Spaceloft my only option?
Needing to get all the R value I can get in a limited space. From the cob webs you can see that this is an old house. Recently installed Cedar shakes with felt underneath over the 2×4 studs or mini rafters…
I think they call this a skip sheathing install of the cedar roof?
So, 3.5″ is all we have but we’d like to get to an R50 or thereabouts in our upgrade of this 1925 built home in Climate zone 4C.
Spaceloft seems the only option. With an R10 per inch. It comes in 10 cm thickness, 0.4″.
3.5 / 0.4 means close to 9 layers will fit in the 3.5 inch cavity. Plus one or two layers over top of the 2×4 rafters would get me to the R50 range.
The cost is exorbitant as far as I can see.
Installing it?
Cutting off the staple ends, putting up an airbarrier, going around the rafters following the roof under layment.
Housewrap is more a water resistant barrier than an air barrier I understand…
SO when installing this ultra expensive permeable Spaceloft what material is best to use to have it in an air tight, vapor open, cavity?
And than in 25 years when a new cedar roof goes on: better use short staples…
So in all: please advise alternatives to the “no other alternative?” Spaceloft…
Thanks!
Jan
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Replies
Jan,
I'm not familiar with Spaceloft.
Three and a half inches of closed-cell spray foam would give you about R-22.7. That's less than code minimum requirements.
The solution is to thicken up your rafters or to install several layers of continuous rigid foam under your rafters. You'll lose a little head room, but at least you'll have a roof that meets minimum code requirements.
Thanks Martin for the quick response.
So it all hinges on the big question whether or not Spaceloft is a scam or not... There are ZERO tests, confirmations, pro or against this material? Aerogel is what this is supposed to be based on. And that stuff is used by NASA. But this is riding on it's coat tail, scamming people?
The reason I am looking at this is that the loss of headroom is not acceptable in the rooms we are updating. It is already on the limit...
Jan
Jan,
If any loss of headroom is unacceptable, it's time to raise the roof.
Again, we're talking physics. Sometimes you just have to face facts.
Martin: the reason why aerogel can attain a higher R-value than the thermal conductivity of air is because of the Knudsen Effect: when a gas is trapped in very small pores, its effective thermal conductivity falls to below its thermal conductivity in other contexts.
That said, I am highly skeptical of the claims of this product because aerogel is a rigid material, basically a mostly-hollow brick made out silicon. This stuff comes in a flexible blanket. I have a hard time believing that it behaves the same as rigid aerogel. The way aerogel material works is by trapping an lot of air in billions of nanometer-sized pores. In a solid material, the integrity of these pores can be guaranteed. In a flexible sheet, how can it? If they're using flexible aerogel fibers or something (?), this would be an exceptionally delicate product. Curiously, I notice that there is no datasheet offered for Spaceloft.
Furthermore, aerogel is virtually transparent to radiative heat transfer. Even if you were using real aerogel here, you would need a radiant barrier or two, especially in this application because most of the heat transfer from roof sheathing/decking to what's below it is radiative.
But let's say I'm wrong that this stuff really performs as advertised. The best price they offer is $95/inch thick/square foot. By contrast, conventional insulation materials are literally in the ballpark range of to 100 times less expensive. at 3.5" thick, you're paying $332 per square foot of roof. You could, like, demolish the house and build a whole new one for that price given an average-sized attic.
It sounds like you're going to have to compromise somewhere: losing ceiling height, re-doing your cedar shakes to put foam over the decking, or accepting a very low amount of insulation.
Finally, is this even a good idea? cedar shakes really like ventilation. If you block that off with a properly-done insulation job, you're reducing their drying capacity and reducing their lifespan.
This is the datasheet Aerogel has on their website:
http://www.aerogel.com/products-and-solutions/all-insulation-products/
Indeed it all sounds too good to be true. But it also sounds "too good to be true" when this is a huge big professional scam.
It is an historical home where one wants to retain the character. And that can get at times difficult and costly...
Regarding the breathing of the shakes Nate. The picture shows that these shakes are installed on laths. Skip sheating is the term I think? There is nothing better to have shakes installed on. The insulation below will not affect that. Spraying polyurethane underneath separated by some barrier will hinder the ventilation more than what I would get from installing this Spaceloft plus again some air barrier.
