Why haven’t steel-framed homes become more popular?
I am in the planning phase of building a home in the NJ-NY area, Climate zone 5. As I investigate my options; SIPS, double wall stick 2×4 wood, 2×6 wood, ICFs, CMU, Larsen trusses, etc.. and the myriad of permutations to insulate each one (spray foam, cellulose, hybrid batt & flash, exterior rigid foam/iso panels, etc….) I came across STEEL. My goal is as high R-value as I can get within reason $$, with hope of upwards of R-30 final values. That said, I need some objective input.
Steel seems like a really good option. Almost unheard in my area, despite being upwards of 60% recycled, lasts forever (relatively speaking) super strong, straight, minimal waste, not affected by termites/pests or mold, equal or close to wood in cost (depending who you ask). I know it has very high thermal conductivity. However there are configurations that can abate this significantly (braced walls with double layer of external 2″ poly-iso taped & staggered seams as sheathing, +/- flash SPF to give the wall more rigidity tieing it all together). Why isn’t it more popular? Am I missing something? Thank you kindly for any thoughful input.
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Sal,
Any insulation you install between the studs is basically worthless, because of the thermal bridging through the studs -- so you have to put all of your insulation on the exterior side of the wall.
You're right that it's possible to install two layers of 2-inch polyiso, giving you R-26. That's OK, but it's not great.
If you can find a way to add more exterior insulation -- say, 6 inches of polyiso -- you can end up with a pretty decent wall. Just remember to keep all of your insulation on the exterior side of your wall framing.
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Martin, can you explain this comment in a little more detail: "Any insulation you install between the studs is basically worthless, because of the thermal bridging through the studs"? Obviously the thermal transmission of steel is much higher than that of wood but the effective CSA of the steel stud is far smaller and the proportion of insulation to structure in a steel stud wall can be much higher, especially at headers. Most sources I have seen on line suggest an overall hit of about R2 on the assembly compared to wood framing, but one technical paper corroborated your perspective without explanation. What gives? I would certainly agree that continuous external insulation is a must with steel framing as I've seen the pattern staining that can result without it, but NO value to the stud cavity insulation?
To Sal: my brother has just moved into a new steel-stud framed home in Australia where it is pretty much the standard choice because of its termite resistance and low cost in a country where native-grown framing lumber is much scarcer than in the US. They also have a tradition of prefab steel-framed bungalows and light commercial structures dating back to the Victorian period. I suspect it's a combination of cost, availability and familiarity which keeps US residential framers working with wood. Steel framing is common in commercial construction in the US where it's a code requirement in most downtown fire districts so I assume the skills are available. Obviously standard 14.5" batts would not be suitable.
James,
Full disclosure: the phrase I chose -- "basically worthless" -- was an exaggeration.
I'll quote Joe Lstiburek: "Put an R-19 batt in a steel stud wall and you are lucky to get R-5 to R-6 in the real world. That’s equal thermal resistance wise to about 1 inch of rigid insulation installed on the outside of the steel studs."
More information can be found here: A Bridge Too Far.
Uncle Joe is always an entertaining read - "You want romance? Get flowers and Viagra. Both are much less trouble than a fireplace and much more reliable" - but being in a questioning frame of mind I'd still like to see some empirical quantitative data on the heat transfer through steel studs. Exactly how do we arrive at the R5 or R6 'real world' number? Joe shows extreme examples in commercial multi-story construction to make his point: heavy structural steel sections, exposed concrete floor slabs etc. etc. but this is a poor analogy for the condition of a carefully-framed single family home.
And on the theory side, Joe's sardonic comment on the heat-transfer efficiency of the 'radiator fins' at both sides of the stud notwithstanding, the web that connects these fins is only around 0.02" thick. Just as the steel standoffs Joe finds acceptable for supporting exterior brick angles limit but do not eliminate the thermal bridge by their (relatively) small cross-sectional area, doesn't the extreme thinness of the web severely limit heat transfer through a structure, especially one which is already protected by continuous exterior insulation? Compared to the heat loss through even a good quality window I can only think the quantities involved are minute, hardly enough to anesthetize the effect of properly installed cavity insulation. Not particularly trying to make a case for steel studs here, just finding the 'don't bother to insulate the cavity' arguments difficult to follow without actual data in evidence.
A further thought from a structural engineering perspective. In Joe's apartment building example (Figure 5), for every additional inch of external insulation the thicker and heavier the standoffs must be which support the brick veneer. That old moment arm thing. Those guys are already pretty substantial, with chunky heat transfer plates bolted to the slab edge. So omitting cavity insulation in this case to compensate with additional thickness on the exterior is not without energy cost and may simply be trading one thermal bridge for another.
James,
More sources of information:
GBA Encyclopedia: Steel Studs: "The California Energy Commission claims that a steel stud conducts 10 times as much heat as a wood 2x. This thermal bridging drastically lowers the performance of insulation in wall cavities. A study by the Oak Ridge National Laboratory (ORNL) found that thermal bridging in a conventionally framed wood wall lowers the performance of cavity insulation by 10%; in a steel-frame wall, performance drops by up to 55%."
Below is a table from Environmental Building News (http://www.buildinggreen.com/auth/article.cfm/1994/7/1/Steel-or-Wood-Framing-Which-Way-Should-We-Go/), with values based on ASHRAE 90.1.
.
Thanks for the input. James I agree much of what we do as human beings results from familiarity. We do things cuz thats the way its been done. Not being a seasoned builder I came to the "problem" with an open mind, how do we frame this structure and what are my options? Thats why I even considered steel. I will post true costs as I get numbers, that may ultimately be the issue.
I was aware of Lstiburek's comments and from thermal bridging concepts it seems obvious the money and effort is better spent to "outsulate" the wall. Martin point's out despite an R-19 batt, with the thermal bridging it's essentially useless (R-5 +/-). Funny thing is one of the steel suppliers is quoting outrageous R-value potential, not even suggesting outer rigid insulation, with not one comment about the thermal bridging issue. I didn't challenge him, given enough rope, he's already hung himself. CAVEAT EMPTOR
Late to the discussion, but here is a link to the ORNL page covering steel framing with and without the benefit of "outsulation":
http://www.ornl.gov/sci/roofs+walls/AWT/HotboxTest/LennarSteel/results.htm
There are new wall calculators available at the same site.
