| Author |
Message |
Jerome J. Lazar, RA, CCS, CSI, SCIP
Senior Member
Username: lazarcitec
Post Number: 1117
Registered: 05-2003
| | Posted on Wednesday, July 09, 2014 - 01:59 pm: |    |
The high rise building is 10 years old, located in North Florida, excessive moisture has been detected by measurement of the existing CMU walls which consist of stucco directly applied to CMU, interior construction is gypsum board applied to furring with a 3/4" airspace filled with insulation (granted this no longer meets code).
Assuming the roof, nor fenestrations are the culprits, what could be causing this? Could the Climate Control system be the culprit? And if so how is that determined? |
Wayne Yancey
Senior Member
Username: wayne_yancey
Post Number: 663
Registered: 01-2008
| | Posted on Wednesday, July 09, 2014 - 02:05 pm: | |
Jerome,
Earlier today (Pacific time) I e-mailed you an article by Dr. Joe Lstiburek in this issue.
The e-mail I have is lazarcitec@msn.com
Wayne |
anon (Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, July 09, 2014 - 02:12 pm: | |
this is an easy one.
this is almost certainly a vapor retarder issue. i would bet that there is no vapor retarder on the EXTERIOR of the wall assembly. Which is where it needs to be in a hot, humid climate (FL). For two reasons: hot humid air from the exterior moving into the wall assembly and condensing on cold, air conditioned surfaces, and bulk water that collects in the plaster/CMU after a rain event, then heated by the sun, converting the bulk water to vapor and then moving into the assembly and condensing on cold/air conditioned surfaces.
the solution is to remove the plaster, clean the CMU substrate, and apply a vapor retarder membrane over the CMU (which could be in the form of a bonding agent and provide double duty) and then re-apply the 2-coat plaster.
easy as pie |
Jerome J. Lazar, RA, CCS, CSI, SCIP
Senior Member
Username: lazarcitec
Post Number: 1118
Registered: 05-2003
| | Posted on Wednesday, July 09, 2014 - 02:33 pm: | |
I know of Mr Lstiburek well, since issuing that report (in 2004) Joe has retracted some of his recommendations, apparently he was wrong, you'll have to find a more recent article, there are plenty out there. Don't get me wrong, Ive attended several Joe Lstiburek seminars, he knows I'm an architect, so he always picks on me (Joe's wife is an architect) and I own a good assortment of his books, the way I look at stucco has changed because of Mr. Lstiburek. Back in 2004 Joe was the man, he was touring Florida preaching about building science, but many of his solutions were too pricey for Florida developers and only now, after years of stucco failures statewide are some of his better recommendations being taken seriously.
For example, getting a developer to repaint a high rise building with an elastomeric paint 2 years after construction has completed and the stucco has fully dried is near impossible. Even if agreed to at closing, something else has come up to redefine the use of those funds...or some expert is hired by the Condo Association to resolve other more crucial issues, like noisy trash chutes, please. |
Ronald L. Geren, FCSI, AIA, CCS, CCCA, SCIP
Senior Member
Username: specman
Post Number: 1240
Registered: 03-2003
| | Posted on Wednesday, July 09, 2014 - 02:40 pm: | |
Quote: "...interior construction is gypsum board applied to furring with a 3/4" airspace filled with insulation (granted this no longer meets code)."
Why doesn't this meet code?
Ron Geren, FCSI, AIA, CCS, CCCA, SCIP
www.specsandcodes.com |
Jerome J. Lazar, RA, CCS, CSI, SCIP
Senior Member
Username: lazarcitec
Post Number: 1119
Registered: 05-2003
| | Posted on Wednesday, July 09, 2014 - 03:16 pm: | |
Ron, I've been asked to specify values of 7 to 11 on some recent projects, but I don't know that as fact or as code, if an architect (client) tells me they want R 7 and they are wrong, I still spec R7. I've reached out to one of our MEP engineers to clarify what code currently requires, I will post that answer here. My apologies if I was in error. And to those who think I should not specify something that is wrong, that is not a fight that I usually win, perhaps that should be a new thread, what happens when your client is wrong, do you still spec what they document?
In the case of a higher R Value, its not hurting the project, maybe the developer's marketing is based on better insulation values, so I don't judge it when its better than required, only if its less than required.
When I was given time to prepare specs I would do so by coordinating the specs fully with the drawings and in the process find errors. Unfortunately on some projects my time has been cut by 60% and even less. Architects appreciate my second set of eyes on their drawings, but than they don't follow thru, there is almost no point with some clients trying to correct their work. I can't win all the battlers, lately I barely win a few. |
Jerome J. Lazar, RA, CCS, CSI, SCIP
Senior Member
Username: lazarcitec
Post Number: 1120
Registered: 05-2003
| | Posted on Wednesday, July 09, 2014 - 03:32 pm: | |
From engineer: "Yes R-11 is real……R=7.1 is minimum required to make energy calcs work."
So if urethane is R 5 per inch, how do you get R7.1 in a 3/4 inch air space, we have to specify radiant barriers, not my favorite solution, but it meets code. |
ken hercenberg
Senior Member
Username: khercenberg
Post Number: 798
Registered: 12-2006
| | Posted on Wednesday, July 09, 2014 - 04:08 pm: | |
Jerry, please be careful with a few things here.
1. Radiant barriers require an air space to work and they rarely achieve the stated R-values. See http://www.rimainternational.org/index.php/myths/ and http://energy.gov/energysaver/articles/radiant-barriers for some basics.