Nowadays code does not allow this way of installing shakes. Must be on plywood... We just had cedar shake installed with metal plates underneath for that purpose: wavy plates that keep the shakes for touching each other and greatly increasing ventilation. A man in Canada makes these plates out of his garage. GREAT product..
Pic attached.
Interesting point about your radiation remark...
Their Cryogel product I think comes with a radiant barrier attached. Similar properties over Spaceloft. So regarding your point I would need a layer of Cryogel on each side to have two radiant barriers...
That is if I go this route. But strange that there are no independent verifications on this Spaceloft and Martin did not know the existence up until this question...
It is not the entire roof that will need this expensive aerogel material so volume is limited and the dollar amount is clear to me. So let's assume all is good with Spaceloft: how best to install this between and over the rafters. OR this is just out of anybody's scope and I'd just have to order some and let you guys know how it goes as I go along.
Thanks
Jan
Cryogel has a vapor barrier attached to it... not a radiant barrier..
http://www.aerogel.com/products-and-solutions/cryogel-z/
A variety of Aerogel products have been developed over the years. I'm familiar with silica Aerogel (or Nanogel) glazing products that claim R-8 per inch and are designed to be translucent.
I've also heard of an Aerogel coating, Aerolon, that claims to have an R-value of R-4 per inch.
Spaceloft (with a claimed R-value of R-10 per inch) is new to me. I'm always skeptical of R-value claims that exceed R-7 per inch, but the high R-value claimed for this product may be possible. I'd want to see some third-party lab reports before I believed it, however. And if the product costs $332 per square foot, it seems fairly irrelevant to the everyday concerns of residential builders.
At $95/sq ft inch, 10 square feet costs about $3320. Suppose you have 5000 HDD/year. With spaceloft you lose 34k BTU/year through that square foot; with R-5 insulation you lose 68k. So you have spent about $3k to save 34k BTU/year. If you instead put that $3k towards PV, you'd conservatively get 750 W, which, again being conservative, would net you 750 kWh/year. You could use that to run a heat pump but even if you just used it for direct electric heat, that would give you 2560 kBTU/year, or 75X greater bang for your buck.
So the price is about 75X higher than it should be to be cost effective.
I generally think it's worth considering installing new energy efficient technology even when it's not quite cost effective, but this so far away that it doesn't seem even worth considering.
Jan, if money is no object, I would expect that it would be less expensive to completely demolish the roof and rebuild it in a manner that both preserves its historic character and is also super-insulated.
Honestly this roof does not seem like a good candidate for cathedralizing. To do it right, you need either 1) foam between the sheathing and the roofing, 2) ventilation channels under the sheathing or 3) spray foam under the sheathing. 1 would seem to be out because you want to preserve your non-code-approved roofing installation. 2 is problematic because you don't want to lose any ceiling height and your rafters are very shallow, so you would be highly R-value limited. 3 is impossible because it will interfere with the roofing. Given these restrictions, I would say that there appears to be no way to safely and sanely do what you want, Spaceloft or no.
If you don't like that answer, you can also try option 2 and make the best of it. 2" ventilation channels will leave you with 1.5" of Spaceloft between the rafters, which will yield maybe R-12 when you take into account the thermal bridging of the rafters. That's pretty awful whole-ceiling performance, and it will cost you $142 per square foot. For that price, you might as well remove the entire roofing assembly, raise the walls by 6", put it back in place, and use that extra 6" to put foam under the rafters.
Yes Martin, independent verifications would be extremely helpful... That is where I also got a touch leary, hence my posting. And indeed for the average builder this product is off the scale to be relevant price wise. Notice a link they posted on their website regarding insulating a shipping container converted for a residence. Space is an issue there and a steel box is a bad start, so for that it could be useful OR build a house for the same price!!
But back to my situation: redoing the roof is the only alternative and gets me I fear very close to the same pricetag WITH a major disturbance in the yard as we have a fully established garden now. So adding all that up: this Spaceloft use could be justified. The "redoing the roof" suggestion means redoing both sides of the house to match the increased height now. And we are talking a lot of inches. It WILL affect the character of the house.