FWIW, here is a thought for a rather simple r 30+ wall. basically a 2x6 "Mooney" wall.
Siding, 3/4" furring rain screen gap, permeable WRB, 3/4" fiberboard, 2x6 24" OVE cavities filled with r 23 Roxul,1/2" plywood sealed as air barrier, 2x4 horizontal strapping 24" OC screwed to studs creating a 3 1/2" cavity that's filled with r15 Roxul, drywall.
Jerry, I think before I did a "Mooney wall" I'd consider a double 2x4 wall with a cavity. Goes back to familiarity (for better or worse). Issue with those type of wide walls, is I am not willing to give up that much square footage. I did my best to keep the rooms to a good size, but not too small, to avoid the crippling taxes we "enjoy" in this part of the N. East. Steel offers many benefits, the downsides, mainly thermal conductivity, can be corrected for with double layer taped and staggered rigid panel outsulation. Issue that arises next, as James above mentioned, is as you "push" your final wall layer - the siding - out further from the structural wall, you need to compensate. Since we're looking at a combo of stucco (or EIFS), brick and real stone veneer, an attachment system and ledge needs to be designed into the wall (a very wide brick ledge bumping out from the upper foundation wall?) to bear the weight of the siding now about 5 inches away from the steel members. Plus a substantial anchoring system that ties back into the steel members, there is the issue of thermal conductivity again?? in this system with braced walls, do I need structural sheathing?
What about this kind of steel framing :
http://blueskybuildingsystems.com/
I enjoyed looking through their website.
I am also curious as to why steel hasn't caught up a little more attention in residential framing in canada and usa ...
I tend to like concrete because of it's long term life, steel and aluminium are also materials i favor because of the same factor.
Steel is sooooo cheap VS weight/strength ratio
What do you guys think about their exterior foam with embedded steel strips ??
Anyhow, i'd like to see how a frame from their system costs installed VS quality wood framing.
Also, why are we still talking about in frame insulation for new buidlings?
I thought that PERSIST type of construction was determined to be the best contruction method for insulation and condensation ?? :)
why settle or something less ...
Not to do the steel-frame thing to death, and continuing to stray from Sal's immediate concerns, here's another ORNL link:
http://www.ornl.gov/sci/roofs+walls/research/detailed_papers/steel_frame/index.html.
After testing a variety of stud assemblies it paints a more complex picture than the California Energy Commission's summary would suggest. I could find no suggestion that the tests support omitting cavity insulation, and the tests show a pretty good R20 wall with just 2" of continuous outside insulation. If you're headed for R30 and beyond though I can see why piling foam board insulation on the outside of the wall would ultimately lead to a strategy of leaving the cavity empty - why bother with filling a perfectly good service cavity with fiber to get a measly R9 or so when you can get the same results by adding another inch or so of polyiso on the outside. But this strategy would apply to a wood framed wall equally well once you transition from seeing external insulation as thermal bridge and condensation protection to seeing it as the complete insulation package. Dr. Joe has clearly made that shift in his thinking. I guess not all of us are there yet, especially those in milder climate zones.
The study also mentions advanced steel stud technologies which while they certainly have cost implications do suggest the potential for a thermally efficient structural alternative to wood framing if that's your focus. I see no consideration though of an offset double stud wall to address the thermal bridge problem. But if you head in that direction with steel stud I don't know how you'd attach the scrim for dense cellulose fill. Spray fiber might work.
One further thought on steel vs. wood framing that probably should be mentioned in a green building context: the US construction lumber industry sequesters many thousands of tons of atmospheric carbon every year. The steel industry, despite green claims for the recyclability of the product, not so much.
Great reference James, thanks. Interestingly I was considering the a DIY version of the "stud snuggler" before I saw it.
http://www.ornl.gov/sci/roofs+walls/AWT/NovelTechnologies/studsnuggler.htm
Rip 2 inch strips of a high compression foam (1 or 1.5 inch?), and line the interior side of the steel frame member (attach with builder's glue). Then apply the sheetrock. Thus isolating the steel member both on the interior and exterior side. Based on http://www.ornl.gov/sci/buildings/2012/B11%20papers/196_Kosny.pdf
Application of stud snuggler resulted in a 73% improvement in thermal performance as tested in a 2x4 wall. I am impressed. What about doing a stud snuggler with only 2 in of exterior rigid poly-iso and fill the cavity with fiberglass batts vs cellulose?
Sal: fiberglass batts are not the best choice, if you do go in that direction a standard 14.5" batt designed for wood studs will not fit correctly. The batt has to be the full width of the stud o/c and must fit into the web of the stud which is not so easy to achieve consistently. As I mentioned previously attaching the scrim for blown-in dense pack cellulose may also be problematic, this is usually stapled to the side of the stud. Your insulator may have a way to do this though. Sprayed-in fiberglass such as JM Spider may be a better option. IMHO the stud snuggler strategy is probably not worth the trouble if you have 2" or more of foam on the outside as your thermal break, Martin and others may disagree.
James Morgan: delaying is not solving ... stop thinking in human life time
wood house are eventually going to get demolished and burned up or rotting ..and we are talking 100-200years maximum ..not 1 billion :p
Jin: your post is kinda cryptic but if you're referring to my carbon sequestration comment, at this stage in the carbon crisis five or six human generations would seem like a good start. But I'm sure you have many better suggestions.
Hi Sal: keep in mind that you can also choose to frame the exterior walls with a high R-value method such as double stud, SIPs, etc. and alternatively frame the interior walls with steel studs.
Sal:
Here's a suggestion for a relatively simple assembly which would get you to a thermally broken R30+ steel-frame while keeping your foam use to a minimum. I still think that in the N. American context steel studs are a solution in search of a problem but if you're set on it this would probably be a good way to go:
6" steel stud with JM Spider blown-in fiberglass or DP cellulose;
1/2" sheathing, 1" or 2" exterior foam & rainscreen siding: GBA has guidance on the thickness needed to prevent condensation at the sheathing in your climate zone.
