Raycore panels
Last Post 30 Jan 2013 03:30 PM by Dana1. 16 Replies.
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Sal123User is Offline
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13 Apr 2012 05:47 PM
I am in the planning phase of a 4,500sf home in the N East trying to to achieve a passive house-like result in regards to insulation. For the walls I am considering SIPS vs Raycore panels vs stick with blown insulation in the cavity and possible additional exterior rigid poyiso panels. I want to acheive the highest R-value (somwhere in the high 30s to 40s) at the least expense, novel concept ay? I am trying to get info on their correct use. This has raised many questions, of which; 1. Given that Raycore has a foil barrier on both sides, and relies on sheathing (OSB or plywood)does it matter how one ultimately configures the wall? Using standard OSB/plywood, without applying hygrothermal modeling programs like WUFI, it seems the dew point would fall on the inside surface of the exterior sheathing. Does this need to be taken into account to insure the wall has enough opportunity to dry under normal conditions? Can a structurally insulated product such as Dow's SIS be applied instead of OSB? Will it affect the drying ability of the wall? Could another layer of 1" polyisocyanurate rigid insulation be applied on top of the SIS or OSB? If its OSB, does this configuration hinder the wall's natural drying making the OSB the sink for all the trapped moisture in a wall like this leading to ultimate failure? The latest recommendations from the building science literature recommend the concept of "outsulation" - apply as much insulation as external on the wall as possible. Does using Raycore present a problem in some situations as described above? I would like to thank anyone who will take the time to address this issue and greatly appreciate any information you can offer.
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19 Apr 2012 12:40 AM
Sal,

You will not achieve a passive house standard in the R-30 to 40 range in the NE USA. You need more.

None of the systems you have mentioned deliver the highest R-value / dollar / square foot of wall. I will attach a chart comparing the different systems I have worked with that I prepared to help me develop perspective. The chart is made to compare wall systems that can be used in a passive heating and cooling construction approach. In severe weather situations it is not possible to build to passive house standard without high internal thermal mass. Mass has a similar relationship to efficiency as super insulation does.

I think you might want to think about additional systems. This bulletin board limits the resolution of drawings. If you send me your email I will send you a higher resolution chart that is easier to read.

Brian
ICF Solutions
Engineering, Designing, and Building Passive, Net Zero, Self-Heated, Self-Cooled, Self-Electrified, Low Cost Homes
Basic shell starting at R-50 Walls, R-80 Roof structures. for $30/square foot
(360) 529-9339
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19 Apr 2012 12:26 PM
Posted By Sal123 on 13 Apr 2012 05:47 PM
I am in the planning phase of a 4,500sf home in the N East trying to to achieve a passive house-like result in regards to insulation. For the walls I am considering SIPS vs Raycore panels vs stick with blown insulation in the cavity and possible additional exterior rigid poyiso panels. I want to acheive the highest R-value (somwhere in the high 30s to 40s) at the least expense, novel concept ay? I am trying to get info on their correct use. This has raised many questions, of which; 1. Given that Raycore has a foil barrier on both sides, and relies on sheathing (OSB or plywood)does it matter how one ultimately configures the wall? Using standard OSB/plywood, without applying hygrothermal modeling programs like WUFI, it seems the dew point would fall on the inside surface of the exterior sheathing. Does this need to be taken into account to insure the wall has enough opportunity to dry under normal conditions? Can a structurally insulated product such as Dow's SIS be applied instead of OSB? Will it affect the drying ability of the wall? Could another layer of 1" polyisocyanurate rigid insulation be applied on top of the SIS or OSB? If its OSB, does this configuration hinder the wall's natural drying making the OSB the sink for all the trapped moisture in a wall like this leading to ultimate failure? The latest recommendations from the building science literature recommend the concept of "outsulation" - apply as much insulation as external on the wall as possible. Does using Raycore present a problem in some situations as described above? I would like to thank anyone who will take the time to address this issue and greatly appreciate any information you can offer.

The fact that Raycore has a foil facer on the interior side as well as on the exterior, the dew point of the interior air is irrelevant-  the applied sheathing has not one but two class-I vapor retarders between it and the interior air, as well as air-impermeable insulation. You could keep the interior a 60% RH all winter and not produce a measurable change in moisture on the exterior sheathing.

If you sheath it with OSB on the exterior you need to allow for a drying path to the exterior, since the facers prevent drying toward the interior.  An inch or two of XPS over the sheathing isn't a problems as long as you're not trapping moisture between the siding and the XPS. (Leaving at least 3/8" of vented rainscreen gap between the foam & siding would be a good idea.  Using 1x furring gives you twice that, and  better fastener retention for the siding.) 

