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Posted: Jan 02, 2007 09:09 PM	Closed Cell vs Open Cell I'm pretty new to this spray foam but I can't seam to find any reason to spray open cell foam in the res. market. Am I missing something? R-value per inch, structural advantage, air seal, less clean-up, Any thoughts would be great.
Dave Strnad Posted: Jan 03, 2007 06:25 AM	Well you are right, however the issue is cost. I just started spraying the other blends to compete locally. I'm not sure about costs in other areas, but here to use closed cell it typically is double the cost of cellulose. I can spray equivilant open cell for 30% less than closed. This allows me to get the foot in the door so to speak with people that have not considered spf. I try to sell the closed, but I will take the open if I can get it. I have two types of customers, the one that knows exactly what they want and the ones that haven't thought about it but like the idea of SPF. For me the customer that calls me and wants a bid for X of inches, is usually after closed cell. The customers that I approach will usually go with the open cell. It could be that I'm not a very good salesman.lol. Some people want the best and others want something close that costs less.
Posted: Jan 03, 2007 09:25 AM	Someone please correct. Half pound foam is not water resistant and appears to absorb water. If this is true why would anyone ever put half pound foam into a building structure? Leon
Gerry Wagoner Posted: Jan 03, 2007 06:20 PM	Closed cell is superior to open cell in several aspects. regarding foam insulation, we need to help people understand the difference between price & cost. One singular advantage of open cell is filling in the underside of deck flutes. The aggressive expansion allows greater coverage with less material. A notable disadvantage is the ability of open-cell to absorb water. I predict that our industry may experience some issues in this area eventually. olger
Dave Strnad Posted: Jan 03, 2007 10:08 PM	I agree with the price vs cost approach I use a work sheet to show people the savings. I try to sell the closed but I'll take the open jobs if I can get them. Regardless of the flaws I still think open is a better product then fiberglass or cellulose which is the alternative. The thing that I have a hard time with is that the big cost savings is primarily from the air seal, which any of the foams will do a good job of. SO the only real difference is the strength, higher r-value per inch, and water vapor retardant. While these are all good features they are harder to sell then the energy savings. People always ask if they will save any more money if they go with the closed cell vs open cell. I never know what to say. I always tell people that I would put the closed cell in my house and then talk about the benifits and why.
Posted: Jan 04, 2007 09:09 AM	Personally and just from what little I know, I would never choose to put .5lb foam into a building if it absorbs moisture and holds it. I'm having a hard time figuring out why so much .5lb foam is being put into buildings if there's going to be moisture problems down the road. How are the big .5lb foam companies and installers justifying the fact that .5lb foam retains moisture? Is there anywhere in the country where they were putting .5lb foam in walls 20 years ago? If so, these houses are probably being or have been renovated recently and this should be a good guage of what .5lb is and isn't doing. Regards, Leon
Lane Hogstad Posted: Jan 04, 2007 04:55 PM	I'd like to hear about some first hand stories of problems with open cell. If used and installed properly it should never be a problem. If open cell gets wet so will sheetrock, fiberglass, studs, anything in the way. If you have those problems its not from the insulation its from another source. I don't see improper venting, or a water leak, as an issue that I would be held liable for. I've heard alot of theory never an instance that open cell caused a problem if used above grade with common sence. Thanks and lets hear stories. LLH
Dave Strnad Posted: Jan 04, 2007 05:26 PM	Am I missing something about the open cell? I realize that it can take in water, but so can cellulose or fiberglass. How would open cell foam cause anymore of a problem then cellulose or fiberglass?
