ICF's or regular poured walls?
- Thread starter P Dubya
- Start date
kd3pc
Well-known member
NO down side, other than cost and an experienced crew to build with them.
kd3pc.... I have not looked at the cost yet but they looked stone simple to work with... Kinda reminded me of Legos. As long as they are square and plumb on the footings I would think they would be not much different than laying a block foundation...? Sales guy at the home show said many people pour half the depth of the wall at a time to reduce the chance of a blow out in the form... That part doesnt really thrill me. Not sure if I like the idea of a seam/cold-joint in the basement wall....
gasgas17
Well-known member
We pour 4 foot lifts, but pour continuously so we have no cold joint. If you don't have the proper adjustable bracing, they take an incredible amount of wood to keep straight. Personally, I would pour conventional wall and frame with 2x4 inside and spray foam the wall and rim joist. Way less expensive and far better result imo.
wnstwolf
Well-known member
I used them for our new home about 2 years back and have no regrets. Local supplier assisted and with concrete contractors guidance my wife and I pretty much put the lego's together. We used logic brand and once first layers are in place and square your good to go.
You need lots of bracing during pour/cure which we rented and lots of rebar which we were a bit overkill. Our inspector had not dealt with icf before so we were all on learning curve. One item that bit us at the end was having the Sheetrock the basement before certificate of occupancy could be issued. No big deal as we would have done it but at that stage of building a new house we were broke and we now had to rock a 1,500 sq/ft basement.
Plan your electrical and other items ahead of time so you can avoid furring out walls. Box into form and then you can grove out later for wire runs.
Basement is now a few year old super tight good r value and very happy. Good luck.
You need lots of bracing during pour/cure which we rented and lots of rebar which we were a bit overkill. Our inspector had not dealt with icf before so we were all on learning curve. One item that bit us at the end was having the Sheetrock the basement before certificate of occupancy could be issued. No big deal as we would have done it but at that stage of building a new house we were broke and we now had to rock a 1,500 sq/ft basement.
Plan your electrical and other items ahead of time so you can avoid furring out walls. Box into form and then you can grove out later for wire runs.
Basement is now a few year old super tight good r value and very happy. Good luck.
rburke65
Well-known member
A friend of mine was going to use the ICF and took a 2 day class on the installation process. I'm sure the classes are out there.
gearhead9056
Well-known member
My basement was done with ICF walls and footings, the concrete floor is very warm and heat and AC are cheaper.
My dad and I also did our shop foundation with ICF, did about 6 foot wall. Alot of bracing is necessary and we still had a small blowout, but as far as I can tell that's the only downside
My dad and I also did our shop foundation with ICF, did about 6 foot wall. Alot of bracing is necessary and we still had a small blowout, but as far as I can tell that's the only downside
csp
Well-known member
My basement is also ICF and the warmth is what I notice compared to a standard form as well. It's a walkout, but we poured the entire thing instead of framing out the portion that's above ground. It's dead quiet too. No outside noise and no echoing within the basement.
As said, you have to brace the **** out of them with wood if you don't have the adjustable braces. We did three lifts with 10' walls.
As said, you have to brace the **** out of them with wood if you don't have the adjustable braces. We did three lifts with 10' walls.
MushCreek
Well-known member
Our house is ICF, and we love it! I did most of the work, with coaching from a local contractor who specializes in ICF. I rented bracing from him, and hired his crew to actually fill the forms. The filling and consolidation of the concrete are very important. Here's a link to my build thread:
http://countryplans.com/smf/index.php?topic=12170.0
http://countryplans.com/smf/index.php?topic=12170.0
Nice looking house MushCreek, be proud of that build.
PDub, if you haven't read Doug's Concrete Underground build in the Gallery Section, you might want to. He's a concrete contractor building a concrete house and did use some ICFs.
theoldwizard1
Well-known member
Got any data to support that statement ?
theoldwizard1
Well-known member
Proper exterior water proofing and drainage is still required. Also careful back filling is necessary to prevent damage.
csp
Well-known member
Good point about the backfill. My excavator said backfilling is a bit of a chore just to be sure they don't rip up the foam.
