes during construction and later. I have recently done several major renovations to houses I designed new or renovated 18 to 20 years ago.

Where are you getting this information? Be skeptical of anything from industry organizations and suppliers. Find an architect who has used the system enough to know the advantages and disadvantages. No building system is a slam dunk; they all have limitations.

mav has it right. the 40% savings is against an old leaky house.
icf is great tech if you need it. like in hurricane areas. it is expensive and unforgiving. mistakes are not easily corrected. make sure you hire an experienced builder. icfs are no place for on the job training.
if i were you i would look at sips instead unless you live in a hurricane area.

I like the idea of ICF (of course, I live in hurricane country). They are very strong, very well insulated, and there is usually very little air infiltration. The concrete has a heat sink effect, slowing the change in temperature much more than insulation would. Living in an uninsulated concrete house, I can vouch for that effect with concrete. It also makes a very quiet house- you really can't hear much outside. They are obviously termite and rot proof, although it is claimed termites can tunnel all the way up to the roof, undetected under the foam. I can't vouch for that. All that being said, they are more expensive, and do have some drawbacks, such as being hard to make large changes after it's built. They CAN be built pretty fast, although framing can be done quickly, too. And both methods still need a roof. There are some serious pitfalls if not installed correctly, probably the worst being entrapped air in the concrete. There are various ways to vibrate the air out, but it takes skill and experience. As vhehn said- not the material for on-the-job training. If money were no object (alas, it is) I would build my foundation out of ICF, then the walls and roof out of steel SIP's. For more in-depth info, you might want to read the forums at greenbuildingtalk.com. Be advised that there are a lot of professionals there who are trying to convince you that their particular method is best, and take it with the appropriate grain of salt, but there are lots of good discussions there.

To get stick framing anywhere near ICF R value, you would have to use foam in all of the outside walls. Foam is VERY exp and would probably be more exp. than using ICF. In this area, ICF turn key job runs approx. $11-13/sf of outside walls using 6" blocks. This is labor, ICF blocks and concrete.

Thanks MACV, FLGARGOYLE & VHEHN - I don't live in a hurricane area, I live in Melbourne, Australia. The building down here I find very lacking and people are satisfied with what I call crappy building materials. I started looking into the ICF (& also Hebel Panels) because I wanted a solidly built home and what better material to do that with then concrete? lol Lots of builders here are still using foam on the exterior, then rendering it. After living in the South for 12 years and having to rip out all my front windows because of rot, you won't find me using the foam.

Then you have brick, sandstone, polystyrene, siding or stone. The labor costs here are unreal. Just to lay manufactured stone the product is $90 a sq meter and the labor is $145 a square meter! Heck, it would be easier for me to fly out someone from the states, give them a free vacation in Aussie for a bit of work on the house. I have certainly started looking into bringing my own hardwood flooring in. Real wood they want $80-$145sm and about another $55 to lay, a decent engineered can cost just as much.

We are using just about our whole building envelope and the walls would only be the exterior walls. We have a large Alfresco and a Patio under the roof line overlooking Melbourne that can be closed in later if a new owner wants more interior space. We are putting in automatic Cafe Blinds so that we can close in when we need to. The house is 3200sf with another 600 with the alfresco & patio.

I like the quietness of the ICF and the bug resistance. Of course it does all depend on your windows, roofing insulation, etc... You can have different thicknesses, depending on your budget. I have found a builder that only builds these types of homes, and his houses are typically at the top end of the market - $2 million plus.

But I will be doing alot more research before making any decision. As always, thanks for your guidance :-)

I wish you lived here MACV, I'd have you doing my house!!

Thanks to you too, Robin0919. :-)

Here is a link that has a lot of information on ICF construction.

http://www.greenbuildingtalk.com/

I wish people would stop saying an ICF system "performs like" an R-50 wall. There are reasons to use an ICF system but that claim is not one of them.

The OP lives in Australia. Tell us why an ICF system would be appropriate there and leave the voodoo-science to the manufacturers and the organizations they pay to publish it.