Robert Taber Posted: Jan 04, 2007 05:43 PM	Yes, the debate continues. There is no way to realistically say that one type is better than the other in all applications. Of the numerous architects and building science professionals I have spoken with, it usually comes down to the statement "it depends". No doubt, either product is better than fiber and will both work effectively at reducing energy consumption. The moisture question is one that keeps coming up in debate. Yes, open cell foam will allow water to enter into it (hence the name "open cell"). However, of all the applications I have done that managed to get wet during the building process, all were dry in a matter of days. If water is getting into the insulation after construction, you have much bigger problems than wet foam. In hot / humid climates water vapor transmission plays a big part in deciding which type of foam to use. Closed cell vs. open cell. Use either one, install it properly and at the right depths, understand the charateristics of each and sell with knowledge.
Posted: Jan 04, 2007 08:33 PM	So as we get back to the cost issue. Is there a real cost difference per "R" for the two products? It appears to me that the time saved during clean-up and not trimming the closed cell should offset the added material cost.
Posted: Jan 04, 2007 09:14 PM	With closed cell you must still trim the overspray off the studs and rafters and any other place it make have landed. So there is still cleanup and trimming regardless of the type of foam. Tim
Robert Taber Posted: Jan 05, 2007 07:47 AM	I have found that our margins are a little bit better with open cell than with closed cell. But, and indeed it is a big but, good spray technique is the primary reason for good margins. Myself and my other sprayers are usually able to limit the amount of open cell trimming by just filling the cavity and limiting waste. Gun must be clean and working properly, no sticking or trigger delay. Of course machine temps and pressure should be watched and adjusted to insure good yield. I'm not saying anything new, all this stuff is basic. We spray about 60% oc vs cc. With the fusion air purge we have to ream the mix chamber more often when spraying cc to get a good pattern and avoid hitting the stud face so much. Of course every once in a while we remove way too many bags of oc trimmings and that puts the labor for that job too high.
SprayFoamSupply.com Posted: Jan 06, 2007 07:25 AM	When I price jobs, I give the customer options. I price both open and closed cell, explain the differences to the customer and let them and their budget decide. The job that we are on right now is getting closed cell in the walls and open in the attic sprayed down onto the drywall with a vented attic. The house has a 12 pitch roof and spraying the underside of the roof added substantially to the cost. Open cell foam does not ABSORB water! It ALLOWS the passage of water and water vapor through it. There is a huge difference! If you understand this and design accordingly, there are no issues. For example, I am in NH and require a vapor retarder (VR) on the inside when using open cell foam. This VR is really only needed in the coldest part of the year when it is below freezing outside and the air has very low humidity. Mother nature wants to have balance, she doesnt' want to have 70 degrees inside the house and 0 outside, she wants 35 everywhere. Not exact, but you get the idea. The same goes for humidity, in winter she doesn't want 0% humidity outside and 30-40% humidity inside depending on the occupants and their habits. Just as heat moves to cold, higher humidity moves to lower humidity. This is called the vapor drive. When conditions are right, this humidity, or moisture in the air wants to force its way though the open cells of the foam toward the outside of the structure. If it reaches a surface where it can condense, it will, that is where problems can occur. It is not a problem, so long as the moisture can continue on it's path to the outside. Take my current job, no VR on the ceiling. Any moisture that forces it's way through the foam and condenses on the top of the foam will be allowed to evaporate into the attic. If we had sprayed open cell to the underside of the roof deck creating a non-vented attic moiture coming through the foam would condense on the underside of the roof, possibly mitigate through the sheathing, but would not go through the shingles and be allowed to evaporate. In theory, not a favorable installation. In reality, very minimal moisture is going to get forced through 8-10" of open cell foam. The vapor drive only exists for us in NH for a short time, especially this year. What weather we've had! Get out there and get foaming. The more houses we foam, the more energy we save and the more we can help slow the global warming! That's a whole other post. RobertT is right, if you have water getting into the structure it is by no fault of the foam. Buildings should not be built where they rely on the insulation to keep the water out! If open cell gets wet, it will not retain that water, it will dry out much faster than fiberglass or cellulose if it is allowed to. Dave, when people ask me if they will save more with closed then open, I tell them that closed is a better product and will perform marginally better than open. I remember that oak ridge did some attic assembly testing and that the closed cell performed closer to it's stated r-value in the field than the open cell. If they have any moisture concerns, and they can afford it, they usually go with the closed. I am curious, don't your suppliers have the answers for you? George