Going thicker than 2"  with XPS would bring the permeance to the exterior to under 0.5 perms. But with fiberglass-faced iso you can go with any thickness, as long as you keep it to one layer.  Foil faced iso is out of the question, since it would trap the OSB between foil layers, a classic moisture trap.

The fact that Raycore panels are thermally bridged by 16" o.c. timber elements, the ~R7/inch of the polyurethane is largely wasted, with heat transfer dominated by those elements, and the website R-value references are somewhat deceptive. The "R26" of a 3.5" version works out to about an R12 average (which includes the sheathing, siding, and interior gypsum) at typical timber-fractions, less than half the stated R between the  wood elements   The R42 of the 5.5" version  works out to about R19 with the wood fraction factored in, if you include the top & bottom plates.  They do some thermal breaking on the 12" o.c. staggered-stud versions, which would be far preferable.

The website also talks up the thermal radiant-barrier value of the foil facers, but unless you allow at least 3/4" of air-space between the facer and the next element in the stackup that factor is negligible.

I'm not saying "don't use them", only cautioning to model them correctly, as performance will be roughly half what is implied by the numbers on their website.
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20 Apr 2012 09:38 AM
~passive-house-like----

Hello:

If ever it can fit, there are solar screen-air/ well-filtered panels that run 30+ years later with little filter changes of any maintenance at all seen in Dayton Ohio.

From as simple as leaning against a back yard wall to accepting angles from 40-deg to 60-deg tilting...

A peanut refrigerator-cooler sealed axial fan-motor, 6" fan ~ 40 - 85 watts; galv Alum or SS super thin 30-gau, box, 1.1/2" poly foam insul backs and sides
and
500-deg OEM baked grey window screens which pickup sunlight at various angles very nicely:

Controls
$ good 15 buck stat, and 2 snap discs buried in electrical approved silicone glue in the panels.

+ some bi-metal top panel piece for 180-200-deg auto venting is OK but I think that could be improved after recirculating air to water-heating Btuh's  is "full".

no solar tax credit unless system is rated -+ approved etc, but the local tinner can make those boxes from 10x4 sheets rather quickly

a clear layer of TFE and the Solar glaze   and screens are all about 3/4" apart to 1" spacing for 3 screen layers.

6 collector was too much for a standard insulated 1970's 1700 sq ft ranch we made work with high return-airs and registers that threw ceiling diffused air straight down to the floor in a "column" for vertical air destratification, stabilizing the rooms.
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20 Apr 2012 11:05 AM
"I want to acheive the highest R-value (somwhere in the high 30s to 40s) at the least expense..."

The least expensive R40-ish wall buildable by contractors that have no experience with super-insulation, is usually a 2x6 studwall with cellulose cavity fill (~R14 after thermal bridging of the framing is factored in), detailing the exterior sheathing as a primary air barrier, with 2 layers of 2" rigid polyiso (foil faced or fiber faced, also seam & edge sealed), which adds another ~R24-R26 to it for a total well north of R35. The foam is held in place with 1x or 2x furring, long-screwed to the structural wall (with the fasteners 24" on center to minimize thermal bridging), and the siding is then hung on the furring. A foil facer on the iso facing the gap adds another ~R2 to the average performance of the assembly. A general explanation (and links to many of the detailing aspects) of this approach can be found here:

http://www.greenbuildingadvisor.com/blogs/dept/musings/how-install-rigid-foam-sheathing

Dealing with the thermal bridging at the transition to the foundation & foundation insulation is an important detail for any high-R wall (including SIPs) necessary to keep the performance high. With an exterior foam approach, building the foundation walls with insulated concrete forms an aligning the wall-foam with (or slightly exterior to) the foundation foam gives it a continuous thermal break, with no fully bridging concrete or timbers.

Contractors & architects well versed in Larsen Trusses and double studwalls can sometimes get there for less money with all-cellulose or predominantly cellulose insulation, and that's usually the better way to go for much-higher R walls.
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20 Apr 2012 07:49 PM
For the Raycore panels I would say that the R values at 7.5 per inch are a little high. The panels do not eliminate thermal bridging so the whole wall r value will be much lower. The appliead radiant barrier will likely be of no value as I would assume drywall would be applied to one side and OSB on the other. The corner details show a double top plate so there would be aditional thermal bridging. I see needing osb to prevent racking and for a sheer wall. I think you should look at other options to achive a high R value and for durability.