So since this Spaceloft is permeable to air I need good solid advice which materials to specifically use and how to create an as airtight "housing" around this material. Again without using up any inch of space. Simple Tyvec or housewrap in general may not do?
So in all, it will be a bit of an install job, with the multiple layers that will have to be applied. But so far all, to me, steers away from roof redo. That was 20.000 dollars 5 years ago. So I'd be looking at 20.000 PLUS insulation PLUS a yard mess and damage.
OR go with Spaceloft.
When I can get it, as it seems to be in short supply.
Thanks!
To Charlie:
The PV suggestion is hard for us to use. West facing roof only, nothing south. Plus trees taking away morning and afternoon sun. Plus adding brute energy power only reduces our energy bill but does not help the comfort level...
Thanks
At $95/inch thick/square foot, $20,000 buys you 210 square feet of Spaceloft at one inch thickness (materials cost alone, no shipping, installation, or other costs included) and gives you only R-10 between the rafters, probably about R-8 overall when you take into account the thermal bridging from the rafters. I assume that your attic has more than 210 square feet of roof space in it and that you want (or are required to have) better than R-8 insulation.
You need to run these numbers. The cost is stratospheric. 3 inches of Spaceloft spread across 700 square feet of roof costs $200,000. It's your house and your budget. If you want to put tens to hundreds of thousands of dollars into getting a poorly-insulated roof, you're welcome to do it. But to me, this seems like a crazy proposition. You seem to be getting yourself tied in knots because of the limitations you've set for yourself. Sometimes it's time to admit that those limitations either preclude any good options or need to be removed. If you can lose a few inches of ceiling height, you open up your options tremendously. Another idea: if you need more space in this house, why not build a ground-floor addition instead? You can build it such that it preserves the architectural character of the house and design it to have very good insulation, and it will cost orders of magnitude less than this attic cathedralization idea and be a lot easier to find qualified people to do the work, too.
Jan,
If you are committed to your plan, install some cardboard or housewrap between your rafters, followed by R-20 of spray foam, and live with the imperfect thermal performance of that type of assembly (assuming, of course, that your local building department doesn't require a higher R-value).
Martin, (and others)
The local minimum roof R value here in 4C is 38 as far as I know. We may be allowed to do what the heck we want as it is a renovation project but so far all goes through inspections. Regardless of that: we are going to have radiant heat in the house and the radiant engineer also demands good insulation for that to properly work.
That is where Charlie's remark of "just get cheaper energy into the house would be more cost effective" is only half the problem solved.
Well, I accurately calculated my surface area, which is of course crucial in this venture! All the "200.000" and "tens of thousands" remarks, naturally, scared the pujeezus out of me! "Would I have been so misjudging this" was going through my head...
155 square feet is that particular roof section.
With their bulk calculator I come to around the $900 dollar per layer. 3.5" will hold 8.89, 10cm thick blankets. 9 layers times $900,- is $8100.
Add two layers to go right across the rafters for each $1000,- or maybe a touch more as now I have no space loss due to the loss of the rafters and I come to the still hair raising $10.100 mark.
Yes it may become the most expensive cedar shake roof on the north american continent, but the alternative is way more: redoing and re-insulating the roof from the outside PLUS the inside.
Back to advice help on how to best first layer these roof cavities under the rafters. What is the most air tight but vapor open fabric possible? MemBrain? Paper layer the wood surfaces first to protect damaging the MemBrain? Or pre sanding these rough surfaces for that...
When I get the confidence I can install this Spaceloft securely in an airtight configuration I must track them down for their R value claims. At that is the sole last important link that is missing....
Jan
So that's $15/board foot (board foot = square foot inch thick), not that $95 that Nate reported and I used. That brings is back into the realm of a little eccentric, as opposed to completely wacko. I'm comfortable with a little eccentric. My previous cost-effective calculation changes to 12X as expensive as it should be, rather than 75X.
The extra heat loss from that, at a 60 F temperature difference (We still don't know your climate, so that's a guess) is only 265 BTU/h less than you'd get with an R-5/inch solution. The radiant engineer shouldn't call himself an engineer (or radiant for that matter) if he thinks that an extra 265 BTU/h is going to undermine his design. That's less heat loss than a 25 square foot high-quality U 0.2 triple-pane window.