Posted: Jan 06, 2007 10:31 AM	"I can't seam to find any reason to spray open cell foam in the res. market." open cell foam is a great insulation product when processed and applied properly... it affords an air barrier far superior to tradional insulation and air barrier products.. it seals and insulates in one application,,, air inflitration is what deminishes the rvalue of structures insulated with porus/open cell type of insulation materials...seal the cracks, seams, joints and penetrations to air movement and the structures wall performs closer to the design rvalue it was spec'd with.... use open cell foam when you have adequate depth to apply to design spec rvalues... be certain the structures "systems" have been designed with sound building science practices...and with to accomodate the exteme "tightness" a foam structure can afford... closed cell foams afford the maximal thermal performance available in the insulation market,,you get what you pay for... i use it for my building envelope type applications, as well as those cavities which are limited in rvalue obtainable due to depth constraints,,,yes i apply it as a stand alone insulation product too.. i apply to design spec rvalues,,,minimum,,no matter what product we apply.... we offer the customer the various options/recommendations available to them and try to educate them enough to make the decision as to which application is the most cost effective to them...as sometimes economic comprimise dictates the system chosen.... like olger said above...we will see issues in the future if we have shoddy applications being made in the world...we will have issues if good building science and average building common-sence is ignored...
Posted: Jan 06, 2007 10:57 AM	"Half pound foam is not water resistant and appears to absorb water. If this is true why would anyone ever put half pound foam into a building structure?" uhh,,,neither is wood,,,filterglass,,,cellulose,,,dry wall,,,1" foam (board stock or spray).... so,,,if you use the foam as a component of the total wall system,, and as an insulation product in this wall system,, that has been designed and built with good building science and practices,,,then the foam would afford the structure a wall system whose design rvalues can be maintained under "adverse operating conditions"....the type of conditions that cause other systems to loose their performance rvalues by significant amounts.... as mentioned above....foam is not meant to be an water barrier,,,some foams at appropriate depths can be vapor barriers,,,(oh poop i said the VB word,,,:)...) foam will not absorb moisture,,,but it will hold moisture if it is subjected to it with no drainage plane available to it...even closed cells are about 97% closed cell or so...so they too will "hold moisture" if subjected to hydrostatic pressure... so dont be afraid to put foam into the walls for insulation...it is a great product that will afford you an air barrier that the other products cant,,,less dust,,less allergens,,,less noise... superior thermal performance,,,less operating cost to heat/cool the structure...come on man give it a look,,,foam good...
Posted: Jan 06, 2007 11:13 AM	"I'd like to hear about some first hand stories of problems with open cell. If used and installed properly it should never be a problem." if we install to r19 (of any foam) in in attic that requires r-38 to r-48 by geographic location we could have problems...not enough insulation to stop the ever present transfer of hot to cold...and when hot meets cold,,,condensation occurs...no longer moisture vapor it is unable to be "ventilated" by the structures roof vents,,and sits on or soaks into the insulation material...hopefully to dry,,,by evaporation...over time this moisture could accumulate if it doesnt evaporate or drain,,,the potential ramifications are endless....(the sky is falling) r value is rvalue..physics is physics...
Dave Strnad Posted: Jan 06, 2007 08:24 PM	foamdude, are you saying that you always apply to regional r-values? If so what region are you in? Where I live that would be 10-13" of open and 5.5-7" of closed. I have been having questions about this because it seem the practice is 8" of open or 4" of closed in the attic. So far I have sprayed between 4-6" of closed on the jobs I've done, but have always been a bit nervous about doing so. I can say that every job I've done the customer has been very satisfied, but this delema is still in the back of my mind. I always give the customer the option for extra but only a few go for it.
