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Posted: Dec 20, 2009 09:42 PM	Flash -n- batt Mason, what is your opinion on a flash and batt job using 1.2#, up to an inch? We're required to have a vapor retarder on the inside of the wall in our area. The 1 inch of 1.2# would be considered "semi-permeable" and the fiberjunk guys follow us and install a 5 1/2" batt with kraft facing. (vapor retarder) I know the 1 inch of 1.2# is not considered an "air barrier", but common sense say's it will stop the wind. Thanks.
mason Posted: Dec 21, 2009 08:21 AM	The flash and batt system as originally conceived is a closed cell SPF covered by either fiberglass or cellulose insulation. The concept is that the closed cell foam would provide an air barrier and condensation control if installed in sufficient thickness. I have never heard of using open cell foam in this type of concept. I am not sure what the value would be. The permeance of open cell froam is pretty high at one inch thickness and I have not seen any air infiltration tests conducted on open cell foam at that thin of an applicaton either. I don't see the value in installing one inch of open cell foam followed by fiberglass. Why not just use the open cell foam to full thickness? Then you know the wall is sealed properly against air infiltration and has the required R value. Note: In colder climates you would need to add a vapor retarder to the warm side (in winter) of the open cell sprayfoam insulation but not in mixed or warm climates.
CHARLES MAURO Posted: Jan 21, 2010 07:42 PM	Hello Mason, It's been my understanding that a minimum 2" application of closed cell SPF would give you the neccessary air barrier and moisture/vapor retarder. Is this correct, or can I reduce the thickness to 1" as some of my competitors have claimed? Thanks
Michael Fusco Posted: Jan 21, 2010 08:25 PM	You know guys, we keep wanting to get thinner and thinner....you better start worrying about reversion if you start getting close to 3/4", or even an inch unless you think your that good! Heard today that Owens Corning is starting to see cracked foam from spraying too thin in their hybrid offering.
mason Posted: Jan 22, 2010 02:39 PM	I personally like to provide the thickness of closed cell foam that will provide the vapor retarder properties in the assembly without relying on a separate vapor retarder element over the fiberglass. 2 inches is typically the thickness most folks recommend in northern climates. Although a few like to install 2.5-3 inches in the more severe climates such as Montanna and Northern Wisconsin But if you can provide a vapor retarder element over the fiberglass that is installed properly (no tears, gaps, holes, etc) then the lower thickness of closed cell foam (1 inch) would work. Some folks are selling and marketing hybrid systems (flash and batt) in northern climates with 3/4 to 1 inch of foam followed by fiberglass that has a vapor retarder facing. But, I am fairly conservative on this issue, knowing how often the fiberglass and vapor retarder is not installed properly.
andy buff Posted: Jan 23, 2010 05:00 PM	so if youre doin a flash n batt with an 1.5 inches of closed cell do you use unfaced fiberglass? and guys like ed using open cell up to an inch hows does that work from a performance stand point?