2x horizontal wood strapping on the interior to complete the thermal break and provide service cavity.
http://www.specjm.com/products/sprayin2/spider.asp
I don't know the relative installation costs of the Spider but GBA Advisor Michael Chandler has been a big fan. I doubt it would cost near as much as 6" of external foam plus the more complex detailing that would entail. If you went for dense pack cellulose the retaining scrim would be held in place by the wood strapping. I'd still stay away from batt insulation of any kind for reasons before mentioned, nor would I use spray foam anywhere in the assembly. AWB at the exterior foam layer.
Thanks Jan, a hybrid wall with an exterior isolating layer sounds interesting. However, one of the very attractive features of using steel is the elimination of materials that can contribute to wall failure - OSB turning to oatmeal, glue failure, wood feeding mold. Poly-iso exterior sheathing and steel stud members has removed any "mold food" from the wall. Decay organisms have nothing to decay in this design. No moisture reservoirs to suck in water, except the exterior stucco, which is just that, exterior. Also removes reliance on adhesives and need for a crane and leaves you with a "relatively" noncombustible wall. Thats what I am baffled, with such features, why hasn't it caught on more. Its achilles heel of thermal conductance can be been addressed rather effectively, yet no significant in-roads in residential construction. I understand those building for spec could care less, as long as they fulfill the bare minimum of the building code, but a thoughtful design might incorporate steel, I would think? Yet practically unheard of beyond ORNL research papers. I am working on numbers, will post comparison tables. The cost may be the issue, yet I am assured it similar if not better than wood.
A distant second-best to blown fiber, there are rock wool & fiberglass soundproofing & fireproofing batts available cut in widths designed for steel stud framing at standard stud spacings, but it doesn't solve the severe thermal bridging issue of the steel itself.
In residential apps I've only used steel studs for things like partition walls in basement with intermittent minor flooding issues, or for tying into masonry chimneys where meeting code for distance from the interior of the flue or firebox to combustibles could not be met using wood framing. Steel framing isn't very expensive, and can yield VERY straight/flat walls relative to milled timber framing (but not dramatically different from finger-jointed studs.)
There really isn't a good way around the high thermal conductivity of steel though- even at 24" o.c. framing the whole-wall R values will always come in at about half the center-cavity R, whereas with wood studs and R3.2-R4/inch cavity fill the whole wall values come in at something on the order of 75% of the center-cavity value even at 16" o.c. spacing.
While stud-snuggler (which I've never seen commercially implemented ) or aerogel stud-edge strips (which ARE commercially available- see: http://www.thermablok.com/ ) mitigate the conductivity issues, it's no cheap panacea.
Sal,
Regarding issues of moisture damaged materials and mold...
These really shouldn't be issues for enclosures using materials other than steel either.
The success of any design whether using steel or not is going to depend on how thoughtful the designer was.
James Morgan: sorry for the misunder, my lack of proper english makes it hard to convey the correct emotion/direction in texts ..
but on the same direction, just how much "mass" represents all human habitats on the planet ?
how much carbon are you going to plant there temporarily .. we are mere sand grains vs the mass of the planet, and the quantity of things we can move is reflected into this ..
i'd prefer building a concrete or steel house that will outlast by 2-4 a stick framed house
and give some time to trees to grow real size
( here in quebec, all u can find is young trees..everything been cut down in the last 100 years ...
and this is very damaging to ecosystem.. )
anyhow, i think we ( canada + usa ) been using alot of wood in buildings for quite some time,
how many % of the available forest trees have we used in the 2 countries ?
going from petrol to electrical ( or hydrogen or whatever else ) to move around and produce electricity, will have a million times larger impact on the carbon status of the planet
my 2 cents ..but i might be completely wrong on most of this stuff ..just my current line of thinking
Sal, I've just been reading a fascinating New Yorker article on pickpocketing, conjuring and sleight-of-hand which refers to "so-called “inattentional blindness,” the phenomenon of focusing so intently on a single task that one fails to notice things in plain sight." GBA has a wealth of information 'in plain sight' on how to avoid your concerns about moisture damage to a building structure. Most of them naturally enough focus on keeping the water out of the structure in the first place - for most common purposes it's better to invest in a tight, stable ship than a high-power bilge pump or a design that will still float though its occupants may be swamped and miserable. Pay attention to these guidelines and you will have a low-maintenance home which will last for generations whatever structural system you use.
Here's the New Yorker reference: an entertaining read, if only marginally relevant to good building practice.
http://www.newyorker.com/reporting/2013/01/07/130107fa_fact_green#ixzz2GjJj8JNX
I appreciate your point Lucas, I think it is along the same lines of what James is getting at, a traditional wall done right will suffice. No need to eliminate mold fodder or put in the high power bilge if the overall design is done right. Wanting to use stucco or EIFS, the motivation to eliminate variables that can lead to failure is high. With similar costs and overall performance (if not better) why not put in the high power bilge (given its already a tight stable ship)?
Conversely, what we think is a thoughtful design today, may prove flawed 5-10-15 years from now. Our friends who bought the brand new home in Bryn Mawr, Pennsylvania on an acre in an idyllic suburban setting had no idea 8 years later the nightmare they'd be part of. Yet it seemed a well done home by a respectable local builder. If only the builder could had known what we know now, well pointed out in Lstirubek's article:
http://www.buildingscience.com/documents/insights/bsi-029-stucco-woes-the-perfect-storm
So if I can eliminate the variables that contributed to that, why not? Trying to be objective, I ponder what unknown flaws the "new" steel and poly-iso wall design harbors, potentially only to be known years later. Wall assembly models and testing tries to give us insight, so far it seems said design may be a good idea. I'm awaiting cost analysis, and hoping to avoid inattentional blindness. Thus these postings, thanks for the discussion/ your input
You have bypassed one of the best solutions out there today: Pre-cast insulated concrete panels made by Superior Walls. I am a NC Coastal Builder and only build hurricane resistant and energy efficient homes. All of my homes us SW panels, spray closed cell foam in the attics and stone coated metal roofs over 5/8" decking. All windows and doors are impact rated as well. The Superior Walls are inherently waterproof by using 5000 psi concrete. That means I am virtually monolithic from the footer up to the rafters. This type of construction is also wild-fire resistant. Check it out.