We used ICF for our basement/foundation and stickbuilt on it. The added cost was about 3K more compared to using another type of concrete forms to pour the foundation. Our reasons for using ICFs were the insulation value, the ease of doing 9' walls for the basement, comfort/reduced dampness in the basement and ease of finishing the interior walls of the basement as compared to having to fir out the walls to attach sheetrock.

We don't live in hurricane area by any means but basements are very common here. I would estimate probably about 40% of the new construction homes are done with ICF foundations with stick-built homes on them. Most contractors in our area are familiar with using them, although of course some are better than others. There are A LOT of different types of ICFs and any claim supporting them needs to be evaluated carefully to compare apples to apples.

My advice would be to list out your main reasons for considering an ICF house and posting it here -- I'm sure people will weigh-in with opinions on whether an ICF house would really chieve what you are hoping it will and also may have come otehr suggestions of how to accomplish your goals. Good Luck!

LOL, really the only reason I want one is for the solidness of the house, and the inset windows and doors. Saving money on energy costs would be great, but that is by no way my driving factor, I really don't care about that.

I want a stone colored house (similar to color of cement) with black trim. That means not putting on brick and leaving it natural.

The brick choices here in Aussie, I would have to say, are a bit lacking, compared to our choices back home in the South. I have been to the two big brick manufacturers and there is nothing I would truly love to put on the house. I would be settling for something and I am not a settler.

Like I stated above, most builders use foam as the siding and render over it. I am not comfortable with this choice and would rather spend a bit more and have a very solid home. The noise reduction will be nice too....hhmmmm....maybe I can have them wall in my 11 year old son's room and then he can fire his capguns in the house all he wants. :-)

So because of that reason I am looking at either the ICF or the Hebel Panels. The Hebel rep has given me a price of $125 square meter for the product, labour and rendered. Brick here is anywhere between $90-$110, siding $60-$85 but then you have to still paint it and the foam is $75'ish and then again you have rendering and possible painting. All these (except foam) you still have to add insulation, and other materials, where with the ICF its all done.

There is a builder here that specializes in ICF homes, so if I went this route, I would obviously go with him.

But because MACV is not thrilled with the product.....

Macv, OK, how to say this politely. You pretty much don't know your arse from your elbow. There. Sorry, but your lack of familiarity with ICF as well as other areas in GW where you post dozens of times an hour should be predicated with "This is just my opinion". Some people are looking for objective info.

That's polite? Petty personal attacks are not appreciated here.

What you call "research" regarding ICF energy conservation indicates you are simply repeating what you have read on the internet and that's neither objective nor accurate. But you did agree with me about the speed of construction and higher cost.

I don't see you prefacing your comments with "This is just my opinion".

I suggest you offer your own opinion, keep it civil and avoid hypocrisy.

My opinion:

I like ICF (or masonry with EPS insulation) much better than wood stick framed because the house is (not my opinion but fact) stronger and feels so much more solid. I like the much higher thermal mass and that the house is not leaking (precious conditioned) air. It is also not termite food and won't rot.

If solid construction, hurricane resistance, air infiltration, rot, mold and termites are of no concern then I guess wood sticks are good enough.

Macv. Fair enough. My apologies. GW is all about opinions.

It's all about geographic location and what works in your area. That's where research should be concentrated not fully dependent on internet forums which typically generalize.

I would think ICF's would work in any area/condition. What's in your wallet? Similar results can be obtained with stick built walls dependent on the conditions of your build. You could say that a traditional three coat stucco over a framed wall is a form of ICF.

ICF is a good wall system if it is for certain needs.

ICF is not equivalent to R50 walls unless you use special thicker insulation.

Dollar for dollar ICF walls are the highest costing insulation there is.

Thermal mass is not really a big factor in an ICF home because the interior insulation inhibits the thermal flywheel.

ICF is a solid, quiet home that if done properly will be great to live in if it also meets all your other criteria ( cost, finishes, needed r-value etc.)

"I want a stone colored house (similar to color of cement) with black trim. That means not putting on brick and leaving it natural."