MushCreek
Well-known member
ICF walls are no different structurally than poured concrete walls. You should always have the floor diaphragm in place prior to backfilling. As with concrete, you should have waterproofing on the outside. I used peel 'n stick, then dimpleboard. I also backfilled most of the way with gravel to promote drainage, and have a french drain at the bottom to carry any accumulated water away before it ever reaches the foundation. Lastly, I have gutters to collect and direct the water off of the roof rather than letting it splash right next to the foundation. Our basement is dry, dry, dry!
wssix99
Well-known member
I am finishing out our build of a 4 story ICF house in Chicago:
BTW - That's my wife on the lift installing windows. She is still thawing (physically and emotionally) from last winter and the decks and interior finishes are on me to do.
What are you after here? Are you looking to pick a particular type of system, looking to do it yourself? What kind of structure are you looking at? (Based on those things, I can probably provide better information for you.)
In general, I'd say ICF construction is 50%+ more expensive than frame construction. That being said, this house is the most comfortable structure I've ever been in. (Residential or Commercial) It's certainly a luxury but also has some very practical applications, depending on the part of the world you live in.
It's not as easy as putting Legos together. The blocks are NOT perfect or uniform, so the process constantly involves making sure the walls are plumb and level. This requires gluing many of the blocks together and is more like working with huge bricks & mortar vs. putting Legos together. Curved walls, etc. are a different kind of hell but are breathtaking when poured in stone.
The other quirk to this construction are the control joints. Because the blocks are not perfectly uniform, you will have vertical glued seams in each wall to make sure the corners are in the right places: (We strategically located ours' in line with doors and windows. You'll see the plywood sticks we used to "stitch" and reinforce them together during the pours.)
(Please excuse the huge hunk of plywood in the picture above. That was our second blow-out. Fortunately, we got much better with that and only had one as we went up high - and that was a small one that blew in onto a floor, so we didn't have a mess outside at height.)
The killer with the control joints is that they throw off the "perfect" 8" spacing of the webs, which can be problematic depending on the type of siding you choose. Board/vinyl siding or stucco = no problem. Metal or vertical siding is almost impossible to do easily on this type of construction.
In addition to the factors above that slow things down, (time = money here) some of the costs go up as you go high. You need bigger pumpers, more crane time, etc. BTW - Carrying rebar up 40' of ladders *****.
If I was doing a 1 or 2 story house, I'd do it all again in a heartbeat. With such a tall house, I would probably look at doing standard form walls or a pre-cast structure and then applying foam to the outside. The insulation, maintenance, and air tightness of those two options would probably not be as good - but I would have saved enough money to put something in the garage afterwards. (The garage will be empty for some time!)
MushCreek
Well-known member
I used Fox Blocks, and didn't have any issues with dimensions. Of course, mine is a much smaller house, and only two stories (basement and main floor). The only part of mine that took some thinking was creating the door and window openings. My walls came out within 1/4" straight/square/plumb/level. Part of this is due to having absolutely perfect footings. I glued my first course, and glued the corners. Fox sells a clip to hold the blocks together so they can't float or separate.
There is a lot of discussion and controversy about the energy efficiency of ICF. My walls are rated at R-25, which can be easily bested by other methods. BUT- Done properly, the method is inherently airtight, which has been found to be a major contributor for energy loss. Concrete walls are a lot more likely to stay airtight than wood framing, which shrinks, warps, and wracks over time. Also, the thermal mass has a huge effect, but only at certain times of year. I was just reading a study that found that the R rating is true in winter and summer, but can run much higher during the shoulder seasons of spring and fall. It also makes a very strong, quiet house, and the walls are bullet proof, handy for the next zombie apocalypse!
There is no one ideal system, and different types excel in different climates. I spent 6 years studying this stuff before deciding on ICF, and one of the reasons I went this route is that I'm 61 years old, and working alone, so ICF was a good way to go. I would have needed help for any other system. The runner-up was steel SIP's. I recommend greenbuildingtalk as a good forum if you want to learn more about the various systems.
There is a lot of discussion and controversy about the energy efficiency of ICF. My walls are rated at R-25, which can be easily bested by other methods. BUT- Done properly, the method is inherently airtight, which has been found to be a major contributor for energy loss. Concrete walls are a lot more likely to stay airtight than wood framing, which shrinks, warps, and wracks over time. Also, the thermal mass has a huge effect, but only at certain times of year. I was just reading a study that found that the R rating is true in winter and summer, but can run much higher during the shoulder seasons of spring and fall. It also makes a very strong, quiet house, and the walls are bullet proof, handy for the next zombie apocalypse!