Thomas, I am looking into all options, including ICF and CMU, above grade, not just foundation. I appreciate the reminder. Superior walls concern me due to their "virtual" monolithic construction. The panels seem to be bolted together after application of a sealant caulk. So it seems their achilles heel is that sealed seam, With ground movement and weathering of the sealant, I am skeptical the seal and seam integrity would be maintained. As I am in the process of pricing all feasible options I plan to look into it as well. It has an interesting design, outer concrete panel with steel structural members isolated by Dow styrofoam. Thanks
James Morgan wrote:
"Pay attention to these guidelines and you will have a low-maintenance home which will last for generations whatever structural system you use."
Interestingly, the studies I have seen on what affects the longevity of North American houses have much more to do with changes in land use, demographics, local economic conditions and style rather than the relative robustness of the structure. These other factors are statistically by a large margin what decides whether over time the building is maintained, renovated or demolished. Sort of depressing I know, but that is the reality.
James:
Jin is referring to something I (and probably others) have been aware of for a number of years.
I photocopied the article below almost 7.5 years ago. I found it on the web, but the online version is lacking a chart that would be most applicable to Jin's point.
However, I will call out the last 2 paragraphs of the article:
"To some people, reforestation projects, like the ones the Rolling Stones arranged, seem like the most appealing way to offset emissions. In one case, a power company paid $13.7 million to reforest 100,000 acres of U.S. Fish and Wildlife Service land in Mississippi in the expectation that every acre of trees would absorb enough carbon dioxide to offset 150 tons of greenhouse-gas emissions over the life span of the trees. But critics say such these schemes are much less effective than advertised.
“Basically, they’re selling a warm, fuzzy feeling,” says Dennis King, a University of Maryland researcher and the author of an EPA-funded study of carbon sequestration. Young trees don’t actually start to sequester significant amounts of carbon dioxide for 20 years, he says, and it takes a tree 100 years to remove a measly 3,000 pounds of carbon dioxide from the atmosphere—assuming the tree survives drought, fire, flood, disease, and other afflictions. ... Moreover, most of the carbon that gets sequestered in these forestry projects will eventually be released again when the trees die and decompose—or get harvested. “The numbers don’t look good when you work them out,” King says."
http://discovermagazine.com/2005/aug/25-counting-carbons
P.S. Thanks for the link to the New Yorker article. Mr. Robbins is a very interesting character.
The primary reason I opted not to frame my house with steel was by advise from my insulator (cellulose) who is also a fireman. His firefighting perspective was that a burning structure will give fairly reliable clues to structural stability when framed with wood. Metal structures get to that magical temperature where the metal turns very quickly from solid to liquid. He said as soon as they determine a structure is steel framed, all firefighting efforts are immediately limited to the exterior of the building. Absolute evacuation and no re-entry aside from human rescue effort. They would not fight the fire on the inside if the building was believed to be evacuated.
JML
Mike: while agreeing there's much to be suspicious of in the highly leveraged and over-hyped carbon offset market it's just not true to say that the forest contribution to carbon sequestration is unimportant. In the United States in 2004 (the most recent year for which EPA statistics are available), it's estimated forests sequestered 637 MegaTonnes of carbon dioxide. Urban trees sequestered another 88 MegaTonnes. This represents about 12% of the combined carbon emissions from US fossil fuel combustion. Forest products that go to construction-related uses represent better and longer term storage of this carbon than if it's left to rot on the forest floor. According to the IPCC "a sustainable forest management strategy aimed at maintaining or increasing forest carbon stocks, while producing an annual sustained yield of timber fibre or energy from the forest, will generate the largest sustained mitigation benefit".
Malcom Taylor makes the very valid point, if I can paraphrase, that a lot of what we build today is the wrong structure in the wrong place and will therefore endure for a much shorter term than it's capable of. This does nothing to refute the reality that when we DO build with care the right structure, in the right place, using forestry products like wood framing and cellulose insulation, we are capable of ensuring the sequestration of the embodied carbon for a very long time, at least by ordinary human standards. The carbon benefit compared to steel, petrochemical and concrete construction products may be marginal, it will certainly not be enough by itself to save the world from catastrophic climate change, but it's there. By those lights, we should use as much durable forest fiber in our buildings as we possibly can.
James: I agree entirely and didn't mean to imply we just give up. I do think that given the relatively short lifespan of our current housing stock it does behove us to build in a way that means the components can be salvaged or decay back to their constituent parts - as has been the case with all indigenous architecture throughout history. Building with materials like poly and foam are in that context recent aberrations, the consequences of which are still unknown.
Malcom: yes. There's also a very good carbon-management case for sending unreusable demolition lumber to burial in an anaerobic landfill rather than just letting it decay. Release of sequestered carbon can be delayed for centuries in this way, so even short-life buildings can contribute.
I do understand the point that James is providing, as every solution or "helper strategy" can possibly help.
The problem i have with this particular point, how much of mass does USA and Canada use for house framing and sheethings ?? how does it compare to the total mass of the forests of those country ??
i am pretty sure that the numbers are immensly distant.
Then, when u cut down a grown up tree NOW ..and u replace it with a young-ling, that won't be working as pointed out by Mike, until a certain period of time, to fill its carbon duty.
( that point could be rendered useless depending on the % of tree mass that is used for framing )
Other small point, have u ever seen branches brought back to saw plant to make lumber ?
only the trunks are used as far as i know, which leaves everything else dead on the ground.
I'd say, we better leave the current forests alone , use our already ocucpied territory to plant trees that are going to be used solely for the purpose of lumber
( i'd like it very much if they'd plant lines up of trees everywhere there is some free space around here !! would make it "forest" beautifull ! )
Personally, i believe that moving to clean energy and reducing our ridiculous personal consumption is the key to earth future. ( after educating everyone at school grade about earth's functions and our impacts )
We use hydroelectricity here in Quebec, and i a proud user of this almost clean and fully renewable energy source :)
Jon Leeth: the primary reason you decided to build ur house in lumber is that a firefighter told ya that steel doesn't hold good in a fire ???
