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Aaron Levinson Posted: Jul 14, 2011 02:24 PM	High humidity in attic on hotter days in Portland, OR I'm asking this question in this forum since other similar questions have been asked in the past here. In 2008, I had open-cell spray foam (Sealection Agribalance) sprayed on the underside of the roof of my home. There was already existing fiberglass insulation on the floor of the attic that was not removed, although I raked it back the best I could so that the contractor could spray the gables properly (or so I thought at the time). The job was to spray the underside of the roof completely, including the pre-existing vents in the gables (which were taped over prior to spraying). The spray foam has mostly been working fine, but on relatively hot days (that is, 85-95 degrees) in the summer, it gets quite hot in the attic, and in addition, it gets extremely humid. I haven't taken any readings, but when it is humid like this, after just spending 30 seconds in the attic, my clothes feel drenched. I don't feel any humidity in the rest of the house--just the attic. This humidity issue does not occur during the rest of the year--it only occurs on the few hot days during the summer that we have here in Portland. I should also point out that it is typically not humid outside in Portland during the summer. In addition, the humidity problem occurs whether or not I have the AC on, and in fact, the last time it occurred, the AC was not on and had not been on for a couple of weeks. A couple of months ago, it was suggested to me that the problem might be caused (or at least exacerbated) by the pre-existing fiberglass insulation. And it was pointed out to me that it probably wasn't helping anything to have it there. In addition, on closer investigation, it appeared that the gables weren't completely sprayed due to the preexisting insulation being in the way in places and some other obstructions. So, I had the fiberglass insulation vacuumed out, although there is still some remaining that was embedded in the foam when it was sprayed. The humidity issue on hot days did not go away, however. I should also point out that on these hot days, I can also smell the spray foam. During the entire year, there is always a faint odor in the attic itself, but on the hot days, the smell permeates through to the second floor (the home has two floors). The fact that the attic is hotter than the rest of the home on hot days seems fairly normal to me, but the humidity issue does not. Any ideas on what might be causing this problem? Thanks, Aaron
John Shockney Posted: Jul 14, 2011 03:02 PM	? how thick was the foam sprayed? Airpro
Aaron Levinson Posted: Jul 14, 2011 03:54 PM	5.5 inches thick Aaron
jimcoler I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs. I've expanded my knowledge into t Posted: Jul 14, 2011 10:26 PM	So, where is the moisture coming from? I recently went into an attic which we sprayed the underside of the roof and it was 85F and 85-90%RH. The customer called and questioned if they had a roof leak or not. I came out with the IR camera and found that it was hot and humid, but then headed for the basement. As I was asking the customer about the basement, she said it had been flooded the past couple of weeks. Answer number 1! Then I went down in the basement and she said that they have a drain coming out of their fireplace into the sump pump. Answer #2! Then I saw three racks of clothes drying in the basement with wet cloths on them. Answer #3! So, the root of the problem was the activities of the occupant, not the building itself! So, what's under the basement floor/Slab on grade floor? What about the basement walls? What about the downspouts? How far away from the house DOWNHILL do the run? I assume there are gutters?
Posted: Jul 14, 2011 10:41 PM	..one time... at band camp,,, ask mason knowles :)~
mason Posted: Jul 15, 2011 01:17 PM	The fiberglass on the floor of the attic would insulate the space between the inhabited space and the attic, so I would expect the attic space to be warmer in summer and cooler in winter than if the fiberglass was not there. As for the humidity issue. First you need to determine where the moisture is coming from. Are there areas on the underside of the roof deck that are not sealed allowing hot moist air in? Or is it moisture from within the inhabited space being dumped in the attic. Make sure your mechanical vents from kitchens, bathrooms, laundry rooms etc. are venting to the outside of the house and not into your attic. Check the duct work to make sure it is sealed well. Both items can dump massive amounts of moisture into your attic space. check the roof deck and kneewalls to make sure the foam is uniformily sprayed to a sufficient thickness to insulate and provide a good air seal. Check for voids behind the sprayfoam. Also, your HVAC equipment may be over-engineered for your sprayfoamed house. Frequently the foam provides energy efficiency so that existing air conditioners don't run long enough to take out moisture in the air. Combine that with the extra air sealing properties of the foam, it is not unusual for moisture to build up in the house. I had to switch out my AC unit after my house was spray foamed. I went from a 2 1/2 ton unit to a 2 ton unit and also went with a multi stage unit. After switching out the AC, my humidity levels dropped 10% in my house in the summer. You might also get help with the humidity levels by adding an ERV of HRV. These can help condition air so that the right humidity is maintained. As for the odor, take some samples of the foam and see if the odor is coming from the foam. It could be slightly off ratio or installed over a damp substrate causing a slightly B rich material.