There is no one ideal system, and different types excel in different climates. I spent 6 years studying this stuff before deciding on ICF, and one of the reasons I went this route is that I'm 61 years old, and working alone, so ICF was a good way to go. I would have needed help for any other system. The runner-up was steel SIP's. I recommend greenbuildingtalk as a good forum if you want to learn more about the various systems.
wssix99
Well-known member
Yea, the problem magnifies with height, wall width, and thickness. Our base walls have 8" thick cores and I found those larger blocks were off more. Some of the corner blocks alone varied by 1/4". (We used Logix.) I also agree that the footings are key. We spent a lot of time to get them level and perfectly aligned. (We also picked dimensions to limit block cutting.)
This is all true and the air tightness and thermal mass are the big factors. 1 week after our first cold snap during construction, we found our plumber giving the column between our garage doors a bear hug. It had held on to so much heat, it was still 50 degrees after the air had fallen to 35 for a week. In the fall and summer, our heating/cooling costs are near zero because the walls constantly radiate the average daily temperature. We are seeing peak HVAC usage in the middle of summer and winter - but the spring and fall are nothing. (It's really entertaining looking at the graphs on our electricity and gas bills.)
My wife has built a number of concrete homes in "up and coming" neighborhoods and in some places, they really are bulletproof and that was in the marketing pitch. (That didn't stop the neighborhood kids from figuring out that they could still shoot out the windows, but they generally don't do that sort of thing once the house is occupied.)
We did the same and had to throw all that out the window when it came time to build. In the end our decision was made based on what our mason uses and the bracing system he has. He was set up and invested in Logix, so that's what we went with.
If we had the time (and experience working at heights - the risk of high altitude blowouts was too much to risk the learning curve) to do it ourselves, we would have picked Amvic as they offer a nice rental bracing system.
How have you finished the inside?
Looked into it when I was doing a small stucco house by the coast. The cost to prep for any other exterior finish was too expensive. Are you going with a stucco finish?
I did typical poured concrete walls/ interior spray foam
Looked into it when I was doing a small stucco house by the coast. The cost to prep for any other exterior finish was too expensive. Are you going with a stucco finish?
I did typical poured concrete walls/ interior spray foam
MushCreek
Well-known member
I just did regular drywall inside, and fiber cement clapboards over a drainage plane on the outside. There is an embedded fastening strip every 8". I did stucco on the exposed basement walls.
wssix99
Well-known member
Drywall on the inside for me, too. It just slaps up on the ICF. It's also useful to place plywood behind the cabinets and metal pieces where window treatments will install. (The webs every 8" can be tough to hit right through the cabinets.)
We've also found that closets up against the ICF tend to get a little musty. We think this is from the concrete curing. A little desiccant takes care of that and we expect the moisture to taper off over time.
On the outside, we have some engineered wood siding, sheet metal, and stucco:
We've also found that closets up against the ICF tend to get a little musty. We think this is from the concrete curing. A little desiccant takes care of that and we expect the moisture to taper off over time.
On the outside, we have some engineered wood siding, sheet metal, and stucco:
DougWil
Well-known member
ICF is a great system, avoiding form costs, but it really isn't very energy efficient.
The actually amount of insulation over an entire wall assembly is fairly low unless you go with a very thick wall.
Plus there is a lot of hype about 'equivalent' R values, which under most climates is bogus.
The actually amount of insulation over an entire wall assembly is fairly low unless you go with a very thick wall.
Plus there is a lot of hype about 'equivalent' R values, which under most climates is bogus.
ishiboo
Well-known member
They are rated at least R-22 actual, which is similar to what you get with conventional. But then subtract thermal bridging. And the fact there is ZERO airflow (also an advantage for spray foam). It's not just in the R-value numbers.
Not sure at what point if any it's more economically viable, but I think saying it's not energy efficient is pretty inaccurate.
ssdave
Banned
I've done two houses with ICF. After the first one, I said I wouldn't do another. But, the second one because of the hillside design really made sense, so I did another.
Pluses: It is air tight if you do the rest of the detailing right. It is very sound proof. Very energy efficient, partly because of the thermal mass and insulation, but mostly because of the air tight.
Minuses: It is very hard to get it all straight and plumb and level. You'll have to adapt your followup work to that. It is limited in how to attach things; you have to plan ahead. Electric wiring is a challenge, not insurmountable, but you have to plan for it. Siding it is a challenge. Good for stucco finishes, that was my solution both times. Biggest detriment is cost. It is just plain expensive, whether you do it yourself or have it done. If you DIY and don't count your time, the cost deficit is smaller.
