ICF Walls of Various heights. How to?
Designing an ICF house for a future DIY project. Going prairie style and it’s important to my aesthetic that I have variable roof and wall heights. However, I am not sure how to go about constructing the exterior walls above the lower roof lines. If you can’t tell from the attached screenshots. There are a couple shared “interior” walls but the rooms will have different ceiling heights and all 3 in the picture are different roof heights. In the white image I labeled the exterior height of those walls and one of the openings (22ft)
The exposed external wall above the rooflines baffles me about constructing with ICF. Only options I can think of is running internal ICF walls to carry the load of those taller walls. (Money and space consumer). Another option is to stick build those shared walls and insulate the hell out of them internally and externally to get the air tight / thermal envelope to match the ICF walls. Or… something crazy like build the internal walls and come back and try and build ICF on top of them after the initial wall pours?
I would prefer to stay ICF. I don’t want internal columns and header to support the taller wall sections of ICF. I know if I stick built I’d have some header assembly anyway… but ideally none.
These shared internal areas aren’t always going to have a wall below them, some will have large openings to other rooms (12 foot+) I know I will need headers in those cases.
Am I missing some cool technique with ICF I don’t know about? I cant seem to find good research on how far you can span an ICF “header” without additional support.
What are my real options?
Thanks.
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Replies
bpemberton,
I'm a bit too distracted by your first image to answer the question.
Hipped roofs that terminate in a dead valley against walls are a disaster waiting to happen. There is simply no good way to detail them so that they aren't risky.
In a heartbeat I would stick-build it. Everything above the foundation. Specifically, I'd work with an engineered lumber designer to get engineered lumber for those big spans.
For the same r-value a framed wall is going to be 8 inches thinner than an ICF wall. You can make a framed wall just as air-tight. Every detail along the way, from installing windows and siding to plumbing, electrical and drywall, is going to be easier and cheaper with framed walls.
Lot of these house styles come about how people slowly expanded their home over time. It made a lot of sense to build that way in stages slowly over time but makes zero sense for a new build.
There are many other ways to add visual interest to your house that doesn't involve all these wall/ceiling/roof intersections. You'll also find they are much easier to build and way easy to detail air tight.
Yea, sorry the hip roof detail isn't complete. I used an extension that threw in hip roof automatically and It doesn't know I am terminating against a wall, ignore that. I will fix when I start to fine tune my plans.
I know very well I can get same and better R value and air tightness with stick built construction. It's not my only concern. With out a long drawn out explanation, just know I am going ICF construction without a doubt. If I have to stick build in certain spots I will to achieve the look I am after.
I didn't come here for opinions on my houses aesthetic design choice. Unless you're paying for it or living there, I don't really see the point in critiquing it.
I like prairie style and I like multiple roof lines. It's a 17,000 square foot house. It's a sprawling single story with court yards and the such. I'll give it character the way I want. I have designed and GC'd the last 2 homes I have lived in. I enjoy the whole process and educating myself on building science over the last 20 years. For some reason I fell in love with building science late. Kinda wish I took it on in some form as a career. Although I'd probably not be able to build this house if I did. This will be the first house I do a the majority of the work from the ground up instead of hiring a ton of subs.
I've been snooping on these forums for a looong time and a lot of you have been very helpful in my education process.
So thanks for that.
bpemberton,
Ah good! Those roofs worried me. I don't see why a hybrid system of ICFs and stick framing wouldn't work - and it's in some ways in keeping with the prairie style aesthetic, which often featured load-bearing masonry or stone walls interspersed with wood framing. When deciding which walls will be of which material I would play off that so you don't just choose based on ease of construction but also aesthetics.
"With out a long drawn out explanation, just know I am going ICF construction without a doubt. "
Well, this site is Green Building Advisor. Since there's nothing green about putting unnecessary concrete into a building -- it's one of the most environmentally destructive materials used in construction -- I'm not sure how much help we can be.
Oh interesting, I'll bite. I wonder how much research you've personally put into this. I wonder if this isn't just a common statistic that was once thrown out into the culture and then repeated by the masses.
