Hello. I am looking for comments by those who have experience with P2000 outsulation. It is applied outside of the sheathing of the structure and has an inner membrane and outer membrane that are moisture resistant/proof and thermal reflecting. The material is either 5/8 or 1 inch thick and is applied in 4×8 sheets or in a continuous band. There are tabs of the membrance on allsides so that the membrane becomes continuous without defects after application (that is the theory).
I am looking for comments based on experience with this material. We are building a new home in central Ontario. The frameing will be standard stick framing with sheathing applied and then the P2000 applied on the outside. The outer envelope is galvalume with standing seams. Water handling will be at the base of the walls with french drains eliminating eaves, soffits, etc.
The material does not have an R rating. I am told that a 1 inch application is equivalent to R28 but the performance is diffferent because it emphasises an impervious vapour barrier and thermal radiation barrier.
The idea is very attractive to us as the mmodern design lends itself to elimination of drywall etc. I’m interested in any comments
Thank you
Replies
I'm pretty sure that R28 per inch claim is complete BS. You might want to see what the Canadian consumer protection folks have to say about this product.
run, Forrest, run.
For reflective insulation to be effective, there has to be an airspace. Period.
P2000 has not been tested to any standard. The tests are agreed upon in house tests done by intertek. Go to the reflective insulation manufactures association site to see how it is supposed to be installed.
http://www.rima.net/
Edited 1/1/2008 7:21 pm ET by rich1
Thanks for the responses. This product is manufactured in New Brunswick. I know of only a few applications in Ontario to this point.I have so far been told the following about outsulation - please help me if I need more information1. Outsulation avoids the "R voids" that arise from studs interrupting the insulation
2. An impervious membrane is important and outsulation of this nature provides this. There are perimeter self-adhesive tabs on the material which provide a continuous seal. Given how I have seen other building envelopes applied (Tyvek etc) I cannot imagine that they actually provide a seal. Can they be applied in a way that they actually work in the short term and long term.The design calls for exposed framing - which we like (and it coincidentally avoids the expense of drywall and finishing drywall etc. If we want to use outsulation what products are out there that you may have experience with?thanks again for your time. I appreciate people's responses to pretty novice questions.Mark MacLeod
Sorry for the late response.
No such thing as outsulation.
p2000 has an r value of 4 per inch if there is no airspace. If there is a minimum airspace of 3/4", the r value increases.
But explain to me, what is an "apparent" r-value. Either you have a value or you don't.
If you wrap a house with it, the heat loss will decrease. But a good part of that is due to a reduction in infiltration. Real expensive vapour barrier.
Rich,
"Outsulation" is a newly coined word referring to insulation installed on the exterior of a home's framing. The use of this slang word is jocular.
P2000 insulation claims have been investigated and challenged by several governmental authorities, including the Safety and Buildings Division of the Wisconsin Department of Commerce and Canadian authorities in several provinces. According to Energy Design Update (August 2006), the testing laboratory that is cited by the manufacturer of P2000 as a reference for its exaggerated R-value claims has released a public letter calling the P2000 claims "misleading."
P2000 comes in several thicknesses. The 5/8-inch product has an R-value of about 2.5, while the 1-inch product has an R-value of about 4.
I think what I am asking is that even though the R value is low, does the material work in any different way as far as heat transfer is concerned.If we want to insulate on the outside of the framing, what is the best way to do it. How does the vapour barrier work? Would SIPs outside of the framing be a good idea. I"m really struggling with the concept so I need all of the help I can get.I will say from many observations that the way that house wrap is put on leaves me with zero confidence in it's function. I don't think I have seen a house under construction where there wasn't something really obvious wrong with the wrap - without looking very hard.Are there other posts or threads that have the info I'm looking for without repeating it all here?
The way they recommend installation, it does act differently.
When the reflective surface comes in contact with another surface, it now becomes a conductor, not what you want in an insulation.
Build to r2000 standard. Use spray foam if you have someone nearby. Use an hrv, and direct vent appliances to heat. No need to overthink this.
If we want to insulate on the outside of the framing, what is the best way to do it. How does the vapour barrier work? Would SIPs outside of the framing be a good idea. I"m really struggling with the concept so I need all of the help I can get.
Well, you could search the site here for Poster = Raymoore and "PERSIST"
The PERSIST system is a method of insulating outside of the framing. It's been updated to move the vapor barrier plane to the outside as well.
I want to remember the primary feature was 2" of isoboard, but danged if I can remember the sheathing & VB details just this second.