I'm building another house now. I didn't even consider ICF. It's cheaper, easier, and you get an equivalent energy efficient product using 2x6 walls, foam board under the siding, spray foam or other high density insulations, and careful use of vapor and air barriers to make the house airtight. The cost savings over ICF pay for a lot of upgraded construction techniques to do the frame construction in an energy efficient way.
ICF for basements makes a lot of sense, because you need concrete walls anyway and the ICF is a good way to get there and have an insulated, ready to finish product without the labor of stripping forms. Savings in forming costs partially pay for the ICF material. There is still a substantial labor component to bracing, installing the ICF forms, and removing the bracing. But, the insulation savings offset the costs quite a bit. Use Miradrain or Platen on the outside to make it watertight. No matter what the manufacturers and internet forums say, it is not watertight. Be careful in backfill to not damage it. Spend some time and care in getting it plumb and level, and you will be happy with it.
Overall, ICF is just another technique, like frame, adobe, block, SIP, straw bale, rammed earth, etc. The proponents of each technique (particularly the alternate techniques to frame) are often zealots and push it like it's the answer to everything. It's not, it's an answer, and may or not work in your situation.
Good technique for a house, but get a quote on it compared to frame of equivalent energy efficiency (and other techniques if you like them) and compare what you get for what you pay. Make sure you take into account the increased costs to attach things, do the drywall, side the outside, etc.
Pluses: It is air tight if you do the rest of the detailing right. It is very sound proof. Very energy efficient, partly because of the thermal mass and insulation, but mostly because of the air tight.
Minuses: It is very hard to get it all straight and plumb and level. You'll have to adapt your followup work to that. It is limited in how to attach things; you have to plan ahead. Electric wiring is a challenge, not insurmountable, but you have to plan for it. Siding it is a challenge. Good for stucco finishes, that was my solution both times. Biggest detriment is cost. It is just plain expensive, whether you do it yourself or have it done. If you DIY and don't count your time, the cost deficit is smaller.
I'm building another house now. I didn't even consider ICF. It's cheaper, easier, and you get an equivalent energy efficient product using 2x6 walls, foam board under the siding, spray foam or other high density insulations, and careful use of vapor and air barriers to make the house airtight. The cost savings over ICF pay for a lot of upgraded construction techniques to do the frame construction in an energy efficient way.
ICF for basements makes a lot of sense, because you need concrete walls anyway and the ICF is a good way to get there and have an insulated, ready to finish product without the labor of stripping forms. Savings in forming costs partially pay for the ICF material. There is still a substantial labor component to bracing, installing the ICF forms, and removing the bracing. But, the insulation savings offset the costs quite a bit. Use Miradrain or Platen on the outside to make it watertight. No matter what the manufacturers and internet forums say, it is not watertight. Be careful in backfill to not damage it. Spend some time and care in getting it plumb and level, and you will be happy with it.
Overall, ICF is just another technique, like frame, adobe, block, SIP, straw bale, rammed earth, etc. The proponents of each technique (particularly the alternate techniques to frame) are often zealots and push it like it's the answer to everything. It's not, it's an answer, and may or not work in your situation.
Good technique for a house, but get a quote on it compared to frame of equivalent energy efficiency (and other techniques if you like them) and compare what you get for what you pay. Make sure you take into account the increased costs to attach things, do the drywall, side the outside, etc.
Radix2
Well-known member
My mason used ICF for my foundation walls instead of the block construction typical here - he feels it is a cost savings vs std block or poured ( and insulated).
No basement, so just the 42" frost walls. It went quite fast, and I can see why he likes it. At this height no serious support was needed, but it still took some skill to get the walls nice and straight - mainly some strategic pushing and filling while the cement was still plastic. I went with a lot of under slab and foam all the way down to the bottom of the footers, and am impressed with how well the insulation is working.
No basement, so just the 42" frost walls. It went quite fast, and I can see why he likes it. At this height no serious support was needed, but it still took some skill to get the walls nice and straight - mainly some strategic pushing and filling while the cement was still plastic. I went with a lot of under slab and foam all the way down to the bottom of the footers, and am impressed with how well the insulation is working.
DougWil
Well-known member
I will stand by that, or as mentioned you have a very thick wall.