I'd love to see some raw unmolested, non-politicized, non-agenda affirming data about a statistic such as this. I am not at all saying your statement is wrong. It may very well be "one of the most environmentally destructive materials". I always take a step back when broad and damning statements are made, about anything. I wonder how truly bad concrete is in comparison to other building materials. I wonder what criteria are used to determine "environmental damage".
Is it that, oh so politicized, "carbon footprint" we hear so much about? Our supposed impact on global warming? I wonder if you tally up the materials, and all the carbon used to produce those materials, to construct a concrete building or wood building of equal energy efficiency over the entire life of the building. Also comparing the life expectancy of said building. Does a stick built building of today last 100 years? With today's quality of wood and wood products? Do all these fancy claddings, membranes, tapes, liquid applied products, insulation, fasteners, glues, etc.. hold up for 100 years? How much potential efficiency will a house lose over that 100 years due to a degradation of any of the aforementioned materials? How much carbon is consumed in manufacturing and allocating these materials we use for construction to achieve our "green" homes?
How does that compare to a concrete home, which will inevitably share many of those materials, however mostly on the internal structure where degradation may not effect energy efficiency as much. Is energy efficiency even the right metric to calculate? It seems like a good one. The amount of money spent, oil/gas burned, electricity used (often just more oil or gas burned in most areas) to keep your house in a habitable state throughout it's entire lifespan. That would involve upkeep and repairs too. Any repair/ replacement you make is just more energy used to service that home.
Anyway, like I said previously. You could very well be right. I just like to give a little nuance to most things. You'd have to really sit down and calculate every aspect of building construction and it's energy used throughout the lifespan. I wonder how close efficiencies really are if you get into the nitty gritty.
"Our supposed impact on global warming?"
Do you not believe in climate science? If this is the case there is not really anything to say. If not, then simply google environmental impact of concrete, there are countless journal articles, studies, and high quality sources like MIT that can explain why concrete is so bad for the environment.
I would argue that a modern stick frame house will actually age better than an icf house as updating and modernizing it will be much easier. And there is nothing about modern lumber that will make it magically degrade in 50 years. If it is structurally sound now, there is no reason it can't remain that way for hundreds of years. All houses will require maintenance, your icf one not withstanding.
"What are my real options?"
Hire a designer or engineer.
"Do you not believe in climate science? If this is the case there is not really anything to say. "
I believe in climate, I believe in science. When you put those two words together it now depends on what version of climate science are you referring to?
Do I think we are dooming ourselves with too many cow farts and we need to all go vegan or invest in lab grown meat to save our planet? Nope.
Do I think we are the primary cause of the change in weather patterns global temperatures? No
Do I think we might effect weather patterns and temperatures? Yes.
However, now it gets a lot more nuanced... at what metric of measurement do we want to use?
I think our large concrete cities effect local temperature and weather patterns on a micro-scale, in individual micro-climates. On a global, long term scale, not as much. I think its important to zoom out and take a large, long perspective on temperature patterns throughout the history of this planet. The planet has patterns of heating and cooling cycles on a grand scale. Long before we came around with our nasty emissions of green house gases. Science shows us this with core samples in the ice and rock.
Do I think our future generations have much more important things to worry about? Yes, absolutely
Do I think we better start worrying about our agriculture and food supply now, in a very serious way so future generations have food? Do I think mono-crop agriculture is unsustainable and our top soil is hanging on by a thread? Yep.
Do I think we are polluting our air, water, and food with toxins and harming generations of people? Yes, without a doubt and its disgusting.
I think the vast majority of climate science is propaganda for various forms of agenda. I think it's important to do a lot of research and find truly credible resources from many sources and then extrapolate your opinion from there.
I think it's ill advised to accept the opinions of a handful of "experts" on any given subject. If this recent expertise on this fun pandemic we all went through wasn't a great example of that, I don't know what is. The problem I find is almost every study has a bias. Almost every study is funded to support one side or another, for whatever agenda they are after. Critical thinking and long grueling research is the only way to find out what is fact or, one of those fun new buzzwords, misinformation/disinformation.
