In a report released a week after the incident, officials with Berkeley’s Building and Safety Division confirmed suspicions that dry rot had deteriorated the wood beams supporting the balcony. They also said they found no construction code violations. — latimes.com
It's been a week since the tragic balcony collapse occurred, and while the victims' families try to cope with the grief, experts have been searching frantically for the cause of the accident. Was the fault in the structural design? Is the contractor to blame for poor execution? Speculations quickly ran wild, and the comment section of Archinect's news post quickly flared up.
The newly released report seems to have determined the cause of the collapse, but the debate on how to improve existing building codes (and properly enforce them) has just begun.
45 Comments
hmm... where I came from wood decks + balconies are always exposed, with the decking spaced to allow drainage between boards. Presumably to ensure it dries out.
Exterior wood decks always eventually rot (not usually this quickly) - the worst thing you can do is close it in like this so that the rot will be hidden.
Isn't exposed wood no longer allowed in California (in many instances) due to wildfire concerns? I realize this building isn't out in the wild hills where fire is common, but my sense is that fireproofing concerns may have led to a certain enclosed way of building that is in conflict with allowing moisture to escape.
Lots of unsavory details here. STO is notorious for trapping moisture and causing rot and black mold.
I just read that the apartment building is less than 10 years old. Geez. Such tragedy might be averted if we still had aspects of the building code of Hammurabi in effect today.
Dryvit is crap, and cantilevering wood joists when you can't see how it's performing is nuts. A couple of visible metal brackets securely bolted to posts would have done the trick. My heart goes out to those young people who lost their lives here. Hopefully the code books can learn something from this tragedy.
waterproofing should get better defined in the code. you should require moisture readings at specific locations in projects like this after a year or two before close out, if you are to detail such crap.
The code is not the answer when it comes to details. Structural requirements for building type - yes, how to waterproof a door sill - no. Aside from that it's simply impossible without the standardization of all building components. Wood frame low-rise is the start of all the problems here.
Lots of things are essentially designed to fail for various reasons including lack of knowledge / experience / foresight, insensitivity to materials, cost cutting, focus on "aesthetics", etc.
Miles I do not agree. You have an unsafe condition here caused by poor detailing. Not doing a proper fire proofed enclosure is not to code for health and safety reasons. Not doing a proper water proofed detail caused deaths here. There is no difference. I do agree wood frame should be kept to detached 1-3 family types only. as you noted on the other thread NYC requires this now. NYC sets the bar here, one of the oldest codes and most developed etc...
The simple reality is that all buildings leak somewhere. You just don't know until there is visible sign or failure.
Creating envelopes that trap moisture (STO / DryVit) on structures subject to moisture damage (wood) is asinine. There have been national class action lawsuits over artificial stucco for decades and this shit is still being used in wood frame construction.
In this case elimination of either wood frame or STO would have prevented the problem. The code allowed the problems. Bad design and detailing made sure they happened.
You don't waterproof wood construction. Just DON'T. What you do is have the wood breath. There should be pathways to allow water to discharge and not trap water or moisture.
For exterior application, you should use spaced wood decking. In areas where fire is concerned, use ipe or a synthetic alternative to wood decking.
In areas of California, wild fire / brush fire is not a big concern, in those situation where wood is permitted then don't wrap it. Either use fire-treated wood, Ipe, or a fire-resistant synthetic product that looks like wood. In any case, the product should be water resistant. In any case, it really should be exposed but also when using wood, EVERY cut joint should be treated. In addition, two times a year, the wood should have a coating of water resistant treatment where the wood would be bead up and roll into the channel gaps.
TWICE A YEAR. SPRING AND FALL. Basically March and September for California typical weather. You can do it once a year so it should be applied during dry summer months a little before wet season comes.
It doesn't matter if there is subtle leaks of moisture. What matters is moisture isn't trapped. As long the building (and any components or assemblies) can discharge excessive water and allowed to breath (let evaporation of moisture out of the wood in a timely manner. What causes wood rot is extended duration of moisture softening and eroding the fibers and then discharging. It is that there is a cycle. If wood is perpetually under water... no wood rot issue. Rot happens when the moisture is trapped in the wood for an extended duration and then discharged because even buildings that do trap moisture... it does get out eventually but far too slowly.