XPS has an R value of about 4 per in. You would need 5.5" of foam, plus the concrete core usually 5.75" min, plus the interior and exterior finishes, another 1.5".
That is about a 13" wall min. and only R22.
A 13" wood framed wall, double staggered studs etc, would be far more energy efficient.
And you can make a wood framed home very air tight with attention to detail.
R-values are something of a moving target. The “steady state” R-value of a 10-inch-thick wall is between 7.7 and 8.2, according to ORNL tests.
Read more: http://www.greenbuildingadvisor.com/green-basics/insulated-concrete-forms#ixzz4dyAEyuq9
Concrete walls have lots of other positive points like hurricane resistant, basement walls, etc,,, but ICF judged as an insulated assembly isn't very energy efficient per inch.
MushCreek
Well-known member
Since I've never lived in a fully insulated house before, I can't really compare, but our ICF house is incredibly tight, quiet, and comfortable. In our moderate SC climate, it really shines, and we go for long stretches (months) without heat or A/C. We do the whole house with two small mini-splits, and our annual HVAC cost is under $200. That's for the whole year! We used to spend more than that in one month in our old house. The unheated walk-out basement has never dropped below 60 in the winter, or above 76 in the summer. I believe that the 100 tons of concrete in the walls has a significant moderating affect during temperature swings. It's also kind of nice living in a 'bunker' during a tornado warning.
Bear in mind that when I designed our house, I spent a lot of time getting the orientation right to help keep the house warm/cool, depending upon the season, and we used quality windows and R50 insulation in the attic.
Bear in mind that when I designed our house, I spent a lot of time getting the orientation right to help keep the house warm/cool, depending upon the season, and we used quality windows and R50 insulation in the attic.
gnpenning
Well-known member
I think your usage of the term efficient is incorrect. While the R value numbers for a ICF wall would be considered low to a same thickness stick framed. The but efficiency of the ICF is far better. I heat a greater area with more comfort and less money than the same in stick frame.
Having helped build some ICF homes and stem walls for others when it came time for mine I tried ICF. The quote I received for my basement walls using regular cement walls was higher than what I paid for all the block, bar, and mud for my basement and main floor for my home. No labor just materials. I didn't have any issue with different block sizes or some of the other problems other have mentioned. The dealer for my block (Amvic) rented out the bracing. My block walls are the straightest walls I have. The time saved mot needing to checking all the 2x material for straightness was worth it alone.
My garage has some 2x6 walls. I was **** about caulking all the seams and foaming any penetrations, including wiring holes and the back of all electrical boxes. A outside wrap and inside vapor barrier was used. I did the electrical in February both in the house and in the garage. No air movement was found with the block (no surprise) but in the garage air movement was found in many places. Something I went out of my way to stop.
I have radiant heat. Based on the the control panel the garage zone stays on far longer than the other 3 in the house. I would say the ICF is more efficient than stick framing. The comfort level with ICF is amazing. Having come off the coldest winter we have had in many years My heating bill for the past year is less than $500. That is heating over 4500 sq ft. Including a inefficient garage.
Wind shear is the biggest heat loss and gain in a home. That is the air transfer thru the walls, door, and windows. Thermo imagining of stick framing vs ICF will back this up. ICF has no air movement making the wall more efficient. Insulating verse's stopping hot and cold transfer are 2 different things. With ICF your doors and windows are you biggest heat transfer areas.
One thing not mentioned with ICF is the lack of areas for Mice and bugs to move thru the walls. Or places for them to enter the home. Living in a rural are this is nice.
I just talked to 2 of my neighbors tonight and both complained about the noise of the increased traffic has brought. I don't hear any of it unless outside. You can't hear the snowplow going down the street.
Having lived in stick framed and the last 7 years in ICF. My next home will be ICF. My last stick home I did radiant as well and had 2x8 walls with less sq ft. The ICF has been cheaper to heat with a greater comfort level. I've had both and paid the bills for both. I may not be able to boast a high R value, but my comfort and heating bills are less. ICF all the way for me.
MushCreek
Well-known member
I looked at a lot of different building methods, but one of the main reasons I went ICF is because I'm one old man, working alone. I have no way of raising framed walls, or SIP's, which was another method I considered. There are a number of ways to build a tight, well-insulated home, and no one 'right' way.
wssix99
Well-known member
I didn't have any trouble getting the permit because my wife has built over 20 ICF houses in the City.