Posted: Jan 23, 2010 09:44 PM	reflections from the cornfield... cold climate zone 5 here,,, this criteria has to be declared first and foremost,,,relevant to vapor retarding membrane... so,,,since closed cell foam is a vb retarding membrane at ~1.5 - 2" pending on whose literature you are reading (and from when,,lol)you could be putting a vb retarding membrane on the cold side of the wall with said application..not a good situation in my zone 5... now i expect the argument of "modeling will show that said app is good,,,will not show condensation"...well,,,lower the temp on the outside..or mess with the humidity levels a little in the modeling and you will see condensation at these depths eventually,,,(it was friggin 25 below zero for 2.5 weeks here recently,, model that,,every non-full-foam wall was condensating like a ******...out of sight out of mind...oh yeah and did any one crawl up in an attic in those temps..i did,,but me boo-coo-crazy-gi) anyway,,back to flash and batt... first: a flash and batt system will not afford the end user much if any increase in performance of the wall system...what it does afford is the filterglass or smellulose doesnt loose up to 1/3 of its labled rvalue under the crappy conditons described above..conditions when we need insulation the most...you still have an r19 filterglass wall system,,,but you do have a better air barrier so it will work " little better" under adverse conditions,,but it does little for convection or radiation (read about the 3 modes of transfer of heat for a good time) so,,me personally,,,i shoot 3/4-1" cc BE to create a better air barrier..to help controll the uncontrolled air movement into or out of the wall cavity...i do not want my applicators to get out beyond 1"...i use 1.5" as a vapor retarding membrane,,,customers percieve this as cheap earl,,till i educate them,,and if they know poop-from applebutter about vb's they soon see my rationale...you can not have steak on a hamburger budget...cheap begets cheap...and filterglass is damn cheap... so i recommend a vapor retarding membrane(paint or plastic,,nuther topic eh mason?) on the warm side of the wall in my 3/4-1" applications...any moisture vapor that violates said membrane will dry to the outside as it should whether the foam is in the cavity or not,,it is not a vb membrane at these depths... and ed,,any high pressure spray applied foam open or closed cell at an inch or so is a quite nice air barrier,,,much more effective than the tyvek and tape...THIS IS NOT TRUE OF THE PREEXPANDED FROTH PAK FOAM SYSTEMS MANY ARE SELLING AS A AIR BARRIER..IT IS ADDITIONAL RVALUE BUT IT IS PRE EXPANDED SWELLING AT BEST INTO THE WALL CAVITY BUT NOT INTO THE MINUTE CRACKS AND CREVISES INHERENT TO THE BUILDING PROCESS,,THE CRACKS THAT MOVE AIR,,PARTICULARLY WHEN THE STRUCTURE IS PRESSURIZED WITH HEATING OR COOLING EQUIPMENT.. and the additional 1.5 R per inch of splatter foam is not worth the cost,,do the math....may as well drop in some board stock,,caulk the seams and cover with filterglass.. oh yeah,,,and resonable hvac equip...erv/hrv,, will manage moisture vapor better than kraft, or poly or paint,,an my builders use it in there homes foam or no foam...build tight,,,ventilate right,,manage the indoor air quality for the benifit of occupants and the structure as well i think it goes.... now can i do an air seal with OC..yep..but the filterglass crew hates workin over it due to its more irregular profile as its depth of application is less consistent due to it highly expansive nature,,but indeed it can be done... but my builder will go with the cc be over the oc be once they consider the beauty of the cc app oh double yeah...the cracks are due to either thermal shock,, or bad chemistry,,,i'd do a 1/2" Building envelope,,and could...if there was any money there....but it just dont compute... hope this helps... 'dude ps wufi modeling and HAM modeling here as well
mason Posted: Jan 25, 2010 08:54 AM	You could use unfaced fiberglass with the closed cell foam. A vapor retarder faced fiberglass doesn't have a functional purpose if the closed cell SPF is thick enough to prevent condensation. As for what to use when you do have to use a vapor retarder over open cell, my preference is to use a paint or coating that can double as a thermal or ignition barrier (in attics or open cavities.) In walls that have drywall you can use sheet plastic or a paint or coating. But if using the plastic be sure it is installed correctly, no holes,gaps, tears, etc.