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21 Apr 2012 11:47 PM
Thank you for your replies.
I was initially thinking a 2x6 stud wall, blown closed cell foam, Dow's SIS - structural insulating sheathing - and 2 staggered, taped 1" foiled rigid polyiso. Was hoping an alternative would prove less costly with the same if not better R- value.
Am getting prices for a few configurations, will post the numbers.
I continue to welcome any input/suggestions/comments,
Thanks again
Sal123User is Offline
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23 Apr 2012 02:58 PM
We're going with stucco and stone veneer exterior. I am looking into the dynamic of stucco/stone exterior in superinsulated walls. I like the idea of the continuous thermal break of an exterior foam approach, both ICF in the foundation and a foiled poly-iso as exterior product. But how do you fasten stone to the exterior wall if your ply or OSB is under 4 inches of foam? Even at 2 inches of foam? Am investigating options.
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23 Apr 2012 05:38 PM
On another thread one homeowner said he uses the AIRTap Ht P Domestic Hot Water heater 9-10 months a year with dehumidification helping.
GE , Whirlpool. Would you instal any/ Ze, D1, others? Thinking about moisture and etc, on tight homes...

Since so many DSH on GT need cleaning, perhaps service drains and cleaning with vinegar may be good for the Air:HW units, too. Rheem techs claimed 5gal-vinegar-30-minutes, through the larger instant HW Heaters was 'spec'.
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24 Apr 2012 02:07 PM
Posted By Sal123 on 21 Apr 2012 11:47 PM
Thank you for your replies.
I was initially thinking a 2x6 stud wall, blown closed cell foam, Dow's SIS - structural insulating sheathing - and 2 staggered, taped 1" foiled rigid polyiso. Was hoping an alternative would prove less costly with the same if not better R- value.
Am getting prices for a few configurations, will post the numbers.
I continue to welcome any input/suggestions/comments,
Thanks again

A 2x6 studwall with open cell foam, R5 SIS and 2" of iso comes in at ~R30-R31 with framing factored in.

An alternate higher-performance stackup would be 2x6 cellulose (or open cell ) studwall with OSB sheathing, and  3" of reclaimed iso for the inner layer, with 1" foil faced on the exterior.  When using reclaimed goods a sheet of 3" is about the same (or less) per square foot as 1" foil-faced virgin-stock.  That stackup comes to about R35. Thicker foam adds a bit of expense to the window detailing and longer fasteners for the furring that retains the foam, but OSB sheathing is a lot cheaper than SIS- we're talking similar or lower money overall. 

If you want a true R40, go with 4" of roofing iso + 1" foil faced on the exterior, and a 2x4 cellulose or o.c. foam studwall.  (On a project I've been advising on locally they went with 3.5" reclaimed fiber-faced iso, 1" foil faced on the exterior, and cellulose cavity fill in a full-dimension 2x4 balloon framed structure- this is not an outrageous build.)

If you don't have local sources handling reclaimed foam from commercial roofing demolition,  Insulation Depot will deliver in truckload quantities (not so much for pickup-loads.)  It's catch-as-catch-can on inventory, but if you can store it in a dry place and plan ahead you can usually get the goods in time.


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25 Apr 2012 11:53 PM
You can reach high R values by using the 2x8 staggered stud Ray Core panels. Thermal bridging of the studs is eliminated but there is still bridging at top and bottom plates as well as window and door bucks. This can be minimized with a inch or two of EPS on the inside or outside. Are there any problems with this build up?
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26 Apr 2012 11:04 AM
Posted By Don Green on 25 Apr 2012 11:53 PM
You can reach high R values by using the 2x8 staggered stud Ray Core panels. Thermal bridging of the studs is eliminated but there is still bridging at top and bottom plates as well as window and door bucks. This can be minimized with a inch or two of EPS on the inside or outside. Are there any problems with this build up?

The R value is there, but the environmental impact high.  The lifecycle greenhouse gas impact of the blowing agents for 7.25" of closed cell polyurethane is far greater than the amounts it will offset in source emissions on energy savings for the building.  At 1", or even 2" that may not be true, but the diminishing energy returns of ever higher R-value renders closed cell polyurethane a strong net-negative at R40+

Iso & EPS manufacturers have been able use pentane rather than HFC245fa (or even worse ) for a  blowing agent, with more than an order of magnitude lower environmental impact.  There are more benign blowing agents for polyurethane in the wings, but they're not the current standard, and still nowhere near as benign as pentane.  The move toward HFC245fa was a big step in the right direction for the ozone layer impact, but high R using closed cell foam is a net negative from a greenhouse gas point of view.  Foam is not inherently green- far from it, but not all foams are created equal, and pentane-blown foams can go QUITE high in R before the impact is a net negative.  (This is partly why PassiveHouse structures rely on EPS rather than XPS for their high-R foundations.)

Cellulose is far lower impact than any foam product.  An iso or EPS clad stick-built with cellulose cavity fill, using small amounts of closed cell polyurethane for air sealing is a lot greener, and usually cheaper.  The case for using closed cell polyurethane for air sealing is pretty good, but not for high-R insulation.