The moisture discharge and arriving back to nominal moisture equilibrium rate should be about 1-3 days after a heavy rain. It should breathe and discharge excessive moisture from rain storms in about 1-3 days of dry weather. This is why old buildings from the 19th century that are made of wood tends to last over 100 years. Even 50 years. In addition, ALL exterior wood use should be P.T., Cedar, Ipe or other weather and water resistant wood that is suitable for exterior use.
If the wood used was Sunwood, there is a problem right there. What was the wood used?
Never use things like carpet, or anything that captures/absorbs alot of moisture and discharge it onto the wood and let water stand still and never let the moisture be trapped in for extended length of time that is unnatural duration.
Wood is a natural product and therefore has natural duration that it can retain excessive moisture without rotting out (or at least at an excessive rate). Yes, wood over time will nonetheless slowly degrade but that's acceptable when you are looking at 50+ years in properly maintained.
Richard what the hell is the purpose of roofing if not waterproofing? so you are building bathrooms without any waterproofing membranes? ...................Miles, as you know lawsuits happen and then sometimes codes change. this is why NYC is best for setting the bar, because for every new code there is a knucklehead that goes around to which the city responds with a new law.........in this case either you ban wood structures for anything beyond detached family dwellings or you ban enclosed wood decking or you require minimum waterproofing details with follow up controlled inspections, just like you do with fire proofing. mulitple deaths qualify/warrrent for a new law.
I fully anticipate a change in codes and said so previously. I don't expect it to be well thought out though, more influenced by the inevitable lawsuits than by an objective analysis of the situation. Adding new layers to a code that is deficient in multiple ways will not solve the underlying problems.
This shouldn't be handled like modern medicine where the symptom is treated instead of the cause.
^how would you propose to prevent similar incidents without resorting to a code change?
Somewhere in the last couple days I read an article that this same contractor has already been found at fault for construction defects leading to balcony collapse on other recent projects and paid out big money in damages. I can't look for the link now, pretty sure it was in the SF paper. So they already ought to know they're doing it wrong. They just don't care, apparantly.
I find it really strange that some are so quick to point to the wood construction as the problem that needs to be corrected in this case. It wasn't the wood's fault that the architect detailed the balcony condition poorly resulting in water infiltration.
Richard's post starts to get at the solution to the problem, but misunderstands the treatment. Allowing wood to breathe would help, but preventing water from getting in is the first step. It was this first step that was never achieved. Everything else could remain the same on this balcony, and as long as water was kept out, it would not have failed.
Regardless of the building type or the structural demands, if wood is kept below an appropriate moisture content it will not dry rot. If you want to solve a cause and not the symptom ... first, keep water out of your building. Keeping everything breathable and letting it dry out is fixing the symptom, not the cause.
mid - I was arguing against Olaf's idea to add a waterproofing code.
The code should be changed: specifically to prohibit wood frame for low-rise and to eliminate the use of EIFS on wood frame structures. I don't expect either to happen.
what is wrong with a section on waterproofing in the code? in nyc its financially viable to not use wood, but elsewhere probably not. i realize this is also partially related to climate, but so is the legally required frost line depth for a foundation, etc....if its not to code its a lot easier to tell the owner and contractor to redo. paying damages via your insurance while you make tons of money doing it wrong won't prevent anyone from carrying on.
Leaky buildings don't normally cause deaths. Fires do. And all buildings leak.
Use of wood in NYC is not about financial viability, it's about fire hazard.
poorly constructed byildings leak over time, not all buildings leak. most do not within 10 years unless designed and built wrong. miles the wood and financial viable point was about NYC having a market to support apedning more on materials and still make a buck. all but portions of Queens and Staten Island are in a Fire District (which made getting a copper clad wood pergola approved in Manhattan once a bit tricky...fortunately Hoover products provides alternates)
most Roof warranties (at least flat roof types in NYC) are 25 or 30 etc...this means no leaks.
So if a roofing company can guarantee this why can't an architect and contractor guarantee this in Accordance with a Code?
or Architects could just keep giving up parts of the process to various industries who know how to design and build.
Architects ARE increasingly giving up parts of the process to various industries including municipal codes that are often designed as much for industry and developers as for public safety. Which is no doubt why wood frame is still allowed in low-rise construction and why you can still put artificial stucco on it. You're arguing for more of this and some Band Aids to prop it up.