John Shockney Posted: Jul 23, 2011 04:21 AM	I know that this is Ask Mason, but I think we have seen this before here at sprayfoammagazine.com Hi Aaron, First of all without accurate temp and humidity it is hard to say if you have a problem or not, the human body is not a good thermometer or good at measuring humidity. The human body can only determine about 5deg of temp diff and even less when it comes to humidity levels. Second higher humidity levels in a house are not always a bad thing. Moist air holds more heat and can help to maintain temps at the comfort level desired. High humidity becomes a problem when it affects the comfort in the living portion of the house or when the warm moist air can find a cold surface where it will condensate back into water causing mold and or rot. So by just going into the attic for 30 seconds is not a good measurement. Personally I don’t think 5.5inches of open cell is enough. The big “D” has an ICC ESS report that basically says that 3.5inches in the walls and 5.5inches under the roof is enough open cell foam insulation for up to zone 5 or 6 and they use this to promote their products and compete directly with the fiberglass and cellulose guys while keeping their profit margins high. This is why when you told the manufacture of the foam I asked how thick. So let’s look at this from a heat loss/heat gain calculation standpoint: 5.5 inches of open cell foam with an R-value of 3.8 to 4 per inch gives you roughly R-22 that is a U-value of 0.04545 BTUs/sqft/hour/deg F temp diff Now consider that you are trying to keep the inside of the house at 70degs with outdoor temps at 90+ and adding the heat from solar radiation your shingles can reach 140deg or more. That gives you a temp diff of 70deg. Just for G P we’ll figure that you have 2,000 square feet of roof. So if we do the calculations 0.04545 x 2,000 x 70 = 6,363btus of heat gain into the house/attic every hour. Now if we increase the R-value to R-40 the U-value will be 0.025 so the heat gain will be 0.025 x 2000 x 70 = 3,500btus per hour, at R-50 = 2,800btus per hour, R-60 = 2,333btus per hour As you can see after about the R-40 point the gains become much less cost effective and I would also point out that the air space the attic itself provides is also an insulator and provides additional thermal mass that does help keep the living space comfortable which is the goal. Another choice would be to reduce the heat from solar gain by using the most effective radiant barrier there is: change the roof color to as close to white as possible this can be the most cost effective way to reduce heat gain. Airpro
jimcoler I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs. I've expanded my knowledge into t Posted: Jul 24, 2011 02:08 PM	OK, Now I know we;ve already gone over this in the past, but I guess we need to go over it again. 6" of OC spray foam is enough insulation for the underside of the roof. This is based on a study put out by SPFA in 2006. The cost effectiveness of foam is about 95% or over in about 5" and you gain very little benefit from the added "R-value"! NOw that we've brought up R-value, let's see how it's measured. It's measred in a guarded hot box test with 75F on one side of the insulation and 50F on the other side with no wind conditions. This happens in real life on about 3 days of the year! That's less than 1% of the time that it's being tested for. Now, the situation that airpro has described is partially true in that the roof temp will reach 140F. But the R-value and calculations are based on false testing and measurements. When you put garbage in, you get garbage out - or something that smells much worse -can we say partial compost! So, 6" of open cell foam sould be fine even in climate zones 5 and 6. So, airpro's comments on the accurate temps and RH are true. I would suggest getting a temp ad RH meter and put it up there to determine the measured Temp and RH. You can also track the temp/RH periodically and see how much it is effected. Mason's comment about the fiberglass on the attic floor is partially true. It wil work a slight bit, but not that great. We've found that fiberglass in the attic floor typically results in abot a 10F temperature difference between the inside of the house and the attic space. This isn't as great as many lead you to believe!
Chicago Spray Foam Posted: Jul 24, 2011 07:50 PM	Just to clarify, are we talking about leaving fiberglass insulation on the attic floor in addition to the foamed underside of the roof?
steven argus Posted: Jul 25, 2011 01:08 PM	To quote Jim, "So, 6" of open cell foam sould be fine even in climate zones 5 and 6." Key word here is "should" Jim, how would you like to hear, "You should be paid" Not good enough.