All of this was based in good building science, too, not the sales brochure for a insulation company (which could be suspect, to a jaundiced eye).Occupational hazard of my occupation not being around (sorry Bubba)
Installation of housewrap is pretty straight forward.
You mention that you have yet to see a house being built where there wasn't something obviously wrong with the housewrap.
Curious how this new product that many haven't even heard of, would somehow be installed proper. Seems to me there would be much more chance of a mistake on the install of P2000 than simple housewrap.
yes, I know and hence my concern . . . . a product I don't know that has a high technical requirement .. . . . . I don't want to take the galvalume off!
You should get a contractor involved in this project ASAP. Sounds like your architect wants to be cutting edge but doesn't have the technical ability. This isn't uncommon, in fact its expected.
It also sounds like he understands your aesthetic needs and that is important. Let him draw it and let your builder make it technically correct.
Here is a letter to the editor and the reply. It is from Energy Design Update, June 2006.
Dear Editor,<!----><!----><!---->
There is an insulation product called P2000 that is making inroads to the northeast US, distributed through 84 Lumber. Their Web site is at http://www.p2insulation.com.<!----><!---->
They are claiming their 1-inch beadboard styrofoam (EPS) with foil on both sides is R-20 per inch of thickness. My question is this: Given the fraudulent Rvalue of this material, how does one go about getting the FTC to ban it? I thought there was a federal rule that brought gloom and doom to liars like this. How do I go about getting the ball rolling?<!----><!---->
Pat Dundon<!----><!---->
Dundon Insulation<!----><!---->
Windsor, New York<!----><!---->
Editor's Reply<!----><!---->
Pat Dundon is correct: the exaggerated claims made by the manufacturer of P2000 insulation are blatant violations of the federal R-value Rule. Anyone wishing to report inflated R-value claims should contact Hampton Newsome, Federal Trade Commission, 600 Pennsylvania Avenue NW, Washington, DC 20580; Tel: (202) 326-2889; E-mail: [email protected].<!----><!---->
P2000 is a brand of foil-faced expanded polystyrene insulation manufactured by Polar Industries of Prospect, Connecticut, under a contract with a Canadian building products manufacturer, R. R. & D. Enterprises (633 Chemin Sainte-Claire, Rivière Beaudette, Quebec J0P 1R0, Canada; Tel: 450-269- 3197; Web site: http://www.p2000insulation.ca). It is distributed in the US by a Missouri company called Perka Building Frames (1111 Alabama Street, St. Joseph, MO 64504; Tel: 800-467-3752; Web site: http://www.p2insulation.com).<!----><!---->
The manufacturers and distributors of P2000 make several outrageous claims. According to one marketing document, "P2000 insulation system with 5/8" board, average R-value = 18.95." Another document trumpets, "A calculation of the R-factor has been made to different temperature gradients within the required range. Values show that the P2000 ¾" Bronze Insulation System is comparable to the 6" fiberglass insulation and that the P2000 1" Bronze Insulation is comparable to the 12" fiberglass insulation." Still another document claims, "P2000's insulation performance has been tested by a recognized testing lab under extreme winter temperatures. In that performance test, P2000 (one inch) performed equivalent to R27-significantly better than 6" of fiberglass batting." Elsewhere, the company claims, "P2000 is a new super-efficient thermal insulation product that delivers R20+ insulation protection in a one-inch board. It's tested! It's approved! And it works!"<!----><!---->
Readers of EDU will not be surprised to learn, "It's a lie!" For the record, 5/8-inch expanded polystyrene has an R-value of about 2.5, while 1-inch expanded polystyrene has an R-value of about 4. The product's foil facing has no effect on its R-value. (If foilfaced foam is a component of a building assembly that includes an airspace adjacent to the foil facing, the entire building assembly, including the airspace, may have an R-value higher than the insulation alone.) To justify its exaggerated claims, the manufacturer distributes copies of reports produced by two testing companies, Intertek Testing Services of Lachine, Quebec, and the Center for Applied Engineering of St. Petersburg, Florida. (The Center for Applied Engineering, a former subsidiary of Celotex Corporation, ceased operation years ago.)<!----><!---->
Intertek tested several building assemblies according to its own idiosyncratic test protocol; there is no evidence that Intertek used accepted ASTM methods for determining R-value. The Intertek test report lacks a clear description of the materials used to fabricate the test assemblies. The report includes this disclaimer: "Note that the R-factor is not absolute due to non-homogeneities in the system under study. For example, the test samples (boxes) were designed to represent real-life buildings and therefore are not perfect scientific models; they consist of several materials, they are not leakproof and let the cold air inside; most importantly it introduced several thermal breaks throughout the surfaces. Values must be looked upon in comparison rather than in absolute values. ... It shall be noted that, though the description 'R' factor is utilized when discussing the results, the nature of testing performed does not pretend to provide results which should be compared to those obtained from testing against standardized test methods like ASTM C-518."<!----><!---->