I'm not sure what you mean by leaving it natural. The exterior of our ICF was a blue foam - part we covered with stucco (they did an awful job), the rest was Hardi (great subs, but costly). I'm not sure if I would do ICF again or not. Our contractor lied to us about the costs/benefits - that being said, I do love the solidness of our house, the temperature does seem more stable than any other house I've lived in. And since we rebuilt after Katrina, the resistance to hurricanes is a huge factor for us.

Without the possibility of flooding, I think SIPS is probably a better way to go. Flooding may or may not be an issue with SIPS, but at the time I was researching, I didn't find any data that said it would/would not be a problem - so ultimately we went with ICF.

Carterinms: Sorry for the confusion, what I meant by natural brick is brick left alone, as it is put up, not rendering it. Seems like a waste of money to put a brick home up, rendering it, then painting it. It's ok if that is the look you are looking for, which is wonderful on the right house.

The house we are building is contemporary, which our Arch. Guidelines stipulate. I am not a contemporary person at all, so I am trying to get a look that I can live with.

I value MACV's opinion, he is always clear, concise and accurate. No home is perfect for everyone, it just matters if it is perfect for you. Energy savings depends on where you live, how the house is placed, how many/how big are your windows and what is going on in your roof. I have LOTS of windows, because of the views, so I kinda counter any savings I might get with the ICF, but it would be a solid house, regardless, and that is what I am after. Now the question is.......am I willing to pay for it? I'll know next week.

We all have opinions, and usually we have experience behind those opinions :-)

We built an ICF house and love it for all of the positive reasons stated by others above. It was expensive, but DH wanted a very tight house and wanted it as energy efficient as possible (operating costs, not building costs!). He did LOTS of research, and found that the R50 claimed was only true in hot climates like the SW. In our cold climate, I think it is around an R30.

It definitely is not a quick build! He watched an experienced crew of 8-10 guys build the ICF part of a high end house,and it took them several weeks.

DH and another experienced guy put up most of our ICFs (putting in the rebar and bracing everything well add to the time), and you don't want to know how long it took the 2 of them, working 12 hour days, 6 days a week! Of course, that includes DH talking to potential subs on the phone, analyzing EVERY situation with the 2nd guy, and stopping to explain to neighbors and friends everything he was researching about energy efficient houses, government policies, etc.

Anne

Here's how "effective R Value" works:

If your neighbors use fuel oil and you use natural gas for heating they might be paying a premium of 20%. If your houses have the same walls with R-11 insulation, you could say that your lower heating cost is equivalent or effective to having additional insulation. Then you could multiply R-11 by 120% and say your "effective R Value" is R-13.2

If your high performance car gets 20 MPG you could buy lower octane gas for a 20% savings, let the engine computer retard the ignition timing, and say your "effective MPG" is 24.

If a typical ICF wall has an R Value of 22 and a 2x4 wall with fiberglass insulation, 1/2" sheathing and building paper has an average R Value of 9.5, you could run a computer simulation that would say the cost savings in a hot dry climate was 35% and claim an "effective R Value" of 30.

If you upgraded the stud wall to double 2x4's with 8 inches of insulation, added a spray-on liquid air barrier, and changed the location to Chicago, the computer simulation should say the energy cost is equal.

If you were willing to allow the exterior framed wall to be as thick and expensive as an ICF wall, the energy savings for the wood framed system could be substantial.

But don't take my word for it, read some computer modeling and field testing studies.

This is a link to Energy Use of Single-Family Houses with Various Exterior Walls.

The Journal of Light Construction is a good source of professional level information. You can view comments but only professionals can join. The best comments are often from Martin Holladay.

This is a link to comments on the JLC forum.

The NAHB and HUD did a study and found that:

"In field comparisons of similar ICF and wood-frame house constructions, it has been found that ICF wall construction can provide a 20 to 25 percent savings in annual heating and cooling costs3. To achieve a similar level of energy performance, a typical wood-frame home would require an "energy upgrade" that adds about $2,640 to an average home cost of $200,000 (or about $1.32 per square foot of living area). This amount is equivalent to about one-third of the cost difference between ICF and typical wood-frame house construction."