1st off, when was the last time u saw a firefighter team actually try to save a burning house, and actually entering it ??? never locally hapenned to my knowledge, unless the fire is very very weak or there are still people in the building.
2nd : they learn at firefighting school that commercial or industrial type of open web steel joists under severe heat, give in very rapidly ( these joists hold up in fire very good, up to the point where the metal starts heating up to plastic mode and then tension rips it ..which is nothing special )
does not have nothing to do with walls, and to fuel a fire to that kind of temperature in a residential building ( with everybody out = not much live load ) is probably impossible, unless u are storing some fuel reserves in ur living room ?
Lastly, fire needs things to burn ... if your walls are steel frames on which gypsum boards are attached, and your floors are steel joists with steel deck , then what fuels the fire ??
sure your "cup board" made out of wood will burn, and will probably burn off the paper on the gypsum, then some part of the ceiling ... then what ?
or electrical wire in a metal box int he wall might set the fire on the wire platic sheathing...then it will melt some of the insulation ...and then ??
i'd take a metal/concrete house anytime over a regular wood framed house as far as fire security goes!!!
Jin, I am president of our local fire department and what Jon says is exactly what we train our firefighters to do. Houses framed with steel studs still contain all the other combustible structural components and contents that fuel fires. The unpredictable collapse of light steel stud walls is a well known phenomenon. Whether that's enough of a worry to influence your choice of materials when building a home is another question.
Back to topic, anyone took a few seconds to look at the skybuildingsystem link i provided ?
what do you guys think of their cold rolled system ??
http://blueskybuildingsystems.com/
i like it, just curious to hear and analyse ur thoughts !!
Having a home that is essentially non-combustible is appealing, to me. I favor CMU, ICF or steel construction for all the same reasons over wood, Stronger, longer lasting, no substrate for mold or decay organisms. What is there to burn? Yes, furniture, cabinets, tapestries, then what? The structure itself is not a fuel source. The idea of a steel deck with poured concrete throughout the house with radiant heat would be ideal! That thermal mass with it's structural integrity sounds nice. When we talk about steel framing, their may be light gauge steel, but the structural members have to be quite significant. (I am looking into the details) Given all variables equal, R-value, cost, ease of construction, I'll take the masonry and/or steel any day over wood. Life expectancy of steel/ masonry over wood is significant. Thus why hasn't steel become more popular in residential structures?
Sal Lombardo: ok, please detail waht other structural components ?
though i missed the real topic : steel-framed ..then if only framing is replaced with steel and everything else stays the same, might still be some fire risks ... but shouldn't that eliminate the fire transmission and "in wall " origins ??
Sal: i'm quick to say "cost" is the main factor ...thought it is just a a feeling ...
Jin, if you look at the Blue Sky Homes system you pointed out, the walls of such structures are NOT weight bearing. Kind of like timber framing. Certain structural elements bear all the weight of the structure (corners and in-between posts), while walls are mostly for holding up insulation and siding systems. Given its steel, it can span much greater lengths than wood or engineered wood, with much less weight and greater rigidity. Cost??? To be determined
Sal wrote:
"Life expectancy of steel/ masonry over wood is significant. Thus why hasn't steel become more popular in residential structures?"
Mainly because of its expense. Architects and developers try and use wood frame where ever possible even in large multi-story buildings because of the cost. They have to be essentially forced by the building code into going with non-combustable construction at a certain scale for safety reasons.
As I said in an earlier post, a building's longevity is very rarely determined by its structure, so that doesn't provide much of an incentive to use steel.
SAL: that is a reason why i got to look at that system ...removing load from walls, longer span without too complexe system, mostly bolted through... it looks nice to work with and assemble.
I have no idea of pricing, as they only do from design plans price with engineering.
also this kind of system could be best option ( steel would be obvious choice ) for a remote cabin/house type that has limited equipment and transportation weight.
any other similar systems that we can look at online ??
James Morgan,
Last night I finally got a chance to settle down with the latest New Yorker. I agree with you that the article on pickpocket Apollo Robbins was fascinating. A fun read.
Jin check out
http://www.scottsdalesteelframes.com
on-line quite a few outfits that will create a "kit" to erect a residential structure in steel. Not all with non-load bearing walls though.
SAL: yes interesting, but looks much like all other steel framing systems.
They change the material, but keep the same building method ..
it may be good for commercial buildings, but i think that there is way too much metal in there for it to
be efficient ( cost VS performance )
Exactly what i like about bluesky system, only what is required to hold up everything
the rest is supposed to be insulation neway , so why try to make the insulation load bearing or inside a load bearing wall ??
I am sorry if i always tend to stir toward 100% exterior insulation, but it is hard for me to accept
something else than the best i've seen so far, and in any case it is still either ICF with a thickened exterior foam shell, or any framining method with 100% exterior insulation.
The only problem i see about the C beam skeletal framing method, is that it could proove hard to
install the air/vapor barrier between the metal frame and the insulation ...
Sal, several of your claimed advantages for steel are contradicted by real-world experience and laboratory testing. You may prefer your vision of what ought to be true, but negative experiences with light steel framing are at least part of the answer to your question of why light steel studs aren't more widely used in residential construction.
While it's hard to light a steel nail with a match, there is widespread agreement that light steel framing performs poorly in fires. This statement has already been posted by several people in this thread, while those claiming "fireproof" haven't offered any evidence for their position. I recognize that saying it again doesn't increase the credibility, so I merely suggest that those actually interested in the question do some research with whatever authorities they choose to trust.
Sal says that light steel studs are "super strong", but by every measure, they are weaker than wooden studs. They are engineered to use the absolute minimum of material, to meet the design strength. They are designed to be "good enough" and they are exactly "good enough". I have no complaint about that, but it is silly to pretend that they have remarkable strength. If they did, the manufacturers would make them even thinner and lighter.
Sal says that light steel stud framing "lasts forever" and that "Life expectancy of steel/ masonry over wood is significant." I challenge anyone to support that contention with building science references. Without specifying more details about the design, construction, climate, and maintenance parameters, I think these statements are meaningless.