2. Keep in mind that most radiant barriers are also vapor retarders. Unlike the "easy as pie" anon commenter above, I don't think introducing a vapor retarder into this assembly will help.
3. I do not know of any way to get an effective R-7 in a 3/4 inch space.
4. If the direct-applied stucco didn't work the first time I have to question if it will work a second time if the cause of failure has not been determined and fixed. Yes, it could be coming from any number of sources including the HVAC system, the roof, the windows, the humidity in the air, etc. Drying in an drying out are still your best options as Dr. Joe might say.
It sounds like a water-managed system may be your best bet. Perhaps MTI can offer some options such as their perforated cavity products - http://www.mtidry.com/products/rainscreen_products.php I'm suggesting the perforated product in the hopes of avoiding the creation of a vapor retarder. I'd consider fastening this to the face of the CMU, applying lathe, and then apply the stucco. Without having the benefit of direct application to the CMU you'll need to watch your joint spacing and materials but this will give you a continuous drainage plane if that's what you're trying to achieve. The EIFS drainage system may give you both your R-value and water-management solutions while also putting your insulation in the right place in relationship to the rest of the wall assembly. Not my first choice, but it may be the most benign option.
As to your original question, I'd probably prefer to daylight/flash at each floor level and change in plane. |
Jerome J. Lazar, RA, CCS, CSI, SCIP
Senior Member
Username: lazarcitec
Post Number: 1121
Registered: 05-2003
| | Posted on Wednesday, July 09, 2014 - 04:25 pm: | |
Ken, thanks for your input, on most of my projects the architect has increased their wall assembly thickness to allow for a 1-1/2 inch air space, local building departments are accepting Fi Foil's VR Plus Shield with and R Value of 7.1 which is a very popular low cost solution. I prefer extruded polystyrene.
Anon did not offer anything new, his or her solution is already on the building. Using the wrong bonding agent has been a problem in FL that may be a cause for delamination, as the bonding agent becomes a bondbreaker.
Ok Ken please explain what you mean by daylight/flash? |
ken hercenberg
Senior Member
Username: khercenberg
Post Number: 799
Registered: 12-2006
| | Posted on Wednesday, July 09, 2014 - 04:39 pm: | |
Just another way of addressing the weepage. It's not a true cavity so I see it as daylighting the drainage plane more than weeping. Just one of my many quirks I guess.
Bonding agents can be a headache, especially if you're using acrylics since they can re-emulsify when water gets into the system. You're limited since epoxy bonding agents can form a vapor retarder plane. Not sure if there is a good option here; probably just go with whatever the stucco manufacturer is selling and pray a lot. Another issue with bonding may be if coatings such as silanes or siloxanes are being applied to the CMU before the stucco is applied. By definition these will prevent a good bond from occurring. |
Alan Mays, AIA
Senior Member
Username: amays
Post Number: 199
Registered: 02-2003
| | Posted on Wednesday, July 09, 2014 - 04:48 pm: | |
Jerome, I suggest (if it hasn't already been done) that a forensic consultant be introduced. There are way too many possible sources and anyone is just guessing (educated of course) here. The source of the water needs to be determined before the appropriate fix can be suggested. Is the water coming in from the inside? Condensation? Is the building under negative pressure (HVAC) and drawing the moisture into it? Is it the lack of a weather barrier and water is getting in through cracks at the mortar joints? Where is the dew point in relation to the wall? Is the problem the roof or the parapet? I agree with Ken, a water management system may need to be used, but that will not solve the situation if the source is on the inside. EIFS can be a problem if the building is built right on the property line and the added thickness may push the building to be over the property line. |
anon (Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, July 09, 2014 - 05:29 pm: | |
I saw nothing in the original post about a vapor retarder in the assembly. If there is no way to prevent vapor from migrating from the exterior to the interior, and the building is air conditioned to a lower temperature than the outdoor temp, then you absolutely will get condensation due to vapor migration through the assembly from the exterior. All this is in Lstiburek's books.
And reverse vapor drive, sun heating rain soaked plaster, is also a mechanism that drives moisture, in the form of vapor, into the assembly - again from the exterior.
Where in the assembly is there a vapor retarder? And what is it? |
Phil Kabza
Senior Member
Username: phil_kabza
Post Number: 544
Registered: 12-2002
| | Posted on Saturday, July 12, 2014 - 10:25 am: | |
At 10 years old, the coating system on the stucco, whatever it is, is likely pretty well weathered. The stucco no doubt is extensively microcracked if not full of hairline cracks. Given the extensive wind driven rains in Florida, it's no wonder there's lots of moisture in the CMU. The major source may be water infiltration, rather than water vapor migration. If nothing else, apply a proper re-coating system consisting of an elastomeric that has reasonable water vapor permeance. You don't mention water on the interior or presence of mold within the walls. A quality maintenance re-coating could allow the moisture in the CMU to return to normal, maintainable level. |
Jerome J. Lazar, RA, CCS, CSI, SCIP
Senior Member
Username: lazarcitec
Post Number: 1129
Registered: 05-2003
| | Posted on Saturday, July 12, 2014 - 02:06 pm: | |
Phil, the developer has told the architect little more than what I explained here, I agree the developer should have repainted 3 years after the building was occupied with an elastomeric, but the job had serious problems with the original contractor who defaulted and a surety took over to finish construction. I too wonder about mold, but until they ask, I don't. |
|
4specs.com Home Page