Using reclaimed rigid foam from commercial building re-roofing & demolition is very low impact, independent of the blowing agents used in the original manufacture.  The environmental hit has already been taken, and reuse simply extends the benefit side of the cost^benefit balance for that hit.
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20 May 2012 01:46 PM
Posted By Dana1 on 19 Apr 2012 12:26 PM

The fact that Raycore has a foil facer on the interior side as well as on the exterior, the dew point of the interior air is irrelevant-  the applied sheathing has not one but two class-I vapor retarders between it and the interior air, as well as air-impermeable insulation. You could keep the interior a 60% RH all winter and not produce a measurable change in moisture on the exterior sheathing.

If you sheath it with OSB on the exterior you need to allow for a drying path to the exterior, since the facers prevent drying toward the interior.  An inch or two of XPS over the sheathing isn't a problems as long as you're not trapping moisture between the siding and the XPS. (Leaving at least 3/8" of vented rainscreen gap between the foam & siding would be a good idea.  Using 1x furring gives you twice that, and  better fastener retention for the siding.) 

Going thicker than 2"  with XPS would bring the permeance to the exterior to under 0.5 perms. But with fiberglass-faced iso you can go with any thickness, as long as you keep it to one layer.  Foil faced iso is out of the question, since it would trap the OSB between foil layers, a classic moisture trap.

The fact that Raycore panels are thermally bridged by 16" o.c. timber elements, the ~R7/inch of the polyurethane is largely wasted, with heat transfer dominated by those elements, and the website R-value references are somewhat deceptive. The "R26" of a 3.5" version works out to about an R12 average (which includes the sheathing, siding, and interior gypsum) at typical timber-fractions, less than half the stated R between the  wood elements   The R42 of the 5.5" version  works out to about R19 with the wood fraction factored in, if you include the top & bottom plates.  They do some thermal breaking on the 12" o.c. staggered-stud versions, which would be far preferable.

The website also talks up the thermal radiant-barrier value of the foil facers, but unless you allow at least 3/4" of air-space between the facer and the next element in the stackup that factor is negligible.

I'm not saying "don't use them", only cautioning to model them correctly, as performance will be roughly half what is implied by the numbers on their website.


Great discussion! I'm looking at these panels for the time saving properties as well. So would the method above (adding XPS outside the OSB) allow the Raycore panels to perform closer to their advertised R-values, plus adding extra R-value from the foam? On the 5.5 panel, what would you estimate the total R-Value with 2inches of XPS? Also, for spray foam-based panelized systems that come with OSB applied, would the above method also be applicable? Thanks!
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21 May 2012 11:29 AM
XPS uses the same high greenhouse potential blowing agents as closed cell polyurethane- use roofing iso with fiberglass facers (or reclaimed goods.)

With typical total framing fractions, a 5.5" panel with 16" o.c. studs would come in around R16, including siding, gypsum & air films. Adding 2" of XPS that would end up at R26. Adding 2" of polyiso would make that R28, still far short of the R40+ advertized R-value.

For the same wall thickness, a 3.5" panel (R11 w/framing) and 4" of iso sheathing (R25) would get you to ~R36 as whole-wall R, and would get the lifecycle greenhouse effect down to something close to break-even. EPS SIPs would have a lower lifecycle environmental impact though, since both EPS and iso are blown with much more benign pentane rather than the HFC245fa uses for closed cell polyurethane and XPS. (SIPs are inherently easier to air seal too.)

Using nailbase panels for insulating sheathing works just fine in this application.
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25 Jan 2013 01:23 PM
Thanks for your info. on Ray Core. Do you have any more info. on this subject? I have a client in N. Ca. who wants to use Ray Core for his house but I am concerned about all the potential problems you and GreenBuildingAdvisor.com list. Will you please email your System Comparison Cost / Performance chart to me, I can not read your one in the Ray Core article. What do you recommend? What do you think of the 8 1/2" EcoPanels? I live in a straw bale house I designed and built but I am not all that pleased with its performance. I think my weaknesses are the windows, skylights and the R-25 (approx.)rigid roof insulation.
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30 Jan 2013 01:20 PM
I saw your system comparison above but can not read it , will you please email a better copy to [email protected] Thanks
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30 Jan 2013 03:30 PM
Posted By john Cross on 30 Jan 2013 01:20 PM
I saw your system comparison above but can not read it , will you please email a better copy to [email protected] Thanks

I'm not sure Brian's comparison chart is particularly useful for your purposes, as the costs are highly local materials & labor market determined.  A pretty good discussion of the relative merits (including cost for performance) of differing approaches to high-R wall assemblies can be found on the Building Science Corp website (along with a bunch of other relevant info.) The performance construction, and comparitive cost discussions of the wall assemblies analyzed starts on page 28 (.pdf pagination) of this document

It's not as simple as a chart, but it's a far better discussion too. A list of assemblies analyzed and their whole-wall R values are in table 16, page 65.
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