Sal says that light steel studs are "not affected mold". While true, this masks the companion decay mechanism for steel that is certain to be present if mold exists, and that is corrosion. Steel studs can do nothing to buffer moisture, and the same is true for the more common insulation types used with them. This puts steel at risk for corrosion in moisture conditions that are not a problem for wood studs. In addition, steel's thermal conductivity makes it a likely location for any condensation within the wall. I've read several building science articles documenting this problem, and they show pictures of steel studs that have corroded at the bottom, such that the wall is being held to the bottom track by the drywall and sheathing, more than the studs. I've seen this myself in the high desert of New Mexico, where buildings are at a lower risk to moisture issues than almost anywhere else in the country.
Steel has advantages and disadvantages, like every building material. It makes sense for each person to choose the combination that they prefer. Accepting the rosy picture of any material painted by the advertisers is a sure ticket to disappointment.
Derek, I'm not sure I know what you mean by "You may prefer your vision of what ought to be true"? Since I am not delusional (in as much as perception of self will allow), nor am I a steel salesman making claims about my product, I do not prefer any vision of what "I'd like to be true". I am looking for objective and if possible, scientific information, on steel framed residential structures. I got some good info and enjoyed the discussion with individuals that share building science as an interest.
Its one of the wall assemblies I am investigating, among ICF, traditional wood, CMU and the most likely to be used, based on what I know so far; a hybrid thereof. Thus I started a discussion to get input from a variety of sources. I have no personal claims about steel, can only relay what is perceived as accurate from the general understanding of the material. Recall this Q and A started with my question.
I appreciate the points you make regarding steel framing. Its exactly what I want people such as your self to share.
Thanks for participating.
Steel buildings require added insulation as steel on its own is not a very good insulator, which will be costly. Apart from this, the cost of making steel is very high. It takes many of times more to assemble a steel frame building than a normal one.
Jenny Belman: additional insulation ?? seriously ??
price of steel is very hight?? you mean the steel as material or pricing that we get when inquiring from building contractors that take a hefty 150% margins over products?? :p
Please re-read all of the thread ... you may edit your post also :)
Derek: as far as i know, nobody gave proofs over the "dangerous situation" of using steel in residential buildings when a fire arise...
from what i could gather, firefighters spread the word that "steel" frames are dangerous becasue they were told so ... and this comes from "structural steel joists " giving in when the teamperature near ceiling becomes close to strength weakening temp of steel and brings its tensile strength sufficiently low that it cannot support the load on top of it.
Then, why are u all only considering super light gauge wall framing methods ???
personally i wouldn't trust that for load walls at all, and that is reason why i pointed out to bluskybuilding system, because it uses much thicker metal "beams" for weight loads.
Then, let's say ( again ) you have nothing to fuel a fire, how hot will it really get ???
i mean c'mon ... steel + concrete+ gypsum building ...
what is burning other than your furnitures ???
i am sorry, but a single sofa burning up on an engineered wood floor
( the wood floor will not even burn ) residing on a concrete floor,
against a gypsum wall ( with steel studs )
will not even raise the temp of the single room high enough for other things to catch fire
( even less to render any metal supporting frame plastic enough to give )
Can we stop talking about "burning steel structures " now ??
Downsides of steel structures is it's non availability and pricing
i don't see any other
and i don't see why using 100% exterior sheathing insulation is not on your mind
when you think about steel structures.
that also takes care of rust , condensation, and steel thermal performance.
back to topic:
SAL : i do not know much about Zone 5 requirements but i'd be tempted not to venture too much out of what is available locally if you do not plan or cannot do it all urself.
Are you hiring someone to put up the frame or are you doing it yourself?
this changes things greatly, because i wouldn't ask a team of experienced wood framers to build
my house with a new steel product that they've never even heard of ..usually is a good recipe for errors and disasters .
Why not consider ICF if it is available in your area ??
I do not believe that it should cost more than steel framing, and it has even a better
fire rating performance
Sips might be a good alternative to wood framing if price is right .
Are you planning an R30 walls that includes in the calculus the "inframe" insulation ??
Because R30 of pure insulation foam and R30 total wall including insulated framed partition
is different as pointed out many here with studies
( stuff like R20 batts in a 2X6 walls really only end up being R8 .. just giving random example here )
cost effective is super important in house planning, and try to guess how long you will
be living there ( if you plan on moving on in 10 years ...a longterm investment on insulation might not be best option for your pocket! )
Jin: don't kid yourself about structural steel fire performance:even heavy grade hot rolled steel framing members turn to limp noodles in a fire (first pic.). Moreover, unlike wood, they do so suddenly and catastophically. By contrast the Butler Square building in downtown Minneapolis was approved by fire officials with a nine-story internal atrium supported by unprotected timber posts and beams (2nd pic.).
Just saw this posting while looking into some issues for a commercial building. Wondering if others saw these two sites that may provide additional information on steel framing:
http://www.toolbase.org/ToolbaseResources/level4FAQ.aspx?ContentDetailID=1443&BucketID=1&CategoryID=35
http://www.steelframing.org/index.php
Every building material has its place and warmer climates would be more steel-framing friendly. I
This company may be getting involved with a project of ours on the Gulf Coast that can't have wood framed walls. I may have more information to report later, but we are proposing a hybrid insulation approach with some blown cavity and exterior insulation.
http://www.lightgaugesolutions.com/
Here is an interesting flooring system, cobines steel structural members and a concreter slab which could be used with radiant heat to creat a thermal slab.
http://www.hambro-floors.ws/www/v4/ehambro.nsf/floorsystem/d500-description?open
they claim "up to" 4 hours fire rated. Not sure anything is "fireproof", but fire resistant, more so than wood I would imagine.
Jin, I absolutely am considering ICF. I saw the question you posed on the GBA Q&A, "What is the downside to ICF", thanks for asking, you read my mind. I've only ever framed with wood, like the idea of ICF. interested in the costs. ICF walls, structural steel joist with overlying Q-deck and concrete slab with radiant sounds like the way to go, again, what kinds of costs are we talking about?
Thanks Debra, your link is spot on, the Steel Alliance site has a plethora of info, will look over it in more detail. Their home web site claims the many advantages of steel we're debating here, efficient construction, strength, non combustible, lower costs to insure vs wood, termite/pest proof, straight members, long term durability......