Posted: Jan 07, 2007 09:15 AM	dave...always? no not always, but when ever the economics of doing so allows,,, with r-30 in a lid/attic you do not have an ENERGY STAR application.. with r-30 in a lid or r-15 (4" OC)in a 2x6 your customer is not eleigable for most energy efficient rebate programs...nor the 2005 energy tax credit... i use this analogy frequently when spraying/bidding foam work... working in the building trades is like walking along the edge of a cliff.... we frequently have choices/decisions that allow us to walk a step back from the edge,,,although sometimes we can make decisions that have us teetering out on the edge...we try to make the decisions that keep us as far from the edge as possible..
Posted: Jan 07, 2007 09:21 AM	Has anybody had a code officail sign off on less then the required R value knowingly? In SC the Ceiling require an R value of 38. That would be 5 1/2" of closed cell. I can't see selling that cost. Has anyone had the engineering done on whole house performance? taking into acount the heat loss, window, air infiltration etc.
Gerry Wagoner Posted: Jan 07, 2007 10:28 AM	Throughout the world, the design spec for a blast freezer is 3.5" of closed cell foam. The average temperature for these units is -22 F°. In a residence, 4" of rigid foam is easily adequate for all but the most severe climates. As to the water absorption properties of foams, we have conducted testing in our shop by submersion and weight gain formulas. Most notably however, is a run of open-cell foam that I sprayed in the lower wall section of our new shop addition (it's what we had in the lines of one of our machines at the time). This foam has/had access to the outside elements through cracks in the metal skin/siding. On two occasions, the open-cell foam allowed water to wick into the shop interior using the soft foam as a vehicle. Those of you attending Spray Foam in Orlando, please beat me over the head for using any open-cell near an inclement water source. (Icynene is under various lawsuits for this very characteristic.) Sure, cellulose would have done the same thing. As an industry we need to make the difference between the two foam types a bit more distinct. as you were, olger
Jeffery Dieu Posted: Jan 07, 2007 12:13 PM	A little off key here, but I for some reason I get this gut feeling that this Closed vs Open was started to try and make the overall foam industry look bad. I have to ask jodyfitz, are you really in the foam industry or are you a cellu guy who is angry at foam cutting into your business?
Posted: Jan 07, 2007 12:49 PM	Good question. I am looking into starting a spray foam business. One of the material manufactures that I am talking to only offers the Closed cell product. I am originally from Vermont so the whole energy savings ideas are engrained in me. As I continue to educate myself I am asking the questions that I know will come up later. Any input is great. I am really happy with the amount of descusion that I have raised with this forum. You guy just keep feeding me information. Thank you.
Posted: Jan 07, 2007 11:48 PM	I agree, this is a great thread. I'm looking at the business too and this thread addresses at least a few things that have caught my attention. If it catches my attention than it will probably catch the customers attention and need to be addressed. I was just visiting the insulation forum at the HGTV website. There are a lot of hits on threads about sprayfoam insulation there. It doesn't seem like there are many informed sprayfoamers there setting people straight. I read in a few threads about people not wanting to install closed cell because it out gases too much!? And nobody has addressed that concern. I'm looking forward to seeing some englightning disagreements in Orlando. Leon
Richard Russell Posted: Jan 08, 2007 11:33 AM	George: is there any particular reason for not use a vapor retarder under the ceiling where you are using the open cell above? Granted, the permeability of that thickness of foam will be only a few perms, so that the concentration of water vapor diffusing through the foam likely never will reach the dew point concentration at any temperature across the foam. In general, my thoughts for spray foam contractors are: 1. Educate yourself thoroughly on "building science" issues (already suggested above). Start with buildingscience.com. Selling a more expensive insulation than FG (shudder) or cellulose means you will have to speak convincingly about the technical aspects, with respect to movement of heat and water vapor. 