Avoid websites like the one for Rewards Wall Systems that says:
"To match this ICF energy performance, the wood frame house would need to have an R-Value of at least 125 in the colder climates and, in effect, some number over 1,000-the top of the R-Value scale for the warmer climates."

You don't need any more evidence than the above quote to know to ignore the claims of ICF installers. Imagine having to build a wall 25 ft thick filled with fiberglass insulation in order to be equivalent in energy use to a foot thick ICF wall.

If you want the most appropriate building envelope and mechanical systems for your climate and don't want to hire a professional to help you, I recommend buying a copy of Mechanical and Electrical Equipment for Buildings and reading it carefully and repeatedly. I used the 4th edition in grad school and try to buy a new edition every decade. Remembering and applying this information to designs with all of the possible variables is very difficult so my current copy is full of post-it notes and yours should too.

Of course if you live in tornado or hurricane territory energy conservation shouldn't be your top priority when choosing a wall system.

Here is a link that might be useful: the book

MACV: You are a WONDER!!!! Thanks for that. So, if I want a solid house, ICF or Hebel Panels can be the way to go.

If I want an energy efficient, yet cost efficient, I should:
(1) frame with 2x6's,
(2) put in really heavy insulation,
(3) tinted low E windows because the back of the house is more windows than walls and is my North facing wall
(4) clad with either brick, (probably the best?) render (stucco) or Fiber Cement Siding.
(5) make sure I have really good insulation in the roof
(6) roof choices are either cement tiles or Colorbond Steel. Asphalt shingles are not used here, but just starting to come to market. if I used them I would be the only one in the whole town that has them.

The house has to have a Five Star Energy Rating, otherwise I will not get my Certificate of Occupancy. However, seeing the crappy construction that is done, it doesn't seem to be too hard.

Like I said before, I am after a solidly built house. The current house I am in is a Melbourne 1920's Edwardian Wood Cladding home that has a side gate next to the Master Bedroom. Whenever we get wind and the gate is unlatched, it blows open against the wall and shakes the whole thing. You don't just hear it, you feel it to, down to the foundation. Drives me fricken nuts!!!

I'd just like to second everything macv says. Claims by manufacturers are pretty suspect in the building world - no FDA I guess. Whether it is foam, ICF, geothermal - the quotes on cost savings are always exaggerated. Even the energy consultants are to be questioned. We had a $1400 a winter heating estimate. It was closer to $600 with a very cold winter (ng was $200, electric hard to figure in our first year especially with a heavy a/c requirement) . Now - did I do somethings to make that happen - sure. Does that mean I can claim I saved 60% over the reference house - not really. Mind you that reference house was new construction. Call your reference average housing stock and the estimated heating bill would be $2000. So I can get geothermal and ICF like savings with a 2x4 constructed house - call me a miracle worker....

Just moved in to our ICF house from a stick built tract home.
We live in the south east where the heating season is longer and humidity is also high. The biggest difference I've noticed is the great improvement in humid air infiltration. In a stick built home often you put the ac on just to eliminate the humidity not necessarily the heat. With ICF, we just don't feel the humidity. How much this will translate into savings we're not yet sure, since we haven't received an electricity bill yet (using geothermal). However the comfort level is terrific.

Can't wait, DOCTJ, to hear what you say in another month or so. We have not made a decision yet. I am now looking at the SIPs, so we will see. I think we just lost our builder on this house so we might go ahead and owner build instead. If so we will hire a project manager to make sure everything is done in accordance to sound building practices.