This is a tragedy. Adding a waterproofing code won't prevent it from happening again if the same materials are used in the same conditions. Thus the necessity of eliminating that combination of materials which has been repeatedly proven to fail in a variety of ways from structural to environmental. I see this as criminally bad design for which the builder will probably get screwed for following the plans. With a similar problem in his past he should have known better. Greed rules.
you should require moisture readings at specific locations in projects like this after a year or two before close out, if you are to detail such crap.
How can you possibly monitor the moisture condition of every sealed framing cavity in a single wood frame building let alone every one in every building? Better not to detail what is widely known to be crap - preventing it by eliminating such crap from the code would be a good start.
Better not to detail what is widely known to be crap
make that code.
I knew we'd agree eventually.
Now the only problem is who gets to define crap?
Miles, what leads you to think that this was EIFS (Sto, Dryvit, etc.)? I'm not finding any indication that EIFS was used on the balcony. Instead I'm seeing that it was cement plaster (stucco).
The problem here is simply money; there are prefabricated bolt-on aluminum balconies that would deflect the problem & liability. Additionally most balconies are designed for 100 lbs. LL, should be double, there is the needed code change….if these developers keep this up balconies will go the way of diving boards.
In the wake of this, California will probably wind up implementing something like the envelope design requirements currently in place in Seattle. Just from looking at that picture, nobody in their right mind would build wood construction like that in a multifamily project around here. Even if it didn't fail, you'd be sued out of existence in no time flat.
California is at the bleeding edge of seismic requirements, but apparently they haven't yet figured out how to keep water out of building assemblies. Maybe because they think it never rains there?
It gets pretty wet up here, and we seem to have figured out how to design and construct buildings -- even wood ones -- that don't decay into mush after a few seasons.
Intern, have you ever seen a real stucco job?
Miles, yes. Have you any evidence to support your assertion that EIFS was used on this project's balconies?
Aside from the pictures and all the clear visual evidence they show, the detail drawings posted, the history of EIFS failures including dry rot, the common use of EIFS in cheap shit development, no.
Olaf,
There is no such thing as waterproof at least 100% waterproof. It is not waterproof, it is water resistant. The thing with bathrooms is creating a water resistant barrier to block and channel water in areas such as showers and bath tubs.
The point is not let water get trapped in. The problem is once you have a means for water to come into the wall cavity or in this case, trapped in the floor, the issue of rot is the water is trapped and not dissipated fast enough.
With bathrooms, the reason the room walls are highly water resistant is because with showers and steam build up that moisture condenses on the walls, floors and ceiling. The ventilation is often not sufficient to move the moisture outside fast enough. What you don't want is a cavity that traps moisture inside and you can't let the structure breath.
Another thing you try to do with exterior walls is the allow keep dew point from occuring within the walls. But even then, you want moisture that ever gets in get out and not collect and stay for long duration. It is all about environmental control and moisture penetration management and control. If moisture is bound to permeate, you need to discharge the moisture.
In Oregon, EIFS is legal ONLY if you use a rain-screen. I would say, even Stucco needs to have a rain screen especially in the coastal Oregon region. Stucco and EIFS are poor products to use in areas subject to significant rain and even parts of California is subject to significant volume of rain in a short period of time especially as we have more and more extreme polarized weather conditions (ie. extreme wet/cold winters and extremely hot/dry summers.)
I would specify rain-screening even for stucco especially in northern Oregon coast and SW Washington. It is known to not perform well in long duration.
Not sure if you are looking at the same pictures, but I see no indication of EIFS. If there was EIFS you would definitely see bits and pieces of EPS foam insulation; that stuff gets everywhere when it breaks apart and is disturbed ... as would be the case in removing the failed balcony and the one below it. There is none of that shown in the photos.
The detail drawings I've seen are showing an assembly at the edge of the balcony and at the soffit that would not be thick enough for EIFS. You would need an assembly at least a few inches thick to account for the foam insulation. Rather it looks like it would be about the proper thickness for stucco.
If EIFS was used and with such a history of dry rot and failures, why has no news outlet keyed in on this? I have seen plenty articles mention stucco, but not EIFS. You would think that the connection to EIFS would be a no brainer, yet you are the only one I have seen make it.