But I've seen people spend more than $10k without saving any energy at all, so if you want to spend $10k and save 265 BTU/h, that's great, as long as you understand that it's not necessary for your heating system to work.
Next question is how you can use this stuff without moisture problems. Very similar to if you used fiberglass, which is a bad thing against a roof. The good news is that your roof itself is unusually high permeability, so you can probably get some drying upwards. So I think that with a smart vapor retarder like MemBrain or Intello you'd be find. I think Intello is a little better if a little more expensive, so that is probably the way to go.
Roxul's Aerowolle only gets you around R-8 per inch, and that's using an interwoven aerogel/mineral fibre mix.
Does this carry any weight?
http://www.buy-aerogels.eu/image/data/pdf/ETA%20-%2011_0471.pdf
and
http://www.buy-aerogels.eu/image/data/pdf/Spaceloft_DS.pdf
and
http://www.aerogel.com/_resources/common/userfiles/file/Data%20Sheets/Spaceloft_Subsea_DS.pdf
...and seeming third party testing here:
http://www.buy-aerogels.eu/image/data/pdf/Spaceloft_Technical_Guide_1%200-EU.1-18.pdf
and
http://www.buy-aerogels.eu/image/data/pdf/Spaceloft_Technical_Guide_1%200-EU.19-53.pdf
Bill,
Those links are definitely helpful. So I have no reason to doubt that this product has the claimed R-value.
However, cutting up this expensive insulation and fitting it between rafters seems wasteful, since the resulting assembly still has thermal bridging through the rafters. Once the thermal bridging is accounted for, the improved performance compared to spray foam is minor, and certainly not worth the investment.
One more thing to consider - work safety. I considered using aerogel mats in the side walls of dormers, but our carpenter wasn't keen on dealing with the stuff - the handling recommendations are not too far away from asbestos...
Martin, I agree. This should also carry weight - the product is not intended for residential use. From the data sheet:
"Spaceloft® Subsea is provided for subsea PIP users in a prepackaged form to permit quick installation."
and
"Information presented herein is nominal and may not be representative of the actual product performance of a specific material. Any and all warranties, either expressed or implied herein, are disclaimed. All products or materials supplied, including any recommendations or suggestions, must be evaluated by the user to professionally determine the applicability and suitability of this product for any particular use, including for use in subsea pipelines. Values in this document should not be used directly for specification or design purposes.".
Bill,
Thanks for finding independent info regarding it's true R value!
The product is intended for residential use among other uses.
http://www.buyaerogel.com/product/spaceloft/
"Aspen Aerogels’ Spaceloft® is a flexible aerogel composite blanket designed for insulating buildings and apparel. With a thermal conductivity of 14 mW m-1 K-1, Spaceloft is approximately two and half times better insulating than Styrofoam®. Great for home insulation, winter clothing, science projects, and any application where thermal insulation is needed and space is at a premium."
You seem to be looking at the "subsea" version's datasheet, I cannot find that particular info on Aerogel's website though. But they mainly use Aerogel products in industrial piping applications. But as mentioned and pasted in above they clearly recommend use of this Spaceloft in residential buildings. Also that it is inert and can be landfill disposed. THAT however does not clear it from having similar characteristics as asbestos when cutting it up. I truly wonder about this though. Would this be allowed on the market after our asbestos ban and knowledge. AND as it is used in APPAREL... I truly doubt that there'll be any asbestos related issues. Working with ANYTHING that gives of dust particles like fiberglass: wear a dust mask! But that is common sense.
Regarding Martin's install issues and degradation of the qualities of this Spaceloft. The cutting up and installing between the rafters will have issues with any insulation material even polyurethane. But regarding thermal bridging: I intend to put two layers continuously below the rafters. To try and get as close to R38 as I can...
Can I put Membrain on the cold side? For getting better air sealing this way.
Charlie mentioning Intello Plus being "better". According to the specs that I got via Dana Dorsett: MemBrain breathes way better. Opens better at lower relative humidities.
Intello Plus may be stonger so in that vain I am contemplating to put Tyvek in first as more of a protective layer between the rafters and the MemBrain. Than Spaceloft. So from outside to inside: Tyvek (or something better?) MemBrain, insulation.