SAL: ICF components usually go from 2 to 4$ per sq of wall area.
Then u add on rebars ( not that much $$ at all unless very complex design)
and concrete cost ( high quality concrete, not the cheap stuff )
I paid around 27 000$ for all of my steel joists and steel deck
that is for approx 4800sq ft of deck and the underlying steel joists ..was from Canam
also my engineer put only 50lbs/sqft of deadload , and 40live
had i knew, i would've asked for 70lbs dead to have some over, because it does not change the price of the joists much ( only a small % higher )
i was going with a 5" total concrete slab on all decks ( doesn't give a real 5" because of the forms)
and i've used in slab electrical heating wires for all the heat of the complete building
works superb ! but electricity is cheap here and green !
Also i would've added a minimum of 2" additional foam on the exterior,
but i didn't even know back then, that it was possible and or valuable :p
do your homework, get quick quotes for components.
I'd consider ICF again up to let's say 15% high house cost ..more than that you might
check out other options ...
Greetings - just came across this site. I am considering building a steel frame home in Chino Hills, Ca.
We are relocating from Miami this summer. I have followed advancements made by an architect from Virginia .. Mr. Angus McDonald. His company Am-Cor Inc., designs and builds "ferrocement" residential and commercial buildings in the US, the Virgin Islands, and even a luxury home on the Isle of WightT.
His "system" is:
-galvanized steel wall systems are bolted to the footer.
-galvanized roof trusses set after the base structure has been final plumbed, and unitized (screws,
field welds etc).
-the exterior of the structure is wrapped with a carbon steel lathe .. applied with galvanized screws.
-Angus has a patented stucco compound that expands the same rate as steel .. and will not
crack when used as an exterior stucco. The exterior lathe has an Amcorite stucco compound
applied (base coat ... then finish coat). Once the stucco is applied it can be sealed and painted,
or a 3rd coat can be applied with a color tint and a ceramic powder for a life long color application.
-I have visited a 7000 sft day care center in Virginia that used this system .. combined with a bauxite
treated roof sheathing .. and the structure was rated "fireproof" by the county and did not require
sprinklers.
-I also visited a 3000 SFT home / photo studio and a 4400 sft luxury residence near Naples, Fl.
They currently use steel "tile look" roof systems .. but have also developed steel lathe systems that
accept the same "Amcorite" cement for a permanent concrete roof. The luxury home I visited used some sort of injected closed cell foam insulation applied to the roof and the exterior walls. All structures have low energy consumption. So I am not sure if the cement exterior assists in reducing the thermal bridging .. but I am glad I came across this issue. I will be asking Angus for comments.
Thanks,
Rick
Hello I have been following this discussion with interest.
I used to Like IFC's in theory. But when you do the Math you Will find you're paying for a lot of unusable floorspace.
I'm not a professional builder but I've experimented with a lot of alternative building methods. Adobe, ramed earth. I currently live in Northern California in a Stone house I've built myself.
I want to build a modern house in Southern California. As there are no flat lots left in Los Angeles County. I will probably be building on a hillside.
The tentative plan I've come up with is to use a cold rolled steel I beam C beam Load bearing superstructure.
I put up a few agricultural steel buildings Using this technique and it goes up extremely fast. If you have architectural plans you can order your beams Precut.
For exterior cladding I've been thinking about using Georgia-Pacific Dens Glass gold. It looks like drywall but there's no paper involved. It's infused with fiberglass. I've tried burning the stuff with a torch and it won't burn. Also I've heard that you can submerge it in water for a half an hour then cut into it And it will be still dry. This I have not personally tried.
Then Covering the DGG exterior with fiberglass or Lath and plaster backed Portland cement stucco.
The flooring would be steel floor decking covered with diamond polished concrete.
I'm trying to figure out what sort of infill walls I will use. Wood or steel studs?
What sort of insulation?
I'm looking for heat insulation, mold resistant infill walls.
With regards to Skyblue homes the packages are fairly expensive. I think they run about $350 a square foot.
The panels however are manufactured by another company.
The company is called K tect.
Why are you people so obsessed with stud thermal conductivity?
Stop thinking Light Steel Frame and start thinking about this type of construction: http://www.houzz.com/exposed-steel-beams
Mask,
Q. "Why are you people so obsessed with stud thermal conductivity?"
A. Because most homes with steel framing include some horrendous thermal bridges. This applies to some of the homes on the page you linked to -- for example, the houses in the photos shown below.
.
Why did you have to go and look precisely for a picture that does not stand for what I mean. Those houses are terrible, yes. Just take a look at the first photo in that site. (I hope I managed to attach it). If it has all the studs/beams on the inside like we see in that part of the home, is it not a good example on how to work around LSF and Thermal Bridge problems?
Brgrds
Mask: framing , especially metallic one goes inside.
Period.
I do not understand why we are still discussing/debating about thermal bridges.
Exterior insulation is the key, everybody knows it, most are still afraid.
Now we need some brands to come up with insulation that is affordable and has good fastening strips on thick panels and is green.
Before using steel studs check with home insurance cost. Buildings of these construction will collapse very quickly in a fire. fire department may have experience with this. I live in Ca and for a few years now I have not seen this construction used, it was common several years ago. there must be a reason other than cost.
I am a former Air Force crash rescue officer and an engineer. Fire on one side of an insulated steel stud will cause that side to expand -- this will bow the stud and a bowed or bent column is very weak in compression.
Bill
William : why do you bring up this almost year old thread to revive the "fire alarm" that have been discussed already on page 1 .
Look at the photo linked by " The mask" 2 posts up.
Tell me how inside temperature ( other than a burning leaked natural gaz line ..lol ) could rise high enough to have steel structure fail ? We arent discussing 10 stories buildings on this thread, but rather residential buildings, mainly single homes .
You need combustible to raise the temp, most recent designed homes involve rather large empty spaces instead of the cluttered unused articles houses of the 70-80's .
Then steel fraiming is usually designed with alot of " margin " .
I am not saying that it is fireproof or safer than other methods, i am only saying that it is completely IRRELEVANT to this dicussion to introduce fasle alarm/warning about fire problem in 2014 on USA/CANADA buildings.