John Shockney Posted: Jan 25, 2010 10:51 AM	Ok my question is what is the economical (and R-value) advantage (if any) of the flash and batt system if you can spray 3 ½ to 4 inches of open cell for the same cost as 1inch of closed cell. I haven’t found any advantage so please explain. Please note that I do think that closed cell is better but open cell is still better than fiberglass in any application and it is up to what the customer wants and can afford. Thanks John Airpro
Posted: Jan 26, 2010 05:24 AM	airpro.. you are deadon.. i can apply and R21 oc in a 2x6 for about the same price as a BE with r19 glass over,,, a SUPERIOR wall system...air barrier..a wall system that doesnt loose performance in adverse conditions(confective looping,,even with foam BE),,ect.. so im wiff you on this one... what is goin on here,,the fiberglass folks advertise they "now do spray foam",,when they are splatterin the wall with the froth pack system (1/2" or so,,and now they have heated hose..woohoo,,lol) and coverin it with glass as fast as they can so it is out of sight and out of mind..they sell hard against open cell systems,,and sell harder against the "just way to expensive cc r19 system",,, with proper education the discerning builder/homeowner will see the way,,problem here is you end up sellin against cheap..they probably came to you first,,got knocked out by the number for foam and went searchin for cheap..and they got it....follow up is tantamount to the education process,,dispell the misinformation,,show the added value of your system...im wiff you john,, now then,,, if you have a vapor retartding membrane on the outside of the wall cavity,,,and you use a vapor retarding membrane on the otherside,,,either kraft or poly you have now created the potential for any moisture vapor which violates the vb membrane(remember there is no perfect vb membrane in typical construction)to be "trapped" in the wall cavity,,unable to "dry" back to the outside or inside,,what ever the case may be...not a good thing,,,tis real,,, now i am reading(and modeling shows) that 12mils of most wall cladding paints(the perty stuff on the interior,,the stuff the lady of the house picked out) affords a pretty good VB retarding membrane...and a few of the folks who used to claim "no vb membrane needed" over their oc foam but indeed ended up with failures in the world use this data now to substantiate their claims...(they use to say this due to the superior air barrier created by the foam app,,and the largest percentage of moisture is xported by gross air movement),,but it didnt address diffusion..physics is physics...which is why i keep my cc BE app at 3/4-1" here in zone 5 cornfield... (john,,4" @3.6r/inch = a 14.4 r in a 2x6 wall,,,not even close to r19 needed for energy audit/rebates and the MINIMUM recommended rvalue in my cold climate area..it is not enough and will not afford the customer "up to 40% savings in energy bills",,equilibrium maybe but not increased performance and the builder will percieve this as "the foam really isnt adding a performance boost to my buildings",,they are heating and cooling for the same money...so why spend the money and go thru the other things needed for the system to work right..) you cant deliver 30% less and expect 30% more,, think about it... 'dude i plugged the numbers into the puker what it said made me stupider burma shave
Ivan Pauliuchenka Posted: Jan 27, 2010 12:43 PM	Check this out - good animation from Icynene on how it works. http://www.icynene.com/moisture-transfer-animation/
SprayFoamSupply.com Posted: Jan 27, 2010 07:19 PM	Who is going to be held liable for failures in the typical flash and batt system where 1" or less of cc is used? Icynene animation isn't bad, but how come they show in summer moisture condenses on the backside of the drywall on the vapor retarder with the flash and batt system, but with the icynene system the moisture passes through the VB on the VB paint? George
Posted: Jan 28, 2010 04:08 AM	typical icy add,,, damn perty too,,guess its gotta be true.. shall we mention energy design update from a few years back??? im guessn not,,me neither... eeba references the interior wall paint as a potential vb membrane,,sealer, primer, paint,,out at 12mils or so,, (more manipulation of data to make it say what you need it to say,,,waytypical for these fine folks) the icy dealers arent sprayin the foam and the studs behind the rock with a vb retarding paint round here,,,are they supposed to be to complete the icy OC wall system?? is this icy required??? why isnt this listed in their icc-es report??should it be?? george,,modeling shows condensation potential in a BE system at 2" as well once it gets where we are out here this morning,,0 degrees and a 15mph wind,,,now you have a vb retarding membrane that will not allow this excess moisture to dry to the outside,,it now must/can only be dryed back to the interior,,by friggin difussion,,go figure..god luv the mechanical ventilation that better be incorporated into the system..wait a second,,we were goin for cheap werent we???damn EVERY wall,,with or with out a foam AIR BARRIER is frosting this morning,,the conditions are perfect for it...you just cant see it,,, george,,remember the BE with dense pack filterglass,,net and blown at 3-4lb/cu ft system installed a ways back that then had the rockers and mudders and tapers in there with their torpedos and lbwhites and all the excess moisture by the finishing process and cold cold temps and the water runnin out of the walls cause the filterglass folks didnt use a vb membrane under the drywall..rofl...i didnt forget.. the BE system only affords the performance boost of a better AIR BARRIER...keepin the filterglass from loosing 1/3 of its labled rvalue when the wind blows on the wall,,,thats all folks,,,it is not a performance boost,,,cheap is cheap..you still have a filterglass wall system,,plain and simple,, and yes icy folks,,i too believe a complete OC wall system far exceeds this BE system..and i can apply my OC system for the same money as the BE with glassover with poly vb,,,but the glass folks sell the BE hard to maintain their market share,,is about the education process and frequently the chance for rebuttal to dispell the myths and falsetruths,,but most often that opprtunity dont happen,,insulation is boreing and the color of the walls or the type of tile takes much more priority,..lol doning long undies so we can spray today...