Other contractors would not have the same experience... Biltmore Homes is the only mason that I know of (they worked with us) that has recent ICF experience in the City and is still operating. http://www.biltmoreicf.com/ They also have contacts to competent architects and others who can get things permitted, approved, materials reliably delivered, etc. in the City.
I will echo ssdave's comments. Having an experienced mason to deal with the complications is critical - particularly in the City where things are vertical and the stakes are raised 10 fold. (A blow-out at height is a hell of a lot different than a blow-out at ground level!)
Building a full structure ICF house in an urban environment is a long-term investment. There is no way to avoid being underwater the minute construction is done. If you are going to sell in the next 10 years, you should pick another construction method because you'll never get your money back out of it.
In our situation, we've built our long-term house and wanted something that will perform well when we are living on a fixed income. The ICF is also a luxury and this is the most comfortable structure I've ever lived in. The mass walls perform in amazing ways (thermal, sound, wind, etc.) and there's no substitute for them.
wssix99
Well-known member
I see your mathematical statement about efficiency “per inch”, but I’m not sure that’s a very meaningful measure. It might be in a very constrained urban situation – ICF construction would loose a foot of usable width on a small lot. In our City, a standard lot is 25’ wide and then we count down from there based on the wall assembly and any other needed set-backs.
My wife has built uber-efficient houses (with thick wooden walls) here in the City in addition to the ICF and the air sealing just doesn’t happen. The nature of the contracting business is such that someone will always cut the important air sealing “corners” when the boss isn’t looking.
To your other point, the guaranteed air sealing and other benefits of the mass walls are the reason to do ICF. (In an urban environment, some people also choose it for its resistance to “lead projectiles”.)
Air sealing has some major downsides, which require high-end mechanical skills. For example, negative pressure is a major demon which we have been chasing since construction, but that’s a topic for other threads…
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DougWil
Well-known member
Do you know how contradictory that statement is?
R value is a measure of thermal resistance.
Are you comparing a new ICF home to some old, leaky, poorly insulated, low quality windows and doors and poorly constructed wood frame? If so it isn't a surprise that ICF is more comfortable.
Almost all the super energy efficient homes are wood framed, you simply can not get as energy efficient a building from ICF w/o very thick walls, and much higher construction costs.
5.75 inches (the concrete) of an ICF wall has basically zero R value.
Plus the 1.5 inches of stucco and plaster, which also are basically zero.
That is 7 plus inches of the wall with no thermal resistance.
What on a wood framed wall has zero R value? Nothing, maybe the stucco if it uses stucco.
Well measured by the inch, ICF isn't very energy efficient.
Measured by initial construction cost, ICF isn't very energy efficient either.
So by what standard do you want to measure energy efficiency?
And because of the wall thickness and weight you can't use std door frames, windows are deep set and a larger footing is required, all adding to the cost.
Air sealing can be done on wood frame, it isn't that hard and it can be done to where the house is too air tight and fresh air must be brought in.
Crappy workmanship is always an issue, poorly installed batt insulation drops the R value substantially. Many homes have R19 in the walls but because of poor installation the overall effective wall is R9.
Does that mean you shouldn't use batt insulation?
ICF can have other "values" as mentioned, but being energy efficient isn't one of them.
Really if you want a concrete walled home, the concrete should be precast where the wall design is much more efficient because of the plant controlled conditions, as in a thinner wall. And the hard, durable concrete should be on the outside protecting the soft, flammable, low melting temp foam from the elements, fire, woodpeckers etc...
Putting stucco over exterior foam just creates a soft base where the stucco can be easily damaged, especially the soft stucco used these days.
I have seen lots of thin EIFS where you literally can poke a hole through the finish with your finger.
Firebrick43
Well-known member
You keep quoting R value but even that is a skewed test that artificially boost the on paper performance of fiberglass. The test is set at 70 degrees and a heat source is added to on side and it's timed how long the other side takes to raise a degree or two.
However fiberglass as the temp differential gets extreme(70 inside and 0 degrees out side for example) their will start a convection currents form and the actual performance pluments.
Also sheathing the exterior in foam with a wood wall and a insulation that can be saturated is a recipie for disaster. To get the air sealing you have to use a plastic vapor barrier on the inside creating a double vapor barrier. I have seen several high efficient houses with rotting walls due to this. For evidence reasearch EIFS lawsuits and the massive problem they are presenting accross the country. They were the first to apply foam continuous around the outside. as water proof as the EIFS is, no matter how well one flashes and seals Windows and doors, with wind driven water some will infiltrate especially as time goes on and seals compress and caulk fails. Even tyvek fails with age as the pores get filled with dirt. Look up tyvek failures.