2. Your selling point against FG is that the home will never get R20 out of a FG-insulated wall built to R20 code when R20 is needed most - very cold weather. Against dense packed cellulose, open cell foam is harder to sell, since the R/inch is so close. Selling points are superior sealing (but sealant between framing members is very important also) and a self-supporting structure that can't settle over time (supposedly dense packed cellulose is packed tighter than the natural settling density and can't settle so as to create voids, but any upset condition that intruduces wetness changes that). 3. If space permits the required R of the wall to be met with open cell, then it is less expensive. Don't ignore thermal bridging; a 2x6 framed wall at 16" OC with closed cell foam will give about R36 through the foam at 6.5/inch, but averaging in the heat loss through the wood studs reduces the whole wall R to around R24, or less if losses through top and bottom plates are considered. That's still better than perhaps R10-12 effectively for FG when it's zero outside. Still, that thermal bridging is costing a third of that expensive closed cell foam. Bottom line: learn to calculate total wall average R value, and don't be afraid to show the calcs to the homeowner. If you get an engineer for homeowner, he can do his own calcs, and his numbers had better agree with yours or you've lost credibility. If he isn't technically savvy, at least you've done something to establish your credibility. 4. If the whole house is going to be very tight with the addition of foam, make sure to address mechanical ventilation (HRV). The old excuse about making the house "tight, but not too tight - the house has to breathe" is pitifull, considering what is known about building science today. If you make the house very tight without mechanical ventilation and air quality suffers (humid, stale air), that will be seen by the non-technical homeowner as a reason to "never use foam again" and you'll be unlikely to get a good reference from him. 5. No insulation, open or closed cell foam, FG, or cellulose, will protect the structure from moisture if the exterior is not protected from rain getting behind the siding. It is now understood that wind-driven does get behind any kind of siding, and the wall does need to dry out between such events. Windows need proper installation and flashing, and the housewrap needs to be in place and shingle-lapped correctly. If the exterior leaks, eventually the wood will rot or become moldy, and it will have been better to leave the house leaky and energy-inefficient. As the foam contractor, you don't want to be a part of that end result, so you perhaps need to take a bigger role in all aspects of the house envelope than just the foam. Get educated so you can be associated with good results, not bad ones. Well, enough soap-boxing for now. Hope I don't get flamed too badly over any of this. If it serves as further discussion, that's good.
SprayFoamSupply.com Posted: Jan 09, 2007 08:51 PM	Hi Dick, The foam performs better when adheared to the back of the drywall and not lifting off of a plastic vapor retarder. The customer didn't want to use the vr if he didn't need to. George
Richard Russell Posted: Jan 10, 2007 07:27 AM	Is the HO using a low-perm paint on the ceiling, then? I have a more general question. At some point, someone perhaps did calcs on diffusion of water vapor through various materials and, considering some low design temperature for a given interior moisture concentration, figured out what perm value was needed for a vapor retarder and then picked 1.0 to be safely below what might just result in condensation under adverse conditions. Either that or the value 1.0 was found to be a safe number to spec based on field experience. The more general question then is, for typical cold climates (New England), what perm value is closer to borderline? If 1.0 is the spec, would 2, 3, 5 still likely be close enough? Perhaps this is a question to bounce off Building Science Corporation.
Dave Strnad Posted: Jan 10, 2007 07:59 PM	I thought that ceilings did not need a vapor barrier if they where vented. Wouldn't the vapor just diffuse through open cell into the attic. In fact one of my local inspector has concerns that the water vapor can not difuse through closed cell and into and out of the vented attic this was one of his reasonings for a HRV. A vapor barrier shouldn't be necessary unless applied directly to the underside of the sheeting.