Posted: Jan 28, 2010 09:10 PM	George- Liability for the vapor retarder is on the fiberjunk guys. We install 1.2# open cell and let the other guys install the filterjunk w/ craft facing. Foam board has been used on the outside of the house for years. As long as we install a semi-permeable air seal we're ok. Nothing in the code book that says we can't do it. Dude- I agree with what you say, and I'm just a squirrel trying to get a nut just like everybody elese. I'f the fiberglass contractor want's to pay me $1.00/SF to spray an inch of OC, I'm gonna do it. Everybody's happy. We can't spray R21 OC cheaper than a flash and batt, so a flash is the next best thing and we're spraying and making money. Never heard of a "burma shave" Please explain. Is this some sort of new foam planer? Ed
Posted: Jan 29, 2010 04:49 AM	ed,,,small 'dude if you please,,,im just a little turd.... anyway burma shave was a brushless shaving cream from way back,,like long ago,,when olger and mac-aroni were just startin shavin,,,, they were known for their creative roadsign advertising that were short phrases on a multiple roadsigns,,usually 3-4 words or less(so you could read em),,with the next sign down the road about 1/4 mile,,with successive signs till the phrase was complete...do a wiki and read about it,,,funny as heck,,, there used to be a couple still in existence up by swaledale iowa,,,but its been a while since i been up there.... anyone still see these in their area..would luv digital pix....yes im weird... $1 a brd frt for OC,,you go girl!!!!damn,,, i shoot my BE CC for $1.10,,this includes headers topped,,open corners filled, and other details that keep us keepin the trigger pulled... i want to do truss heels and box and rim joists with this app...but only bid those at 3-4" application,,blocked and vented by the filterglass folks,,get in,,get out,,and get your check... (the splatter foam folks get work sayin $1 brd ft...and it is usualy a 1/2" or so "skim coat" as they so "eloquently" call it...do their best to damage the applications benifits..lol good luck 'dude
Posted: Jan 31, 2010 10:14 AM	"i'm just a little turd.."??? Come on, don't sell yourself short. I'm a big fan of yours. You tell it like it is. You seem to have alot of real world experience and you have alot to say. Keep up the good work. Sorry to get off subject.
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: Feb 01, 2010 09:57 AM	While we're on the topic, I think Flash-n-Batt is totally false. The building science for this can be confusing. Let's start with moisture vapor. It's everywhere and wants to condense on things which are colder. This is what happens when we drink our beverage on a hot summer day. The warm moist air condenses on the outside of our beverage where when we put the beverage in a styrofoam cup, it doesn't condense. So, condensation occurs when you have a cold surface in a warm moist environment. To keep the inside surface of the foam at or above the dewpoint temp, you need 2" of CC and 3-4" of OC. This should prevent condensation from occurring on the inside of the foam. So, what would happen when you apply an additional air permeable insulation material to the inside surface of the foam which is typically less than the 2". The question comes with the air permeable part as air carries moisture and can allow more moisture to travel to the inside of the foam and the foam acts as an air barrier (Yes, OC too!). So, when the moisture laden air comes in contact with the less than 2" of foam, CONDENSATION! If you think about it, it's really one of the last legs that the fiberglass has on the industry. It's their way of staying in the industry while muddling along with the foam. If they can't beat us then join us! Well, that's what they've done. In the mean time, all of the fiberglass companies are getting into foam. So, they're having it both ways. They get to have their cake and eat it too! So, I'm not a proponent of Flash-n-Batt insulation systems in any way and don't support it. Even if you have enough foam in the wall to prevent condensation, then it's not worth adding any more additional insulation -foam or not! So, regardless of what material is being used, OC or CC, you can still create a great indoor air quality and great comfort! Just my 2 cents!