However a little moisture, even if it can make it past the foam, gets into the concrete core, meh! No issue. No degredation of performance, no super costly remediation.
DougWil
Well-known member
True and R value isn't a constant and varies by temp.
http://www.energyvanguard.com/blog/59419/Big-News-The-R-Value-of-Insulation-Is-Not-a-Constant
But fiberglass can perform very well if installed correctly and with an air barrier.
rburke65
Well-known member
Wow.... It would seem to me that science and data would have been able to figure out a true R between ICFs and a 2x4" by now!
gnpenning
Well-known member
Doug it is clear you have no use for ICF and that is fine with me. What you are using as examples don't equate. Efficiency has to be looked at as a package not just rated R value. They way you look at it my statement it may be contradictory to you, in reality it's not. R value and efficiency are not mutual exclusive. Just because you have a lot of insulation doesn't make it efficient.
For those looking at ICF, I do not have one custom ordered door or window in my place. Extending door jambs is simple and can be done on the job. The windows you just use wider material when you box.
Again the comfort, sound blocking, lack of air filtration, rodent and bug reduction, and many other benefits make ICF a great choice for the DIY or professional builder.
On any of the ICF's I've been involved in we haven't had a blow out. It can and does happen. Great care in the prep and and pour pay off. When you vibrate the walls, if you try and do it the same as other formed walls you will have problems.
Again my cost was cheaper than having someone else come in and pour my foundation walls. Different parts of the country will have different pricing. We have 2 very good ICF dealers in the area which makes pricing competitive. I've worked with both and you can't go wrong with either one. I realize not everyone has that option. Please feel free to ask questions.
For those looking at ICF, I do not have one custom ordered door or window in my place. Extending door jambs is simple and can be done on the job. The windows you just use wider material when you box.
Again the comfort, sound blocking, lack of air filtration, rodent and bug reduction, and many other benefits make ICF a great choice for the DIY or professional builder.
On any of the ICF's I've been involved in we haven't had a blow out. It can and does happen. Great care in the prep and and pour pay off. When you vibrate the walls, if you try and do it the same as other formed walls you will have problems.
Again my cost was cheaper than having someone else come in and pour my foundation walls. Different parts of the country will have different pricing. We have 2 very good ICF dealers in the area which makes pricing competitive. I've worked with both and you can't go wrong with either one. I realize not everyone has that option. Please feel free to ask questions.
The material R values are all well characterized, but it is complicated by many factors several of which are conflated (knowingly and unknowingly) in this discussion. All of these other factors affect perceived comfort, HVAC energy, etc. Fun isn't it?!
Materials have R-values that depend on temperature, humidity, time, production quality, etc. Wall assemblies have "effective R values" that change according to construction method, quality, bridging, mass, etc. Buildings have effective R values that depend on all the sub components and their construction.
On top of that, the leakiness of the envelope is a way for the weather to bypass any R value and the mass of material inside the envelope also can act to effectively displace any R value by moderating the change outside.
So you have all these factors that make a direct comparison fairly difficult and probably ensures that there are scenarios where everyone is right.
My 2 cents
1. Per inch, advanced stick frames will have higher effective R values compared to ICF because there is more insulation.
2. ICF are easier to get air-tight, but many contractors have no problem making exceptionally tight stick frame buildings.
3. There are tons of ways to lower construction costs on all types of construction and variations in materials, labor, efficiency, etc by crew, region, design, etc that make general economic comparisons very difficult.
4. In an imaginary scenario where stick and ICF buildings have the same R value and same air tightness, they would yield comparable thermal comfort, and the total energy use would probably be less with ICF, but it depends on climate and the ability to leverage the thermal mass of the ICF. A poor implementation could decrease comfort.
5. In a comparison based on wall thickness, ICF would have a lower R value and then a comfort and energy savings comparison would come down to R-value vs mass, which depends on climate, windows, orientation, even things like interior surface finish. It is possible for ICF to save at lower R value because in most climates much of the load swings though the balance point.
Stuart in MN
Well-known member
Since a newbie bumped an old thread with a new question but no one noticed, I'll re-post his question again so it doesn't get buried in an argument.