The problem is the vast majority of people don't have time or any interest to do any bit of self research on any given subject. It's much easier to listen to what your TV or Social media tells you and then regurgitate that information to your friends at the bar or in the breakroom at work. Most people have no idea how truly disgusting and selfish industries and corporations can be and how influential they can be on our "science". It's a lot easier to live a naive life and just be a cog in the machine, doing what your told.
Rant over. Otherwise I could be here all night spewing more of my nonsense into the ether.
For the most part, buildings don't get torn down because they wear out or become structurally unsound. They get torn down because they're functionally obsolete. In any major American city post-WWII skyscrapers are being torn down all the time because it's more economical than retrofitting them as modern buildings, they're still quite structurally sound.
Wood buildings last essentially forever, the oldest house in my home town was built in the 1630's, of wood. If they don't last forever it's because they don't get maintenance, and usually the reason they don't get maintenance is that they're no longer useful. The key to a long-lasting building is not to make it out of indestructible materials, but rather to have a design that can be adapted as needs change.
Yep I live in Chicago, well suburbs now. I've seen it many times. I also see a lot of retrofit cladding on these buildings for better efficiency. Some of these successful, some a giant waste of money and resources. I can't imagine the cost financially, and energy consumption to heat and cool these giant structures that were built 50-200 years ago. Many of them are almost entirely encompassed in glass, or old brick with little to no exterior or interior sealing or insulation.
When talking about a personal dwelling however, not much has changed as how we use our buildings. Eat, sleep, protection... The maintenance comes at a cost. I venture to guess maintenance on that 1630s wooden structure is quite cumbersome, if its not already been completely rebuilt over time and not just claiming 1630s house by location and footprint. I'd like to see a 1630s original house that isn't leaking energy like a sieve.
Every building will require maintenance, no doubt. I feel the most building adaptation mainly occurs in building science for the purpose of building to last and to maintain efficiency. The biggest structural change I see in modern homes is just much less internal walls. Gone are the days of formal dining rooms, libraries/studies, etc...a wall to divide every activity in the dwelling just isn't as favorable as it once was.
I don't disagree with your philosophy that a building should be adaptable. I simply wonder how accurate it is to say concrete is one of the most environmentally destructive materials. I wonder what metrics and agendas are at play to make such a statement. I've read plenty throughout the years and seen many videos about manufacturing of various materials and I just don't think its so black and white if I put my critical thinking cap on.
"How does that compare to a concrete home, which will inevitably share many of those materials, however mostly on the internal structure where degradation may not effect energy efficiency as much."
So you lost me here. ICF usually means two layers of foam with concrete in between. The exterior foam is exposed to the weather and still needs cladding to protect it, the windows and doors still need to be flashed and taped to keep water out.
Yea, hence me saying it will share many of the materials. The bones will stay the same though and there is much less material to keep those bones healthy. Again, I am not saying you are wrong, lol. I just wonder how right you are.
From a cost perspective the framing is like 10% of the house.
Would it not work to just use a 10" core until you reach the height of the first wall than switch to a 6" core? to go to the higher wall?
Not really but I like that Idea for some other things in my project.
In this case these are interior walls below the roof line. That mean's I would have to run interior ICF walls in quite a few areas. I am not totally against it. I already have some large interior walls of ICF for the theatre room. In this case with these varying height walls I am likely going to have to stick build those sections due to what I plan for on the interior where an ICF interior wall just wont work like I want.
I was hoping I was missing something obvious that someone could point out, because ideally I'd love the entire shell to be ICF but I also don't want to sacrifice my aesthetics to try and achieve that.
I am assuming your problem with this solution is that you do not like the idea of a solid 10" concrete wall with 5 more inches of foam in the middle of the room? Your original comment about stick framing and coming back with ICF above that could be modified to use steel and not stick framing I would think. Would need an engineer but I would assume it would be possible to have a steel beam for a header at whatever height you want to support the concrete wall above. If the steel cant span the far put steel columns under it and those are much easier to hide on the inside than a 10" concrete wall. I would also assume it would be possible to have the steel in place supported by temporary stick framed walls so you can pour the ICF all at one time.