Posted: Jan 11, 2007 07:15 AM	if you seal a home with foam..hybrid system or not(sides only,traditionally insulated attic),,,you should incorporate an hrv/erv into the hvac system...we do make these structures very tight... i see hrv/erv in cellulose and fiberglass homes as well as every foam home we do... "build it tight...ventilate it right...manage the indoor air quality for a healthy structure"... dick,,if i get time i will run a wall system on wufi and on HAM and get the results up here... last i looked,,, as i remember..,,(poop for brains here)...open cell system in 2x6 sidewall, 75 degrees in,,30%rh with -10 out,,,50%rh (programs do not allow for wind drive) and the wall with out VB was subject to ~200 grains of h20/sq ft/day while the VB wall was subjected to 10 grains/sq ft/day...
Posted: Jan 11, 2007 12:48 PM	What is a good software for comparing Fiberglass vs Foam insulation? Is anything setup of the heat load calcs?
FirstName LastName Posted: Jan 11, 2007 08:34 PM	i use oc and cc. the only thing i would ever use for myself is cc. if the owner wants oc because of price he/she wants better not best shame on them. like apples and oranges. no one has ever given oc more merit than cc that ive ever heard?
Posted: Jan 11, 2007 09:17 PM	What is the cost difference in-place per board ft?
FirstName LastName Posted: Jan 11, 2007 09:35 PM	oc verses cc. if your an oc guy you hate cc cell, vise-versa. r-value for r-value (mythical of course, not to mention) oc is slightly cheaper. real time performance- no comparision. i use both but hate to use .5 lb. 1.2 and 1.5 not to bad, but really love 1.7 and above. nothing is better 2.5 any where.
Posted: Jan 11, 2007 11:50 PM	foam4me, When you say that cc is slightly dearer than oc what is slightly. If you were quoting to do 2 inches of cc or 4 inhes of oc what would job quote pricing be. Thanks.
Posted: Jan 12, 2007 06:34 AM	r value is r value... it is a unit of standardization of measure...of which all materials possess,,,even air... it is the recipicol of K or U value... the total depth of material devided by the U value equals the r value of the said depth... it is not a myth,,it is physics... how it is "used/represented" is often some of them there funny numbers,,and no,, wind is not taken into account, nor is crappy installations... but is a way to prescribe a design r value to ensure that said spec is being met. we run about 30% less for OC to CC for uncomplicated sidewall applications,,,but as the vendors continue to raise the cost of materials this is getting closer...and as mentioned above,, it is getting close enough that with proper education and information the informed end user will upgrade to CC...you get what you pay for..
FirstName LastName Posted: Jan 12, 2007 08:18 PM	first r-value real or mythical? real by mathmatical, false by efficiency(my opinion). I know that 4" of cc foam in a vaulted ceiling is better than a r-38 or 40 of fiberglass insul. proven by energy savings. i also know by my home that a skim coat of cc in a stud cavity with r-11 fiberglass insul is more effficient than an r-19 of fiberglass alone, r-value for r-value the combo will highly outperform fiber only. end result is r-value just math, a home owner isn't buying math, a home owner is buying lower utilities, which with foam insul means the home owner will save more by using less r-value in foam than more r-value in conventional insul. it is proven! that is why i say r-value is mythical. and cc is better than oc because of moisture control, when any insul gets moisture in it the insul suffers. so if a home owner wants to save on a superior insul give them the option of the best, and explain why it is the best. cc is better.
FirstName LastName Posted: Jan 12, 2007 09:04 PM	if r-value is r-value due to physics than why would anyone want to save more by capitalizing on spf. and if oc is better than cc why not use oc on roofing or freezers of other areas of difficulties like marine applications. that alone will tell the differences. the harder the job the harder the foam.