Could not find anything on Roxul's AeroWool. I suspect it is in development phase only?
Jan
Intello is less permeable than MemBrain. I was thinking of it on the interior side, not the exterior. That would retard vapor getting into the insulation more than MemBrain does, but I think either is fine.
I don't think it's needed on the exterior. If you want to get better air sealing there, I think ordinary housewrap is fine, maybe better.
Using it to block thermal bridging is the one place where expensive insulation like this could really be worthwhile.
Housewrap is mainly a water resistant barrier than an air barrier, I thought.
That is where I am going to get this expensive permeable insulation into an airtight, vapor open enclosure: for it to WORK.
"Thermal bridging is always good" is what our radiant engineer always says and that of course is very true. The insulation being expensive or cheap is irrelevant. It is just good, any R value you put there. It really does it's work there.
For Martin regarding his remark: 'Once the thermal bridging is accounted for, the improved performance compared to spray foam is minor, and certainly not worth the investment."
I am investing in space saving. I do not have the multiple inches to add for regular insulation. My back is against the wall, or in this case: the ceiling...!
Thanks
Jan
Regarding the "asbestos like" handling recommendations: The aerogel dust is extremely hygroscopic and acts as a desiccant, drying tissue it comes into contact with. It is otherwise not dissimilar from fiberglass dust, and lacks the properties of asbestos that create the long term health risks. The handling recommendations are similar to those of of fiberglass.
Fiberglass is already unpleasant enough that I wouldn't be eager to work with particularly unpleasant fiberglass, but there's presently no evidence to suggest that aerogel dust is any more hazardous than the other dusts encountered in construction.
The bulk price is better, but I still think this is ridiculous. Here's why.
At its core, Spaceloft even purchased in bulk is R-10 per inch @ $15/inch, materials alone. closed-cell spray foam is R-7 per inch @ maybe $1.20-1.50/inch, all-inclusive price. CCSPF is 30% worse for 1/10 the price. Let's break it down for your specific situation:
Your idea: 3.5" spaceloft between the rafters + 0.8" spaceloft over them. Assuming the rafters take up 15% of the space, the total R-value of this assembly is (3.5*10*0.85)+(1.2*3.5*0.15)+(0.8*10) = R-38.38.
...And the cost of the materials alone is $10,000, not including the vapor retarder and the labor for this work if it's hired out.
Now let's look at Martin's proposed alternative of cardboard and CCSPF between the rafters, and let's even add 0.8" of Spaceloft over them to reduce thermal bridging. That alternative assembly is (3.5*7*0.85)+(1.2*3.5*0.15)+(0.8*10) = R-29.45.
And the cost is $2,480 (155 sf @ $11/sf for the 0.8" Spaceloft + $5/sf for the 3.5" spray foam).
So for less than 25% the price, taking Martin's advice and adding only a little bit of Spaceloft would get you 77% of the R-value. That seems like a no-brainer to me. The differences between R-30 and R-38 are NOT worth paying another $7,500 IMHO. Comfort-wise, if this is conditioned space, you won't feel the difference. But it's your money!
So R value is not that important anymore. Code is not even minimum requirement but irrelevant?
I fully understand the frowns regarding the cost.
But understand my frowns regarding polyurethane:
https://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/weighing-merits-spray-foam-insulation
Reading the comments, it's just a huge question mark why it is not banned from talking about this stuff on GREENbuildingsadvisor... It is a very dubious product. Sure a quick and easy fix. But with huge downsides to it. Add the recycling problems to it and it's a clear no go for any conscientious person.
As is rigid foam...
Just my opinion on that.
Thanks
Greener-than-thou debates are insufferable. R-value is important, but so is cost. How long does it take you to earn an extra $7,500? How many more hours of commuting to work to earn that money is the result? How is the carbon emissions of that car use balanced against the source emissions saved by using less energy? And what's the environmental impact of making aerogel? How recyclable is it? Etc. It is impossible really to judge any of these options as "greener" than the other when you're already in the ballpark of "pretty good." I'm no fan of foam either, but you've painted yourself into a corner with your long list of requirements. Environmentally-friendlier cellulose and mineral wool would be possible if you could lose a few inches of ceiling height, for example. But if you want to go with the Spaceloft, go ahead! I just question the cost-effectiveness. The marginal cost of getting another R-8 into your roof appears to be $7,500 or more. That wouldn't be acceptable to me; I would rather use that money to add solar panels or put more insulation in a part of the house that's even more lacking like maybe the basement walls, but if it's acceptable to you, by all means, make it so! There's room in the world for all types of people.