Finally, the report issued by the City of Berkeley (which you can read for yourself here) indicates that the finish was cement plaster (stucco) and was needed for fire protection of the structure. EIFS, in and of itself, offers no fire protection; you would need to install it in addition to some other type of fire protection to get a proper rating. However, stucco does offer fire protection.
A failure in thinking the product will never let water in and then it fails to let water out.
Lack of drainage. This is some kind of cement product used.
Richard you are a moron, get back to me when you become an architect.
Richard, let me qualify that statement - your google searches tend to be fairly accurate, but your ability to exhibit comprehensive understanding of all elements in discussion is very much lacking. something you learn in practice whether by doing what you call illegal practice as an intern or even sometimes as a student. just about everything you say if summarized succinctly, if we throw out the google fluff copy paste crap, is essentially wrong. i would guess your purpose is DISINFORMATION on archinect?
You would need an assembly at least a few inches thick to account for the foam insulation.
EIFS can and is be applied to various substrates.
If EIFS was used and with such a history of dry rot and failures, why has no news outlet keyed in on this?
Your lack of knowledge does not mean the material is safe or reliable. If you want to be an architect you had better learn how to do basic material research.
The National Association of Home Builders (NAHB), representing over 60,000 home builders nation wide, told Dateline that synthetic stucco, even if it meticulously applied and maintained, "Isn't compatible with the existing wood frame construction methods in the United States." They went on to say that homes with synthetic stucco "develops moisture intrusion problems even when properly constructed according to industry standards"
Okay. Since Intern and a few others seem a little confused about this, here's a few things that are clearly evident (to an architect with decades of experience who lives in a wet climate) from that photograph:
1) While I can't tell whether or not the exterior cladding material is traditional brown-coat stucco or EIFS from that photo, the surface finish is DEFINITELY an acrylic EIFS-style finish coat. No question about it. So regardless of what's underneath that surface finish, the outside weather surface is trowled-on acrylic. Please note that this type of finish is pretty good at trapping water vapor inside an assembly unless there are plenty of flashings, weep holes, and and a drainage layer between the cladding and the sheathing.
2) Take a close look at all the corners and panels in the "stucco" in that photo. You will notice a couple of things: A) there are no control or expansion joints, not even at the floor lines, and, B) the acrylic surface finish is run right up into the door frames, both jamb and head. If there are any sealant joints at the opening penetrations, I can't see them in that picture.
3) Header flashings? How do they work? Are there any? I can't tell.
4) The lack of weeps, proper joints, and flashings means that there was probably a fair amount of water in the assembly back behind that acrylic finish. Whether EIFS or stucco, that water was probably trapped between building paper on the sheathing plane and the surface finish material. It was looking for a way out, which it found at the corner and pan flashings transitioning to that deck. Also, it wouldn't surprise me at all to find substantial rot back inside the wall framing and diaphragm.
5) The rot pattern on the deck joists is revealing. First off, I've seen rot like that before. That's what you get when you have water infiltration into a sealed assembly. The wood almost looks like it's been burned, which in a sense it has. But look where the rot is located. At the connection to the building, there is little rot in evidence. Most of the rot is located right at the edge of that flashing coming out from the door pan over the ends of the joists. And it occurs on every joist, not just one or two. That means there was continuous water seepage through the edge of that flashing into the deck assembly. The flashing, and probably also the deck membrane, were not detailed or installed correctly. This is the kicker, and where the liability will probably stick. Either the architect or contractor is responsible for that. Maybe both.
Miles, you might want to do a little more material research yourself. You are correct, "EIFS can and is be [sic] applied to various substrates." Synthetic stucco is a component in an EIFS assembly and can also be applied to various substrates. EIFS assemblies will apply synthetic stucco to insulation boards. If you don't have insulation boards, you don't have EIFS. Using the two terms, EIFS and synthetic stucco, interchangeably is incorrect.
I'm not denying that EIFS has historically had moisture issues related with it's use ... especially on wood frame construction. Many of those issues have gone away with more emphasis and education on water-managed EIFS (it still might not be the most appropriate cladding for use on wood construction). However, my point is that it does not appear to have been used on these balconies, yet you claim it is with nothing to support it other than your own interpretation which, in the face of actual analysis and evidence, is clearly flawed.
My issue with most of your comments on this issue have been that they seem to be largely based on conjecture, gut reaction, and fear without an attempt at understanding what is really going on.