According to Intertek employee Eric Gilbert, "It was an R&D test for research and development purposes. That's all we can say. Intertek has a policy of not giving out information on the procedures and testing that was agreed upon between Intertek and the client."<!----><!---->
P2000 also distributes a November 1995 test report from the Center for Applied Engineering, written in part by Stanley Gatland II. (Gatland now works as the manager of building science technology at CertainTeed.) The test report includes the results of two ASTM C236-89 tests. This test, titled "Standard Test Method for Steady-State Thermal Performance of Building Assemblies by Means of a Guarded Hot Box," is intended to test the performance of building assemblies, not insulation.<!----><!---->
One of Gatland's ASTM C236-89 tests measured downward vertical heat flow through a roof assembly consisting of several layers of building components. From the bottom up, the assembly included a layer of ½-inch drywall, a ¾-inch sealed airspace created by 1x3 strapping, a layer of 5/8-inch thick P2000 insulation, a 1 ½-inch sealed airspace created by 2x8 purlins, and steel roofing with air-sealing materials inserted into the tops and bottoms of the air channels formed by the roofing panel ribs. When tested with the exterior at 100°F and the interior at 70.4°F, the building assembly had a thermal resistance of R-12.3.<!----><!---->
Gatland also performed another ASTM C236-89 test at different temperatures. The second test measured upward vertical heat flow through the same roof assembly, with the exterior at -2°F and the interior at 83.6°F. Under these test conditions, the building assembly was found to have a thermal resistance of R-7.5.<!----><!---->
Neither of Gatland's test protocols measured the R-value of P2000 insulation. In a 33-page document distributed by P2000, "Application Installation Manual," the P2000 marketers excerpted tables summarizing the results of Gatland's two tests, appending photocopies of Gatland's signature beneath the tables. Astonishingly, the marketing document declares that the ¾-inch thick P2000 insulation has a total R-value of 19.8, derived from the sum of the thermal resistance values measured in Gatland's two separate tests of building assemblies. According to this marketing document, Gatland's results showed R-12.3 under summer conditions and R-7.5 under winter conditions; ergo, the total R-value is 19.8.<!----><!---->
Reached by telephone, Gatland expressed frustration with P2000's marketing campaign. "You can't take the two test results and add them to make a total. They don't understand the physics behind the testing."<!----><!---->
In a follow-up e-mail to EDU, Gatland wrote, "Results are specific for the assembly tested and cannot be added to give a total thermal performance. In addition, reports are not allowed to be used in publicity or advertising. Every report issued by the Center for Applied Engineering, Inc. had a disclaimer at the bottom: 'This report is for the information of the client. It may be used in its entirety for the purpose of securing product acceptance from duly constituted approval authorities; however this report or the name of Celotex Corporation shall not be used in publicity or advertising.'"<!----><!---->
One US distributor of P2000 insulation, Gary Demasi of Honesdale, Pennsylvania, admitted in a phone conversation with EDU that the company is currently under scrutiny. "We've had disputes with other companies," said Demasi. "They all want to get their hands on the lab reports. We've recently had some great difficulties with these people."<!----><!---->
<!----> <!---->
<!----> <!---->
From Energy Design Update, June 2006
Here's a P2000:
http://www.hecklerkoch-usa.com/products.html
Kowboy
...my second most favorite topic. Here's the State of Wisconsin evaluation report to support Martin's comments above.http://commerce.wi.gov/SBdocs/SB-commercialBuildingsXProductEvaluations200602-I.pdfBe sure to read the "LIMITATIONS OF APPROVAL".
______________________________
rb
Edited 1/8/2008 12:36 am ET by RBean
You're preaching to the choir. LOL
Haven't seen the intertek letter yet, I'll have fun with that one. I know the local rep.
EDIT; Just checked the newsletter, the letter is from the polar industries which makes the eps for p2000. Intertek did the testing. p2000 supplied the test hotboxes. The p2000 box had p2000 on all 6 sides. The fibreglass box had wood, no insulation on the bottom side. That is why Intertek said it was an agreed upon inhouse test procedure. p2000 can't even be honest in their testing.