I just replied on your other thread, and then saw this. I missed that you DO have access to ICF-experienced builders in your area. That being the case, I would definitelyt consider it along with whole-house SIPS....maybe get comparisons for cost for your area. Our ICF is foam blocks that interlock like legos, it's 2-inch foam on each side with solid concrete walls poured down into the gap. It was a hassle to get built because we didn't have experienced crew, but once they got all the windows and doors rearranged so they were the right size and in the right places ;~) (I strongly recommend going out with your plans and measuring all door and window locations before they do the pour!) the house is wonderful to live in. We've found the cost savings for cooling a bit exaggerated but the comfort level is extraordinary. Humidity isn't as bothersome, and there are MANY more days out of the year when we don't need any a/c or heating for the house to remain comfortable. In a standard-built house, we pretty much used our a/c seven or eight months out of the year (and sometimes in the winter, because we have 70s and 80s alternating with 20s or below, you just never know about "winter" here!) My point is that sometimes it's really cold, and I love not having drafts....but more of the time it's hot and humid and I love being cool and comfy. If ICF is affordable in your area and there are experienced builders, ICF walls and SIPS roof panels can be a great combination. We also love how quiet it is, and when we have screaming high winds a couple of times a year, it's kind of nice to know how solid the walls and roof are!

Very happy to report back. My electricity bill was $20 lower than for my previous house for the same time last yr. My current house is 4x larger including the basement! In addition this month has been unseasonably hot averaging 90f when it's usually in the mid 70's to 80. I believe the basement contributes a lot to this, the average temp there is high 60-70's I put the system fan on for all three floors and this circulates the cool air throughout the house. With very little heat loss through the walls and low e glass, we hardly need to put on the geothermal except for the second floor towards the end of the day. Delighted with this plus the comfort factor and quietness is unbeatable. I don't think I'll ever build another house without ICF.

We are building an ICF "logix" home right now. I am very impressed how solid it is... obviously it's concrete walls! Once you hear about it you find out more and more people are building this way. I think it is fantastic and am excited the reap the benefits!

To briosafarm and doctj:

You're both saying that there are many days you don't need either AC or heating, but I assume you still need the fan blower on the system working for the IAQ, right? Do you guys have ERVs?

Another thing I'm not getting a grip on when it comes to ICF is the humidity? Why is it lower, is it because of the ERV?

As background I'm also very interested in ICF, I like the sound proofing, termite protection and energy savings, but we are planning so many windows (and a NANA wall) so I'm not sure it makes sense anymore.

Another thing I would like to ask those of you with serious experience of ICF, although this is perhaps more something a builder would know, but have you experienced that ICF walls get wavy? In my research I spoke to a SIP installer (I know, but you have to admit the competition is usually phenomenal when it comes to finding potential pitfalls with other systems) and he said that it's virtually impossible to get walls straight and plumb with ICF, the way you can correct and adjust with SB and SIP. He claimed that it was hard to get the forms perfectly straight to begin with, they sort of move or have a slight play that over several courses makes the wall 'wavy', especially on longer/higher walls. This apparently gets worse once they pour as the pressure forces the light forms around, especially around scaffolding. The effect can be dramatic if you have walls with lots of cabinets, etc.

I don't know what to think, and I've never heard about this before. It sort of makes sense but I thought the reason for scaffolding was support for blowouts, not the alignment? Anyone heard anything about this?

lordnelson, as I mentioned in my post I do use the fan to circulate the cold air from my basement through the entire house. My geo installer stated it's very cheap to do that. My geothermal system also has a dehumidifier which also contributes to the low humdity.
Unlike a stick built home where there is interruption in whatever insulation you're using every 16" on center that allows air infiltration, this is absent in icf/sip homes. We have a lot of windows in our house, a two storey great room with five windows and a double patio door but we bought higher grade Pella which seem to be working quite well. I may attach some pictures on this thread later if I have time.
In terms of bowing, I haven't seen that and we have a forty foot wall in the master, however our tile installer did have more difficulty on the icf walls than the interior walls. Having said that he wasn't particularly good so I'm not sure how much of it was due to the installer's inadequacies.
Hiring a skilled icf installer is key to preventing blowouts and bowing.