If you want to continue the discussion regarding EIFS and its failures, history, appropriateness, etc. feel free to create a thread that addresses those topics. However, please stop spreading misinformation regarding the topic of this thread.
Thank you for correcting my less than perfect terminology, even when it was spelled out clearly elsewhere in my post. It's my mistake to use the term EIFS instead of the correct name of the primary component of the EIFS system.
synthetic stucco, even if it meticulously applied and maintained, "Isn't compatible with the existing wood frame construction methods in the United States."
Now that we have the correct terminology, the facts remain. See gwharton's post.
My issue with most of your comments on this issue have been that they seem to be largely based on conjecture, gut reaction, and fear without an attempt at understanding what is really going on.
As opposed to knowledge and experience? Intern, please enlighten us as to what is really going on.
Now that we have the correct terminology, the facts remain. See gwharton's post.
I see gwharton's post and agree that a top coat of synthetic stucco (acrylic-based finish coat) could have been used on this project. We do not know for sure. The report issued by the city does not mention it, but that does not rule out the possibility. As far as the facts, we'd need to know more about what was actually used to know more. I will also agree with gwharton's analysis that there does not seem to be sufficient attention to detailing properly with regard to managing water infiltration (flashings, weep screeds, control joints, etc.) ... this is problematic and more of a concern than the potential that synthetic stucco could have been used. This concern is not limited to synthetic stucco, it would also apply to traditional stucco or any type of cladding.
There are plenty of synthetic stucco coatings that have higher perm ratings than wood sheathing materials. OSB for sure, and plywood under certain conditions (less than 80-90% RH). The ones I've researched are between 10-20 perms. You can see the graph below showing OSB and plywood sheathing and their respective permeance. This means that it wouldn't be the synthetic stucco finish that is preventing the wood frame assembly from drying out. Nor would it be the synthetic stucco's fault that the building paper or other type of weather barrier behind the finish failed to keep incidental moisture out. However, It would be the architect's fault if the wall assembly wasn't designed to allow the moisture to get out.
As opposed to knowledge and experience? Intern, please enlighten us as to what is really going on.
"What is really going on," was a bad choice of wording on my part; I do not know what is really going on, anymore than you might. I feel that my speculation and analysis has been fairly straightforward given the things that we do know. In contrast it seems that your's has been largely based on conjecture and fear.
That chart is useless.
In the real world permeability in a wood structure has less to do with plywood sheathing than it does with the joints between panels. The largest source of heat loss in a traditional house is air infiltration, often over 50%. Which is why so much effort has been put into making tighter houses.
Synthetic stucco is applied as a continuous coating and has no leaky joints. This makes it far less permeable overall and explains perfectly why wood sheathed structures without synthetic stucco do not typically display the kind of rot / mold so common with synthetic stucco.
your's has been largely based on conjecture and fear
Or knowledge and experience that you lack. I'll go with that, thanks.
School's over. You're on your own now.
E_I,
There is several types of EIFS or EIFS like synthetic stucco products that uses different types of insulation panel. Also, if it was, it is possible that the foam is not exactly that visible.
HOWEVER, what I see from the plans is something called "Hard Rock"
Even if this was in fact stucco, in wet climate and used over wood, it should be in a rain screen type assembly with drainage.
Such as: http://www.stucoflex.com/waterway.htm
Although I don't know how the assembly would perform when used as an underside of a deck application but there would and should be a drainage element.
Stucco on concrete is probably a non-issue but on wood, it is a problem and known for deterioration of wood in wet climates. So up in Oregon coastal region, you should use a drainable system.
I swore I also saw something noted "Gypcrete" but the legibility of some of the text was hard to read.
As I study this, the gypcrete is also the hardrock noted on the other drawing. With that in mind, gypsum concrete is basically gypsum cement board or basically hard sheetrock except it is poured vs. being in pre-formed sheets.
It isn't waterproof and easily fractures and crack. Prior activities for some time before lead up to water penetration obviously. Remember, it is probably not the first time it had 13 people on the deck and it probably cracked and water infiltrated without anywhere to go as quickly as it came in.
There should have been a drainable assembly specification as far as it appears.
Just my opinion.