Posted: Feb 01, 2010 06:57 PM	Jim, I have a lot of respect for your opinion, but I don't believe 3-4" of OC is enough to stop condensation. It just covers up the frosted sheathing and you can't see it. You need a proper vapor retarder. I also do not promote the flash and batt. I just happen to sub contract for fiberglass contractors. They are installing craft facing fiberglass over our 1.2# OC. If there is enough vapor in the air and it gets past the kraft facing, it will condense on the flash coat or the sheathing. It doesn't matter what is behind the fiberglass, vapor will condense if the conditions are right. It will also condense behind 3-4" of OC. Both systems rely on a proper vapor retarder. Our company only sprays foam. We don't do anything elese, except foam. The only reason we flash coat, is to stay busy. Again, nothing but respect for your opion, Jim. Just my humble two cents.
Posted: Feb 01, 2010 07:30 PM	Two more cents: On every job we spray, I reccomend quality bathroom exhaust fans, good kitchen exhaust, both vented to the outside and an HRV system. If moisture is controlled in the first place, then the vapor retarder becomes less important.
Posted: Feb 02, 2010 04:59 AM	ed,,remember,,it needs the next available air space to lay out on as condensation..which is why a spray foam system (either product) is superior in that it is "glued" to the sheathing... like sirjim replies,,it will be at the face of the foam if adequate thermal resistence(depth of foam) isnt there..and if you push the environmental or mechanically produced conditions to extremes you can make it happen in modeling at most any depth eventully,,, mechanical ventilation is belt over suspenders,,,and will manage the vapor as good as it could be done.. but the customer wanted cheap which is why he went with the BE system...persuit of steak on a hamburger budget...yum 'dude
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: Feb 02, 2010 11:49 AM	Ed, The open cell we spray has a lower perm rating which frankly, is over rated. The perm rating is a measure of the moisture vapor tranmission through the foam but in essence, an air barrier is the majority of the moisture vapor retarder. So, since you have an air barrier with only 1"-2" of open cell foam, the moisture vapor may condense on the foam and allow some moisture vapor to transmit through the foam. This is the key! Is it gets wet, you need to allow it to dry which is what the open cell does, The closed cell will not or will take longer to dry due to the lack of surface area and the perm rating of the foam. It takes longer to get in, but once the moisture is in the foam, it also takes longer to get out. Now the thickness issue - if the insulation is not thick enough to provide a high enough R-value, then there could be a condensation issue on the inside surface of the foam. If it is enough R-value (R-12+), then it shouldn't be a problem. So, if you follow these principles then you should be safe - regardless of what the code says we should do. I also agree that the ventilation system is typically a belt and suspenders type of approach and if you control the moisture to begin with, then that should do it. So moisture vapor should not be an issue if it's controlled and/or managed. That's what the open cell foam does, it manages the moisture level within the system.
Michael Fusco Posted: Feb 03, 2010 10:03 AM	Here's an arguement no one has made....CC foam is NOT a VB after one year. Having said that...VB's are an option for most of the lower 48...why do you think that is? In reality, when a failure occurs in a F&B application THE FOAM WILL BE AT FAULT, after all, fibre galss has been around for what...60 years...it must be good...but that new foam stuff..... By the way....had a very long conversation with the new product manager for one of the big advocates of F&B at IBS.....guess what....they are seeing failures of foam in F&B applications. Guess why....cracking. Hey Mason...to thin? Some day we will wise up and stop shooting ourselves in the head....got that line from my favorite manufacturer!
Roger Morrison Posted: Feb 20, 2010 07:53 AM	Flash and batt is a GREAT system for warm climates. It provides vapor retardance on the warm side (exterior). Omit the kraft facer on the the fiberglass and everything breathes in the right direction. In cold climates, things get dicier. Now, the combination of SPF and the exterior sheathing is acting as a vapor retarder on the "wrong" (i.e., cold) side. This must be compensated for with a very effective vapor retarder on the interior side. Also, air leakage from the interior into the wall assembly needs to be considered; electrical boxes and other wall penetrations should be air sealed. All of the concerns that have been previously expressed in this forum relate to cold climate use of flash and batt. But if you're operating in Climate Zone 3 or lower, go to it!