Edited 1/7/2008 11:35 am ET by rich1
Rich,
The letter from Polar Industries you saw was published in the September 2006 issue of EDU. I was referring to the Back Page article in the August 2006 issue of EDU; that article quotes from the Intertek letter, which says in part, "We are aware that our name has been used in connection with misleading R-value claims being made by ... RR&D Enterprises ... These materials used Intertek's test reporty in a misleading manner..."
Energy Design Update also discussed P2000 in its June 2006 letter column.
Your queston on "apparanet R-Value" made me curious, so I researched it. Primarily it's termed "apparent" because that's literally true; AND, because of that the FTC has some guidelines on the R-Value claims of manufactures.
It's literal in the sense that it's an apx value per inch. If it were a true value per inch, one could assume that if you double the thickness of a product, you double it's R-value. Triple the thicknews, three times the r-value, etc. Reasonable, but as it turns out, not actually true. The overall r-value doesn't have a linear relationship to the thickness of the material...hence the term "apparent R-value".
There's a much more detailed explanation on wikipedia. Kind of a dry read but very interesting.
http://en.wikipedia.org/wiki/R-value_%28insulation%29
Sorry, Brutag. "Apparent R-value" has no scientific meaning, nor does it have any recognition from the Federal Trade Commission. It is an invention of advertisers and marketers.
ASTM distinguishes between "material R-value" and "assembly R-value." The R-value of a material is what is written on the package or product, and is regulated by the FTC. If you have an R-5 piece of foam, and install it on top of another R-5 piece of foam, the two pieces of foam have an R-value of R-10. These values can be added.
An "assembly R-value" is the R-value of a building assembly; one example would be a wall assembly consisting of gypsum wallboard, 2x4 studs filled with R-13 fiberglass batts, a layer of OSB, an air space, and brick veneer. This assembly has an assembly R-value that can be measured in a laboratory. Its assembly R-value can also be estimated by adding up the R-values of various layers.
The tricky part comes with air spaces. That's where marketers tend to exaggerate. The R-value of an air space in a building assembly depends upon the emissivity of the materials facing the air space. If one of the materials is highly reflective, like aluminum foil that has not yet been degraded by dust, then the R-value of the adjacent air space increases (at least until the aluminum foil gets dusty). However, the aluminum foil has almost no R-value. The R-value resides in the adjacent air space. (By the way, an air space without any nearby aluminum foil also has an R-value). More details can be found in ASHRAE Fundamentals.
If you have a one-inch air space bordered by a layer of shiny aluminum foil, that air space has an R-value. If you can build two adjacent air spaces in the same manner, the total assembly will have roughly twice the R-value of one air space. But in all cases, the aluminum foil has no significant R-value.
So, "apparent R-value" in marketing literature is usually a signal that it is time to notify the FTC of a probable violation of the Federal R-value Rule.
Edited 1/8/2008 6:08 am ET by MartinHolladay
Hi Martin, always glad to get educated on this forum. What I’ve posted is from another source I’ve read….not my personal opinion. So please respond in kind and “school” me on any areas where I’ve misinterpreted what I read …<!----><!----><!---->
Sorry, Brutag. "Apparent R-value" has no scientific meaning, nor does it have any recognition from the Federal Trade Commission. It is an invention of advertisers and marketers.<!----><!---->
>> Apparent is “ostensible rather than actual”, and I’m just suggesting it’s used as an appropriate description and also helps to avoid violating the FTC R-value rule. I’d bet the lawyers are just as responsible for this term as the advertising/marketing folks. ;-) Again, referring to the wikipedia article, it in fact refers to ASTM document C168 that R-value is a measure of "apparent thermal conductivity" (there's that word again) . It seems somewhat analagous to the gas mileage that car manufacturers state.