John Shockney Posted: Jul 26, 2011 02:16 AM	Ok Jim, First of all I will agree that 6 inches of open cell on the underside of the roof will work in zone 5 or 6 but I don’t think it will give my customers the energy savings that they are looking for. As to your statement about garbage in garbage out the numbers that I used were to compare different thicknesses of open cell spray foam based on the R-value provided by the manufactures at the same temps that you described in the hot box test. These calculations are based in physics, kinetic theory, how energy in the form of heat moves through a solid they are not garbage, they are how HVAC professionals size the heating and air conditioning equipment for a building. As you have brought up the Guarded Hot Box test that is used as the insulation industry standard as mandated by the Federal Trade Admin and the reason that the cold plate side is not set below 50deg is that it is set up in a lab to test fiberglass and other insulation materials that use trapped air as its primary insulator, if they lower the cold plate temp below 45deg condensation forms on the cold plate wetting the insulation invalidating the test as the R-value goes down to almost zero. Corbond and others like Oak Ridge Labs have done testing at much colder temps by eliminating the condensation problem with the use of dry nitrogen in the test sample. It is in these tests that with hot plate temps of 75 and cold plate temps as low as -20deg we find that R-19 spray foam drops very little R-value and closed cell drops the least amount (every insulation’s R-value drops some at those temps), but that R-19 fiberglass batt goes down below R-10. This is why you can tell your customer that R- 19 of spray foam will perform like R-35 to R-40 of fiberglass and this is the biggest problem with the rating system it is set up to make fiberglass look as good as foam but doesn’t show what happens at extreme temps. If R-values aren’t important then next you will tell me that BTUs aren’t a scientific measurement of heat. Airpro
SprayFoamSupply.com Posted: Jul 26, 2011 06:55 AM	Is the 2006 SPFA study that you are refering to the article, "Determining Insulation Thickness" by Roger Morrison? If so, that article referes to closed cell foam, open cell is not mentioned. If not, can you post a link to the study? George
mason Posted: Jul 26, 2011 08:41 AM	I have a copy of Roger's paper that was presented at Sprayfoam 2006 conference in Tucson. I asked Roger to make that presentation to provide some quantifiable data to assist sprayfoam contractors in determining how much foam to install on various projects. George is correct the foam used in the calculations are closed cell foams. However, R values are listed in the tables next to the thickness of the foam. So 6 inches of foam in the paper equals R 40.8. These calculations are subject to change depending on the delta t of the specific project. You would require more R value in extreme climates than what is shown in the paper. For example, my father specialized in cold storage applications from the late 50s to the mid 80s. We found that the most practical thickness of closed cell sprayfoam for cold storage projects was as follows: 20-30 degrees F 3-3.5 inches 10-20 degrees F 4.0 inches 0-10 degrees F 4.5 inches -15-0 degrees F 5.0 inches -20-30 degrees f 6.0 inches -30--40 degrees F 7.0 inches These freezers were located in the Southwest part of the country, (Houston, Louisiana, west Texas, etc.) So, the delta T was considerable on hot days. (95 degrees F outside, -10 degrees inside) The total thickess required for residential applications in cold and hot climates would be correspondingly less since the delta T is much less. (example 10 degrees outside, 70) Roger lists 3 other requirements to determine insulation thickness: code requirements (typically the higher of the 4) to prevent condensation maximum practical thickness (how much can you really install in a given area) SPFA also has performed research on sprayfoam, (open and closed cell) applications to wall assemblies and attic assemblies. Both open and closed cell foams demonstrate energy efficiencies 20 to 40% greater than equal amounts of R value from fiberglass insulated assemblies. For example in the attic study, 5.5 inches of open cell foam installed to the underside of the roof deck performed the equivalent of R 38 of blown in fiberglass installed to the floor of the attic. In this test (conducted at Oakridge National Labs), the attic assemblies were sealed, so the only difference in the performance of the products was the convective currents allowed in the fiberglass insulated assembly. In the wall performance tests, (conducted at Architectural Testing Inc.) air was introduced into the assemblies and the fiberglass assemblies performed worse relative to the sprayfoam assemblies than in the attic tests.