I have no space Nate...
I have no space...
You think I am going with Spaceloft for fun?
Another thing...
Polyurethane under a cedar shake roof?
You smell the other problem with that?
Have you read the other postings comments section at all?
Spaceloft has none of the Polyurethane problems. Polyurethane adds structural strength. That is to only good thing about it as far as I can see.
Martin's suggestion involved cardboard under the roofing, preserving some air space there and preventing the foam from touching the sheathing boards or the tar paper. Furthermore, the cedar shakes are not vapor-tight, preserving outward drying potential. I see no reasons why this might fail.
Like I have said, you really seem to be trying to fit a round peg into a square hole. You have practically no space for insulation yet you want a well-insulated roof. You can't lose any more than one inch of ceiling height and finishing the attic is crucial. There are many ways out of your conundrum. One is to go with Spaceloft, which has the downside of extremely high cost for small marginal benefits over alternatives. Another is to go with CCSPF, which has environmental drawbacks. Still another would be to accept a small reduction in ceiling height in exchange for being able to use much cheaper and more environmentally benign materials such as cellulose and mineral wool. Another is to use those more environmentally-friendly materials and accept a slightly lower R-value than you might prefer. Still another is to build an addition onto another part of your house rather than cathedralizing and finishing the attic.
You've got lots of options, you just don't like any of them, and you are focusing on the highest-cost one because it gets you closest to what you actually do want, but IMHO you are putting outsized focus on the benefits and not enough on the drawbacks of quadruple or more the cost of the next best alternative. Maybe you're incredibly rich, in which case the cost differential is negligible to you, and if that's true, I understand your position: why not spend what you need to get the best if you can afford it? But if you are not super rich, I think it makes sense to take cost into account as well. 4" of rigid mineral wool under the rafters + cellulose cavity fill with a vapor retarder would get you R-28 and would likely cost you less than $1,000 for that space (much less if you do it all yourself) and be the most environmentally benign of all. The Spaceloft option costs more than 10 times as much and gives you an extra R-10. Ask yourself if it's worth paying $9,000 for 3 more inches of ceiling height and 36% better thermal performance. If it is… do it! If it's not… then it's time to stop agonizing and make a compromise.
Jan - the link you provide (comment 21) mentions the uses of Spaceloft as "Great for home insulation, winter clothing, science projects", but the link to datasheets for material with a conductivity of 0.14 W/mK (R10 per inch) is an undersea pipe product. Hardly residential. If you proceed, be aware that you are probably in the "science project" category.
The Spaceloft product rated for "Ambient temperature walls, floors and roofs in commercial, residential and institutional buildings" has a lower thermal resistance (R8.3 per inch) and no datasheet describing the application.
If the product under consideration is rated at R-8.3 per inch, the logic of using it is weaker than ever.
Yes Martin, the info from Bill, when correct is making it all weaker.
But it is still ahead in many ways over "the rest" to use. We have the money to do it but do not want to waste it either!
Time to contact them and see what they have to say regarding Bill's latest contribution.
Thank you for that Bill!
I have via Aerogel, good communication and email contact with them, tracked down their distributor and am in the final stages now to go with this Spaceloft. It's been rebranded as ProLoft. Can anyone with more knowledge than me help with verifying that the stuff is what it is cracked up to be. I attach their independently verified datasheet. Martin already eluded on it that R10 was possible. But Bill mentioned it was related to Subsea.
This is the Proloft, Spaceloft specific testing paper:
Thanks
MMmm, cannot attach a .pdf document??
Jan,
Attached is one of the reports that evaluates the performance of Proloft.