Sometimes we use the a/c for a while just to take the humidity out of the air, or turn on the ceiling fans or turn the system fan on to ciculate....but we notice there are a lot of periods during the year when we don't need any a/c or heating because the house just stays comfortable and doesn't trip the thermostat to do anything. For us, those periods are generally spring, fall, and quite a bit of time during the winter because our winters are variable. Hubby would like to add a whole house dehumidifier, because that would translate to even less need for the a/c at times. We also have geothermal well bores and heat pump, which are very nice for the a/c and the heating system.....but the ICF walls do make our need for use of either system quite a bit less than the standard houses we lived in before. We have LOTS of windows and lots of full glass doors, but still feel the ICF walls make a big difference in the comfort level of the house. I don't have any way to tell how much is the ICF walls and how much is the SIPS roof (and so the attic is not vented and stays much cooler all the time) but the combination is wonderful.

Re: wavy walls....hmmmmm, I thought that was what the bracing and levels were for. ;~) Those forms need to be put up pretty squarely and braced pretty well for things to work properly during the pour, but they *should* be braced securely enough that the forms couldn't wiggle and the wall wouldn't end up wavy. Not saying it couldn't happen, but there are also opportunities with the foam cladding and the drywall and the finishing to correct or straighten up an interior wall discrepancy if one occurred.

briosafarm, I agree in the last week temps dropped to the 70-80's and we hardly used our geo. Ceiling fans alone were adequate.

Also whether you decide to use sips or icf, definitely get a geothermal system. With the tax credits it will cost the same/cheaper than a conventional system. In my case it will be cheaper because I will receive both state (NC) and federal credits which make it $6k less than the quote for a conventional heat pump/forced air system. Higher upfront costs but you get the difference back when you file your taxes for the year it was installed.

Thanks to both of you for the info, sounds very promising.

As for the fan blower, I guess I'm more wondering about fresh air from outside than temperature. I would assume that if you don't use the fan regularly, and without fresh air injection from an HRV or ERV, you would get an air quality problem with such a tight house? Or is it perhaps a given to have an HRV or ERV that runs continuously?

In my system fresh air is brought in periodically.

In mine we just open the doors a lot to let the dogs in and out. ;~) Sometimes when the weather is nice I open the windows and use the whole house fan to pull air in through the windows and exhaust it out the top of the house...another nice feature for energy efficiency and flexibility, depending on the weather. Seriously, the question of air quality in a tight house is a good one, and one I hadn't thought a lot about. I think we don't have a problem partly because as I said, we do have things open a lot. We have the ICF, SIPS, geothermal, etc. to help counteract the fact that we do have lots of windows and that windows and doors are open a lot...helps balance things out as far as energy consumption.

I'm curious as to how that works though. In such tight houses I would assume that the blower would have to run a certain time every hour, with a connection to fresh air, to avoid bad air in the house.

I guess part of concern is what happens if there is power outage etc, a bit scary to be dependent on mechanical breathing. But that's perhaps part of life in modern buildings and something that isn't unique to ICF.

briosafarm:

I just saw that my mail came after your response. I actually wrote it before but forgot to press submit until later. So that's how you do it then. Have you been through a winter yet, when you're not having the windows and doors open?

Been through 4 winters and a couple of really cold spells, but for us the most "shut up" time of the year is the long hot summer period where for three months (at least) we wouldn't dream of opening a window and open the doors as little as possible so things will stay cool. My response about letting the dogs in and out was sort of joking (but true as well!) LOL When we were building we did a lot of research and hubby worried about the fresh air issues with a very tight house. What we found was that in practice, it is very difficult to build a house tight enough for air quality to be a real issue. It's been done, but in most homes as a practical matter, you just can't get a tight enough envelope for air quslity to be a significant problem. For us, knowing we wanted lots of windows and doors, a fireplace, really good exhaust fans in bathroom and utility room, a dog door, etc. we wanted all the extra "tightness" and insulation we could get, to counteract all those penetrations...thus the ICF walls, the SIPS roof, good quality windows, a fireplace with a good sealed damper, etc. I live with animals so really notice if the air isn't fresh or changed out often enough. At least for us, all the things to make it tighter were to counteract the things we knew would be letting air in.