John Shockney Posted: Jul 26, 2011 01:57 PM	Well from what Mason says it basically confirms what I have been saying and it looks like Jim is all wet. As to the smell issue I have never sprayed the Sealation product but I have never had an odor complaint either, has anyone else seen this video Airpro
Posted: Jul 26, 2011 02:01 PM	ap,,,when he lays the garbage in garbage out line he is referring to our computer modeling programs,,,like the WUFI,,or HAM or,,, see those programs pull the numbers outta their butt too,,eh mason,,,
John Shockney Posted: Jul 26, 2011 08:47 PM	dude, I remember during the Apolo program when computers had less power than a digital watch to day that the term garbage in garbage out was first used. And we were using slide rules in school chem and physics. I know that most spray foamers are ex~roofers but need to understand something about how heat moves to best advise your customers. Airpro
jimcoler I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs. I've expanded my knowledge into t Posted: Jul 26, 2011 08:56 PM	airpro, All wet? What are you talking about. As I read Mason's statement, it seemed to support what I was saying about 6" of open cell foam being enough and even equating that to an R-38 fiberglass blown in - in performance. As to your questin about the garbage in-garbage out, I was referring to you using the R-value! The issue with the R-value is that fiberglass can't be tested below 45F without condensation occurring -as you stated. Then there is the failure of the product! It can't be used at 45F temperatures or below! There is the failure of the FTC in protecting us (the public) with lobby actions promoted by the fiberglass industry! If the FTC is promoting the R-value rule and promoting fiberglass, then there is something rotten in Denmark! Mason, the instalnce you're referring to is for cold storage and that has a continuous vapor drive condition. We're talking about residential applications and the Delta T is much less as you stated. There is also the temperature changes in the days and nights that can help stabilize the vapor drive. I don't think it's fair to bring a cold cooler into the equation when we have diferent vapor drive dynamics. dude- you are correct about the WUFI andother models b ut it's also true about the R-value! That's what I was referring to being garbage in-garbage out. The R-value isn't fair and it's garbage. So, what comes out when you use it in an equation? Garbage!?! Guiness - You are correct in that statement. I should have said that it is fine and perfectly acceptable to our customers over the past 8 years which is what I've been doing. As far as the energy savings, I don't see much of a difference between 6" and 8" or 10" of foam. We've done it but they haven't seen a major benefit over and above from the 6" of open cell foam.
John Shockney Posted: Jul 27, 2011 01:08 AM	Jim, I had said the same thing 5.5-6 inches of open cell foam is equal to R-38 of fiberglass but that is because the R-38 of fiberglass will only perform at around R-19 when the outside temp drops below 20degs. And with today’s higher energy costs that is just not enough you need an R-value that will test at R-35 to 40 when the temp outside drops to 0deg or hits a high of 150+, not only considering today’s energy cost but higher future costs. You had also said that 6inches of open cell would stop 95% of the energy loss according to an SPFA paper and Mason corrected that it was 6inches of closed cell with an R-value of 40 and that is where I had said the real point where cost verses energy saving dropped off and that this was based in the pure science of Math and the formulas used to compare insulation’s resistance to heat flow. If all testing for R-value is garbage then where does that leave us when we are promoting the higher R-value that our products can provide? There has been testing for fiberglass insulation that has been done down to minis 20deg or colder that was done by removing the moisture from the sample with dry nitrogen, most of this testing has shown a drop of over 50% from its rated R-value. It is at these extreme temps that our products shine when compared to fiberglass what we need is not a new way to rate insulation performance (R-value) but require the testing and labeling show what the R-value is at the different temps the insulation is expected to be used at. And yes I do know that the movement of heat In and out of a building isn’t just limited to the conduction (R-value) through the walls and roof, but also due to air movement and that spray foam is the best solution to an air leaky house. ASHRAE has long known that R-value testing was faulty and recommended using an R-value of 7 when doing heat loss calculations for a wall filled with R-19 fiberglass. This is why they are the driving force to push required R=values higher and the adoption of the new IEC, it is because of the faulty testing standard that we may soon see R-60+ attic insulation required and R-30 walls. So Jim keep your blinders on and keep selling that 6 inches of open cell on the underside of the roof is all you will ever need, I will keep giving my customers the best info I can and let them make the decision that is best for them. Airpro
steven argus Posted: Jul 27, 2011 09:26 AM	Jimbo, let's be realistic here. Selling customers 6" of OC is really just an easy way to beat the competition. I'm guilty of it myself. I agree, that 6' of OC will beat the performance of R38 fiberjunk, but let's not sugar cote it. 6" of OC in the roof and 3" of OC in the walls puts your price down close to fiberjunk. It also is way below the other foam guy. This "good enough" approch will bite you in the azz eventually. R19 - R21 in the roof is not code compliant in zones 4 - 5. It may not be fair to us foam guys, but we still have to meet code.
John Shockney Posted: Jul 27, 2011 10:48 AM	Actually Jim, Almost everything that you have said supports my calculations and what I have stated supports your statements. The only thing we differ on is our conclusions. All customers want to get the best insulation for their money and are looking for return on investment and sometimes they can only afford that 6 inches or the attic they are converting to living space ceiling is framed with 2x6s or less and they just don’t have the money for closed cell foam. So yes I too have sprayed that 5.5 inches of open cell on the underside of the roof and it is better than anything that can be done with fiberglass, but I don’t tell customers that the R-19 it provides is the end all solution, it like most things in construction is a compromise. Heck heating systems and ductwork should always be installed in the floor and the air conditioning system and its ductwork should be installed in the ceiling, and both systems should be inside the building envelope how many times have you seen that done!!! So keep spraying Jim just think about spraying a little thicker I think your customers will be the better for it. Airpro