Timothy Sonney Posted: Jan 13, 2007 12:45 AM	What the customer has to understand is what they are getting for their money, and what your local code requirement is for their area of the country. In some areas of the US Open Cell will meet the code requirements, and in other areas of the US Closed Cell is the only option DEPENDING ON WALL DEPTH. Open Cell has an average R Value of about 3.5 - give or take a couple of points. Closed Cell is almost 7. Most construction in our area has 2x4 exterior walls with a code requirement of R-19. Simply math will explain that Open Cell will not meet the requirements requested by law. Closed Cell will. This isn't a question that has an answer that will work for all of the USA. You have to look at what is required by code. I invite you to visit our Site to see what our requirements are here in the NorthEastern part of the US. I have Closed Cell in my home except for 1/4 of my attic that I used as a test. I installed 3" of Closed Cell Foam on a section of my roof, and used 5.5" of R-21 Fiberglass Insulation on the other. Our first snow fall I went out side and took a picture of my roof, and you will see the area that has the Fiberglass is showing all my Shingles, HOWEVER the area that has 3" of Closed Cell Foam is COVERED WITH SNOW!!!!! They say a photo is worth a thousand words.....take a look.... follow the link to the left and see. Proof is in the SNOW. George - You are right "Open cell foam does not ABSORB water! It ALLOWS the passage of water and water vapor through it" - This is when it comes down to the insulation contractor to direct and educate the the customer about what is the best product to use in each application. We all should have a good knowledge about our weather conditions in our area's.... we live in them... Insulate your customers homes as if they were your own homes. jodyfitz - "That would be 5 1/2" of closed cell" We have done homes in the past that the customer wanted it thicker, so the customers are out there, in our area that is. Olger - "the design spec for a blast freezer is 3.5" of closed cell foam." The requirements for this is mainly due in part to the amount of humidity acording to the size of the freezer. Much research and math needs to be done for onsite built freezers/coolers VS. prebuilt units. If you need info on these let me know, I'd be happy to talk to ya. This is just our output on the entire OC/CC battle. Any questions please respond.l
SprayFoamSupply.com Posted: Jan 13, 2007 07:07 AM	R-value is real, but it only measures heat loss or gain due to conduction. It is a lab test and doesn't apply to heat loss from convection or radiat heat loss. The greatest savings from foam is because it eliminates the convection heat loss. CC is better than oc in most applications, but oc will provide great themal performance and if that is all the budget will allow for, so be it! If the house is designed and built properly, the insulation shouldn't be getting wet. I don't think that anyone is trying to say that oc is better than cc, but oc is better than fiber or cellulose. Everyone here should know why you can't use oc, on roofs, freezers and marine! If not, you shouldn't be spraying foam. foam4me, how long have you been spraying? George
FirstName LastName Posted: Jan 13, 2007 09:05 AM	5 years. i started as a closed cell guy. now i spray open if that is what the customer wants. i inform them of the differences and usually they change to cc. been doing alot of roofing those flat/low slope roofs.
Gerry Wagoner Posted: Jan 18, 2007 09:52 AM	Olger - "the design spec for a blast freezer is 3.5" of closed cell foam." The requirements for this is mainly due in part to the amount of humidity acording to the size of the freezer. Much research and math needs to be done for onsite built freezers/coolers VS. prebuilt units. If you need info on these let me know, I'd be happy to talk to ya." Thanks for the offer BH. I also appreciate your shingle pictures from your own house. We have done something similar with our own home. As to coolers, I sprayed my first cooler in 1985, for Victory warehouses in Dayton. 3500 ft². Still working well. I am also acquainted with the principles of water vapor transmission as it is measured by hydrostatic formula / WUFI. I have also learned a lot from Roger Morrosion over the last 20+ years, as we jointly designed several systems for large customers. I am still amazed at foam's abilities. 3.5" of rigid is still the normative design spec for blast freezers. The variable is the type and placement of the vapor barrier. If we rely on the insulation to generate the vapor barrier, the system is destined to fail (this is for the less experienced ones on here) in cold storage environments. Illustration: You can have up to .5 psi hydrostatic drive on an exterior nitrogen tank. Hope to see some of you in Orlando, olger