ASTM distinguishes between "material R-value" and "assembly R-value." The R-value of a material is what is written on the package or product, and is regulated by the FTC. If you have an R-5 piece of foam, and install it on top of another R-5 piece of foam, the two pieces of foam have an R-value of R-10. These values can be added.<!----><!---->
>> I understand, but isn't that still just a reasonable approximate and not an actual exact R value. .. From the Wikipedia article-- “The U.S. Federal Trade Commission (FTC)'s R-value Rule generally prohibits calculating R-value per inch of thickness. (16 C.F.R. 460.20.) The FTC explained the reason for this prohibition: Since the record demonstrates that R-values are not linear, advertisements, labels, and other promotional materials that express a product's thermal resistance in terms of R-value per inch deceive customers. The FTC further explained that references to the R-value for a one-inch thickness of the material will encourage consumers to think that it is appropriate to multiply this figure by the desired number of inches, as though R-value per inch were constant. (44 Fed Reg. at 50,224 (27 August 1979).)All values are approximations, "
An "assembly R-value" is the R-value of a building assembly; one example would be a wall assembly consisting of gypsum wallboard, 2x4 studs filled with R-13 fiberglass batts, a layer of OSB, an air space, and brick veneer. This assembly has an assembly R-value that can be measured in a laboratory. Its assembly R-value can also be estimated by adding up the R-values of various layers.<!----><!---->
The tricky part comes with air spaces. That's where marketers tend to exaggerate. The R-value of an air space in a building assembly depends upon the emissivity of the materials facing the air space. If one of the materials is highly reflective, like aluminum foil that has not yet been degraded by dust, then the R-value of the adjacent air space increases (at least until the aluminum foil gets dusty). However, the aluminum foil has almost no R-value. The R-value resides in the adjacent air space. (By the way, an air space without any nearby aluminum foil also has an R-value). More details can be found in ASHRAE Fundamentals.<!----><!---->
If you have a one-inch air space bordered by a layer of shiny aluminum foil, that air space has an R-value. If you can build two adjacent air spaces in the same manner, the total assembly will have roughly twice the R-value of one air space. But in all cases, the aluminum foil has no significant R-value.<!----><!---->
>>I think I got this. Is it fair to say here that the issue with aluminum foil and other reflective barriers is really an issue of conductive heat (measure by R-Value) and the ability to reflect radiant energy at the surface (i.e. emmisivity)?<!----><!---->
<!----> <!---->
So, "apparent R-value" in marketing literature is usually a signal that it is time to notify the FTC of a probable violation of the Federal R-value Rule.
>>Perhaps. But given the variables that effect R-value (convection, mass, humidity, etc), wouldn't it be more semantically accurate to use the ostensible description (ie. apparent) rather than stating a specific intrinsic value
Upon reflection, isn't the term "apparent R-value" imerely redundant. It's saying that you have an apparent value of an apparent thermal conductivity.
;-)
Brutag,
You are correct that, strictly speaking, very thin or very thick layers of insulation may have R-values that differ from an "average R-value per inch" multiplied by the number of inches. That's why the FTC regulates advertising of "R-value per inch." The FTC rules also simplify things for buyers, who see a single label with a single R-value on the product they are purchasing.
Adding up R-values -- two layers of R-5 insulation equals R-10 -- is, however, close enough for most of us and is fairly accurate.
Concerning some of the other items in the Wikipedia article, I choose not to comment, except to say:
1. Don't get me started about whether Wikipedia should be used as a source for technical information.
2. Misinformation on R-value abounds on the Web, and many distributors of insulation products have axes to grind. These distributors recycle rumors, falsehoods, and old R-value tales ad infinitum. The R-value article has been re-written many times at Wikipedia, by a variety of people with axes to grind. I have corrected falsehoods there in the past, only to see my corrections swept away by the next Web surfer or snake-oil salesman to come along and click his mouse. Caveat lector.
Thanks.
I'd agree that wikipedia articles need to be taken with a grain of salt and generally avoid quoting non-referenced material. I think the quotes I specifically used from there had references sources---FTC website and the ASTM.
I actually read the FTC web site to make sure the source was accurate and I would like to have read the ASTM document to see if it was quoted accurately.....I just didn't feel like paying the $36.00 they wanted to download a copy.
It's been an interesting excercise for me learning about insulation over the last few weeks. A rather confusing array of claims, truths, and half-truths out there.
I'm building my first house and have been doing extensive research into different materials. It's great to have a forum like this where different opinions can be solicited. Even better when they can cite acutual sources such as you did with the ASTM info.
The R-value of an air space in a building assembly depends upon the emissivity of the materials facing the air space.
Uhm, not to be argumentative, but only for clarity--isn't that only true for "still" air?
I could be remembering it wrong, too. It's happened before.
But, with just brownian motion in a masonry air space, doesn't the R value drop to whatever the K values of the two planes on either side?
This being Texas, I've wondered just how you properly 'score' just that, here where you can find McHouses with 7-8000 sf of brick veneer getting 300+ days of insolation.Occupational hazard of my occupation not being around (sorry Bubba)
Capn Mac,
I wrote, "The R-value of an air space in a building assembly depends upon the emissivity of the materials facing the air space." You asked, "Uhm, not to be argumentative, but only for clarity--isn't that only true for 'still' air?"