Even more with mandatory smoke detectors that would get you out of the house 1 hnour before any possible thermal failing of steel frames.
Sal,
I'm not sure if you ever got your answer to the question but I would like to recommend Don Wheeler of Wheeler Construction. He is an expert in residential steel framing and has done numerous custom homes. His company also provides steel trusses and foundation forms that can be recycled into the build leaving no waste. Don is in the process of taking his company global with new building codes on our horizon, steel framing is a hidden secret. Coming from an Italian family and being a wife and mother, I wouldn't do my house in anything else. I have found it to be the best way to protect my family from so many elements. Speak to someone who specialized in the niche market and has accomplished working on a Platinum LEED rated home.
In my review of green insulated steel-framed housing, I came across an interesting company called GigaCrete, Inc. based in Las Vegas. They make a steel-framed insulated modular "GigaHouse" which is encapsulated in their green non Portland stucco and plaster that form very hard surfaces. Rather than try to describe how they dealt with the problem of thermal bridging etc., this from their Facebook site seems to sum up the invention.
"The home (GigaHouse) utilizes GigaCrete's complete building system that incorporates 6 inch EPS foam walls with 18 gauge steel studs providing a true R-22. This is accomplished by embedding our steel stud within the foam eliminating any thermal bridging. The EPS foam GigaRoof touts an impressive R-46 even with its vaulted ceilings and a 200mph wind rating. The exterior foam walls and roof are coated with StuccoMax providing a 3,500 psi waterproof finish. The interior foam walls and vaulted ceilings are finished with PlasterMax our fire resistant plaster that has an impressive psi of 8,500. In addition, PlasterMax will not support mold or mildew and has zero VOCs."
Sal, I know that this discussion is pretty old, but I wanted to know if you ever built a steel framed house with radiant floors?
Great discussion, thank you!
A properly built wood framed house can last hundreds of years. I think using SOME steel is important and helpful. But I do not believe it can be done cheaper than framing lumber by any means. Nor will remodeling or modifications be any easier as styles and needs change over the centuries that the house will stand.
Now I see some chat regarding fires and what holds up to a fire. Let me set the record straight. The reasons a house burns quickly has nothing at all to do with the framing material. It has everything to do with gobs of over stuffed furniture made with synthetic material, MDF (crap) furnishing and draperies, textiles etc that are synthetic and highly flammable. Although European housing uses a lot of steel studs, we all know that their framing systems include soundproofing and measures to reduce noise and vibrations. I simply think that using steel framing is not a practical solution in the land of cheap new growth lumber.
I'm sure the values in the table Martin posted at the start of this thread are right. But I think the values greatly depend on the shape of the steel. If an H or T profile is used the area of thermal bridging is very small. 0.2" vs 2" of a 2x4 wall. So while the conductivity of steel is much higher, the area to transfer is much smaller. So it may even out.
Tony,
I'll publish the table again below so readers know what you are talking about.
You wrote, "So while the conductivity of steel is much higher [than the conductivity of wood], the area to transfer is much smaller [if you choose steel studs with an H or T profile]. So it may even out."
Really? "It may even out"? Do you have any data or measurements to back up your guess?
.
Sorry Maryellen, never got back to you. Lost track of this thread. No, never did the structure in steel. Among many of the drawbacks, one of the handicaps was the complexity of the design. A large rectangular box better would lend itself better to such an experiment.
May revisit the issue some day!
Thanks for this question, it is one I have been asking. I intend to build a steel framed house in Jacksonville, FL. The answers have been informative, I hadn't thought of the insulation problems, but y'all have given me solutions to the problems. Between insect and hurricane damage, I feel steel framing to be a viable choice. Obviously, I needn't worry about cold, just heat. But then, I was born in Boston and got out of the cold as fast as I could. I moved here from South Texas. I'd rather it be 90 than 50. I've been looking at steel framed homes for years, now I may be close to selecting one. The model I fell in love with years ago, from Steel Framed Homes, Inc. seems to be no longer available. Since I retired, most of my time is spent cooking. It's amazing how many homes have tiny kitchens! I guess they don't realize that if you entertain, everybody is in the kitchen. Still checking all the companies.
Gregory: In hurricane country steel framing doesn't buy you nearly as much resilience as building with concrete or masonry, and with a mass-wall you can do with less total R.
The U-factor of an IRC 2015 code-min wall in US climate zone 2 (Jacksonville FL) would be U0.084 (or about R12 whole-wall), whereas for a mass wall (CMU or concrete) it only takes U0.165 (about R6 whole-wall), per TABLE 1102.1.4 (see: http://codes.iccsafe.org/app/book/content/2015-I-Codes/2015%20IRC%20HTML/Chapter%2011.html )
A steel framed 2x4 wall with R13s would still need a continuous R5-R6 (depending on siding type), but a CMU or concrete wall would only need the R5. When hurricane force winds arrive masonry walls will be much less susceptible to wind damage or wind-flung projectile damage than even a brick/stone veneer steel framed house.
I live in a steel house I had built 22 years ago in the treasure coast of Florida. The first floor (1750 sq feet) is concrete with interior 2x4 12 gauge metal studs. The second floor (1600 sq feet), joists, rafters and Trusses are all 2X6 12 gauge metal pieces and everything is screwed together. The two 3.5 tonne air conditioners run pretty much all the time. I am on a well so I have a water pump running for house and irrigation of 3/4 acre of land and a pool pump that runs 8 hours a day. My energy costs averages $285 a month. I also have been hit head on by 3 hurricanes from 117 to 127 sustained mph with no damage. I am happy with the house.
I once researched steel as a (low rise) building material, but I concluded that there were no significant advantages to it, mostly drawbacks. Extra cost especially, although the recent -and hopefully temporary- big spike in lumber prices may give steel a slight advantage in some cases these days.
Most of the benefits mentioned in the original post such as "Super strong, straight, minimal waste, not affected by termites/pests or mold" can also be achieved with dry wood. In a residential setting, water infiltrations inside a wall need to be prevented diligently (or addressed ASAP when they happen) no matter the framing material. And wood that's kept dry lasts forever.