I guess this is the part I have a hard time understanding. I would have expected features like fireplaces and strong exhaust fans in kitchen and bathrooms would require some form of mechanical makeup air in such a tight house. With ICF, SIP roof and quality windows it sounds like your house is as tight as it gets. Do you mind me asking how big your house is?

Nope, don't mind. We are almost 4,000 sq. ft. Three bedroom house, not large bedrooms but the single living room, single dining area, kitchen are largish spaces with the sometimes-highly-criticized high ceilings everywhere. ;~) I love 'em! We have some square footage that most folks wouldn't want or need because we have a section of the house that consists of two office spaces and a "dog room" and a largish back entry area that also functions as mud room (partly because we work at home and partly because we live with dogs and this is what works well for us.) We also have a hugely high central hallway to be an "air chimney" with high windows that can open remote....when they are open they create a natural air flow through the house windows and up and out the high windows. Obviously our house is designed for a climate that is hot most of the year!

I wish I had a better engineering answer for you about why we haven't needed the makeup air, but I suspect it is simply because our house isn't as tight as hubby wanted it originally. We did a lot of research into ICFs and SIPs and tight houses, and had originally intended to design and add a makeup air infusion system. We did see some articles indicating that while it is possible to design and build a house tight enough to need makeup air, that in general "real living" some houses would not need it. In practice, we have not needed it, and that is probably because once I got through adding the fireplace (even though we chose the tightest sealed damper we could find) and the dog doors (though we can close off that room with a weather-stripped door when we want to) and we also have two vents for the whole-house exhaust fan (which are *supposed* to be sealed but probably aren't as tight as their specs)...well, basically anyplace you have a potential pentration like that probably lets more air in than you expect. Anyway, those exposures are probably why we haven't neded the make up air. We do have very strong exhaust fans (large Panasonic whisper quiet) in the bathrooms and in the utility room where the cat boxes are, and in the kitchen.....those seem able to work great with no makeup air...probably because of our "unintended" air penetration places. If I turn on the whole-house fan to exhaust, either in the main part of the house or in the "dog room" I can feel and hear the windows and doors suck in, and doors in the house that are partly closed will close....we definitely have to open some windows...so the house IS at least that tight. Does all that make sense? It's tight enough that we have a MUCH higher comfort level during cold spells (no drafts at all, floors stay very comfortable) and during very hot spells than any house we have lived in before; our utility bills are lower, our a/c is much more efficient during humid times. I think the nice tight envelope due to the ICF and SIPS and sealed attic,good windows, etc. just go a long way to making up for our other "air penetrations" caused by how I wanted my house to live (lots of windows and glass doors, dog doors, etc.)

Thanks for the thorough response. This information is so valuable since it is real life and not theory. As you can tell I'm really worried about bad air, and I've read quite a bit on the increased humidity from tight houses, not just from food and bathrooms but humans and plants as well, and on top of it VOC from paint and furniture. I wish there was a simple tool to measure air quality.

My wife was raised in an area with town houses built in the 70's, and had four friends that lived in the same row of houses, and they all developed allergies. Could have been completely unrelated but makes you wonder.

bump

Hi,

My neighbour's house is an ICF house. Built about 7 years ago by the original owner. The house location is Westchester New York. The original builder was also a builder and one of the first dealers in ICF. The house external walls are top to bottom ICF. The exterior of the house is cedar shingle.

I have been in the house many times. It is extremely quiet, shouting upstairs to get people for dinner just does not work. Temperature wise it is very stable. The HVAC compressors are sized smaller. The R-Value is high, not sure what, but also the big difference is termal mass. The concrete acts as a big heat sink. So stores energy during the day, and gives it out at night; just like those adobe buildings in the desert. It feels rock solid. No insect infestation issues, lower fire risk.

The few downsides include you have to plan in advance where everything goes. Putting up shelves means hooking into concrete. Wiring means having channels made into the polystyrene forms for wiring runs. This is easy when the sheetrock is notup. A wire heater cutter is used. But once the sheetrock is up, you cannot "fish" behind sheetrock to put more wires in.

Overall it is a lovely home.

best, Mike.