No. The best counter-example is the use of radiant-barrier sheathing (aluminum-foil coated plywood) as roof sheathing over an unconditioned attic. The product is installed with the aluminum foil facing down, toward the ventilated attic space. The foil is highly reflective (it has a low emittance), and therefore it reduces the transfer of radiant heat from the hot sheathing into the attic. The air in the attic is not "still" air; but the low emissivitity of the sheathing nevertheless reduces heat transfer.
The effect of emissivity on the R-value of an adjacent air space is detailed in Table 2 in Chapter 22 of ASHRAE Fundamentals.
You raise an important issue, however: the effect of convective currents (air leakage) on the thermal performance of building assemblies. This is a complicated but significant issue. Building scientists have developed modeling programs to try to quantify the effect of air leakage on the R-value of wall systems; the effects of such air leakage depend on a variety of factors, but it is safe to say that airtight assemblies almost always perform better than leaky assemblies.
Building scientists have developed modeling programs to try to quantify the effect of air leakage on the R-value of wall systems; the effects of such air leakage depend on a variety of factors, but it is safe to say that airtight assemblies almost always perform better than leaky assemblies.
Which is not much help to me while I'm slogging through ResCheck or ComCheck for my "compliance" <sigh> <G>.
My 'problem' with the foil-faced roof sheathing is that the sheathing winds up in direct contact with the rafters. The rafters then "gain" heat by direct contact with the sheathing. Down here around 29ºN, our attics don't need the heat gain the rafters represent by being "radiator fins." But, that entire concept goes against the "common knowledge" for attics. Makes it hard to advance 'smarter' answers, I can tell you.
I've got a local insulator who'd love to try using foil-faced batts transversely across the the bottom of the roof deck as a retrofit--but we can't find a customer with the right mix of finances and independance and project to give it a try. I'm not as "sold" on the elegance of it--we have many too many 4/12 hipped roofs making for some tough details to corner, and getting staples long enough to hold. Occupational hazard of my occupation not being around (sorry Bubba)
Capn Mac,
Well, even if you use conventional plywood or OSB sheathing instead of radiant-barrier sheathing, the top of the rafters or trusses will still be in direct contact with the sheathing. Conduction occurs in either case. Since we aren't talking about solid-aluminum rafters (I hope) nor solid aluminum sheathing, the effect of the thin layer of aluminum foil on the bottom of the sheathing should be negligible in terms of its effect on conduction from the sheathing to the rafter.
There is no doubt, however, that the aluminum foil significantly reduces radiant heat flow from the hot sheathing to other surfaces in the attic. The net affect in a hot climate will be to reduce attic temperatures -- a good thing in an air-conditioning climate.
Of couse, such sheathing will also reduce attic heat gain during the winter (for example, on a sunny winter day) in northern climates, thereby increasing the cost of heating energy for northern homeowners. That's why radiant-barrier roof sheathing doesn't make much sense up north.
significantly reduces radiant heat flow from the hot sheathing to other surfaces in the attic
But, the rafters and structure often wind up being of equal area for radiation, so the conductive gain "wipes out" the effect--at least in the real world examples I've been in.
The "circus tent" 9-12/12 McHouse roofs so in vogue with builders right now are even worse. The framing mass can be 2 to 3 times the mass of the sheathing--it's not uncommon to find the framing "sweating" anything that gets soluable around 130-140ºF (inks, resins, what have you) in those attics.
That's why I'd like to see what would happen if we could insulate over the whole thing. The trick of that being where to keep the mandated "ventilation plane." The simpler answer would be to let the foil face be the "ventilation plane" but, that introduces moving air which bolluxes the radiant "effect" a tad.
Really, our only sensible answer in this clime is to spray foam the kit-n-kaboodle. It's expensive, but it really, really works. At least out in the county--in town I have no idea how to get it passed by the BI. Occupational hazard of my occupation not being around (sorry Bubba)
<people's responses to pretty novice questions.>
wait - you're pretty?
That changes things - guys, we gotta' get some answers!
Sorry - can't help with the P2000. Sound s a bit like snake oil science, but that's just me.
Forrest
Hmmm - pretty is one word I have never heard used to describe me. Let's not start today either.
So we now know about that product. But for your project, maybe the Mooney Wall would be more to your likeing.
http://forums.taunton.com/tp-breaktime/messages?msg=65624.1