I'm leaning to the assembly around the deck wood framing to be gypcrete (gypsum concrete) which is also known as hard rock or cement plaster or stucco. The rest of the building looks to have something that is likely EIFS but the deck isn't using exactly the same stuff as the building's wall assembly.
Miles, again you are confusing the issues and terminology. Permeability has nothing to do with air leakage and heat loss. Permeability is a measure of the ability of water vapor to pass through something ... not air.
The largest source of heat loss in a traditional house is air infiltration, often over 50%. Which is why so much effort has been put into making tighter houses.
A tighter house does not have to be a house that is more or less permeable. Usually in a leaky house things dry out because there is so much air movement. However, with so much heat loss due to air leakage and the effort put toward creating tighter houses you start to run into issues with moisture. The design that worked when it allowed a lot of air movement doesn't when you start plugging the leaks and have a continuous air barrier.
Synthetic stucco is applied as a continuous coating and has no leaky joints. This makes it far less permeable overall and explains perfectly why wood sheathed structures without synthetic stucco do not typically display the kind of rot / mold so common with synthetic stucco.
So your problem with synthetic stucco is that it doesn't leak? I thought the point was to make buildings tighter so that we didn't lose so much heat (over 50%), not the other way around. Again, permeability is not a measure of air leakage. You can make a tight building with regard to air, and still allow a breathable building with regard to water vapor. This is where permeability comes in. My point about the permeability of sheathing materials compared to synthetic stucco is only to illustrate that in an assembly the vapor retarder is the thing with the lowest permeability. For most wood framed construction, the vapor retarder is not the synthetic stucco (if the architect has selected an appropriate manufacturer's product). The synthetic stucco would not be the reason water vapor is trapped in the assembly.
Or knowledge and experience that you lack.
What makes you think I lack knowledge and experience?
Everyday Intern,
If you have moisture permeability then you have air leakage (ie. heat loss). Think back to Physics 101. Water molecules is a compound molecule. Air is atoms which may consist of water molecule but also much smaller molecules.
Think about the geometries of atoms and molecules. A compound molecule like H2O is three atoms of two types with two different atomic mass. Two hydrogen atoms with the smallest atomic mass (which also is likely to be the smallest atom in the Periodic Chart. The other atom type is Oxygen which is a tad larger.
We understand atoms are a compound structure of even smaller components called protons, neutrons and electrons. Assuming protons and neutrons are about the same effective geometry.
Now you can imagine visually that a water molecule is going to be bigger than typical air atoms. So if you have water permeability, the sieve of a environmental control is going to be considerable large holes for something as small as individual atoms like oxygen, nitrogen and hydrogen.
We don't make buildings air tight like we do in space. There is a reason for this. Heat loss is a complex physics matter of thermodynamics and we try to find a balance of air exchange cycles, slowing the transfer of heat exchange. Hot to cold.... cold to hot all the while we also have to manage air quality and not create a Petrie dish inside the wall cavity between interior and exterior sheathing. So not only do we have a physics question but also a biology question.
Just keep making sure you have your science together.
Richard, I don't think your science is wrong regarding atomic mass, geometries, etc. However, building codes don't require air barriers to be 100% effective at stopping air movement, nor are vapor retarders required to be 100% effective at stopping water vapor movement (like you say, we aren't making buildings as tight as we might need to in space). A little bit of molecules moving through a membrane is ok. However, your statement that if you have moisture permeability then you have air leakage is flawed when it comes to buildings and the definitions of air barriers and vapor retarders in the code.
You can control the air movement with an air barrier while still allowing vapor to permeate the air barrier because of the second law of thermodynamics (air moves from high pressure to low pressure; water vapor moves from warm to cold and from more to less). If not, then DuPont figured out a way to break the laws of physics when they created Tyvek (less than 0.004 cfm/sq. ft. @ 1.57 psf of air movement, but yet still allows 54 perms of water vapor transmission ... it's like some sort of scientific miracle!).
This stuff is pretty basic building science and architects need to know it. Toward that purpose, I'm working on a blog post devoted to it and will probably get it posted this weekend if I'm not too busy celebrating America's birthday. Feel free to engage me further on the subject there. Let's not continue to clutter this article's comments with this discussion.
Block this user
Are you sure you want to block this user and hide all related comments throughout the site?
Archinect
This is your first comment on Archinect. Your comment will be visible once approved.