Advanced Insolutions Inc. is the owner and distributor of Proloft. I'm the Vice President of Advanced and would be happy to answer any question. Please visit http://www.advancedinsolutions.com for more info. We also have had Intertek do third party testing for Proloft. Please feel free to contact me [email protected] 250-551-3200 (cell)
Also...Proloft is $5 USD sq/ft @ 3/8" thick - $15 USD sq/ft/inch
So the report says R 9.1/inch is the data coming out of the instrument, but per ASTM D1622, they also calculated the R-value using a different thickness, and the data comes out as R-10.2/inch. I'm not familiar with the details of ASTM D1622, but it seems a little fishy to use the heat flow data from the instrument at one thickness, and then use a different thickness in the measurement, so unless I hear a good reason to go with that mixed approach I'm inclined to call it R 9.1/inch.
Also interesting are the steel wall assemblies shown on the web site, with patches of this stuff inserted to mitigate thermal bridging in one of the two cavities. The asssemblies around the R16-R18 range. That is better than steel stud walls without the thermal break, but it would be more interesting if there was a way to get to R30 or R40.
Charlie: Intertek is obligated to report all of their testing. The reason they gave two different results is because the material has ridges and the C518 machine was getting air pockets on the surface of the Proloft which was lowering the R-value. These results are an average of multiple samples tested.
The steel wall assemblies were modeled and tested by Alex McGowan from Levelton Consultants Ltd. in Vancouver, BC. To achieve an effective R 30 - 40 in a steel stud wall is virtually impossible without creating an extremely thick wall assembly. Building professionals are having a hard enough time meeting ASHRAE 90.1 2010 standards for commercial buildings.
I'm personally driven to source and provide products to the building industry to keep up with the rapidly changing codes and standards. The codes are changing faster than the industry can keep up, which in turn is kind of a good thing. All buildings to be net zero would be best case.
Martin, and others.
Any verdict on the R rating of this Proloft, Spaceloft?
Where is the truth on this.
Is it 8.3, 9 or 10.2. OR are all numbers off?
R value being relative as it is, it is still good to have this info. And also... the independent data sheet is not added to the Q&A posting, for people to pick up on it there.
Thanks
Jan
Jan,
Here is the link to the evaluation of Proloft Aerogel Blanket.
The document notes, "R/inch using instrument measure thickness is 9.1 R/inch (Hr-ft2-ºF/Btu/in).
R/inch using ASTM D1622 measured thickness is 10.2 R/inch (Hr-ft2-ºF/Btu/in)."
I'm not sure how important the discrepancy between these two methods of measurement really is. I can't really imagine any application where the difference between R-9 per inch and R-10 per inch would be significant enough to matter.
Remember, when you install any type of insulation -- fiberglass batts, cellulose, or spray foam -- installed R-value per inch can easily vary +/- 10% from published values.
Thanks Martin,
I am fully aware of the relative quality of any R value. I just needed guidance in the translation of the heat loss numbers. BUT when you'd come up with Proloft being on the 8.3 side for instance, with this price tag, it would be important info to have regardless.
Installation advice.
Full WarmBoardR on the inside, so no venting to be had there. Our cedar roof installed as skip sheating is TOO vented. So best way to (no foam) seal this as airtight as can be: Tyvek for protectection around the rafters followed by MemBrain. Tyvek to protect the MemBrain.
OUTward venting in climate 4C. Replacement of cedar roof (in 30 yrs we hope) will probably get plywood sheathing overtop of the skip sheathing, and will then hamper the ventilation to a degree. With 0.5" plywood and limited length staples it makes installation safer: to not penetrate the Tyvek and Membrain down the road.
Jesse was helpful to advice the use of PL200 or PL400 construction adhesive to hold the Proloft in place during installation. I would need some help probably to temporary hold things in place, like a construction glue. Same for the Tyvek and Membrain. Stapling the Tyvek(?) but spot glueing the MemBrain?
Thanks
Jan
Hi, Jan. I am where you were five years ago regarding aerogel insulation. Old house. Limited space for insulation in attic ceiling. 100% anti-spray foam (I have aversions to a long list of common building materials, and spray foam insulation is high on that list). I was planning to blow sheep's wool insulation but read a PETA article that sent me into an ethical tailspin. In short, identifying the right insulation has been exasperating. So...five years later, are you happy with the aerogel insulation? Appreciate any insight.