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Quest for EPS

dfvellone | Posted in Green Products and Materials on

Finding extremely limited offering of eps rigid insulation in my region (upstate ny, north of Utica).
In my manufacturer search I found a product made by Cellofoam called Polyshield. They describe it as a sheathing product and it’s eps with polymeric facers on both sides added for strength.
Is anyone familiar with this product?

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  1. GBA Editor
    Martin Holladay | | #1

    If you Google Cellofoam Polyshield, you'll discover that Cellofoam North America makes a "Polyshield Family of Products" with a variety of thicknesses and R-values. Some are R-3.85 per inch, while others are R-4.17 per inch. What product are you interested in purchasing?

  2. Expert Member
    Dana Dorsett | | #2

    According to the short sheet spec, the standard product is poly-faced Type-I EPS, but Type-VIII and Type-II (preferred) can be special ordered. With facers the vapor permeance is specified to be under 1 perm.

    Searching your local craigslist, there is a reclaimer in Buffalo with some EPS is stock right now:

    And a reclaimer in Mayfield, NY selling 2" and 3" polyiso, as well as 2.5" reclaimed XPS:

    Most foam reclaimers have revolving stock, and may or may not have the thickness & type you are looking for at any given time, but it's worth contacting them. If the quantity is big enough, most will ship to your site at a reasonable cost, and still beat distributor retail pricing by half or more. The reclaimer in Mayfield is probably no more than 90 minutes drive from most locations in the Utica area

    Using reclaimed foam is both a lot cheaper and a lot greener than any virgin stock goods.

  3. dfvellone | | #3

    I believe polyshield sheathing/underlayment is what I need. It's r value is a little better than 4/inch.
    The only locally available product I can find is cellofoam's polyshield sheets (Lowes) but the sheathing product sounds more robust with polymeric facers on both sides.

  4. GBA Editor
    Martin Holladay | | #4

    Be careful: the reported R-value per inch of Cellofoam Polyshield Type 1 (the most common available type) is actually R-3.85 per inch (at a mean temperature of 75 degrees F -- the legal way to report R-value).

    The higher reported value (R-4.17 per inch) is at an unusually low temperature, and you can't use that number to compare R-values. According the the Federal R-value Rule, the standard way to report and compare R-values is at a mean temperature of 75 degrees F.


  5. dfvellone | | #5

    My understanding is that eps typically doesn't have the strength of xps or polyiso, but does this product with its facers compare in that regard? The type ii in particular? Any familiarity with it?

  6. dfvellone | | #6

    Would this be an appropriate product for my wall assembly:
    Plastered blueboard-membrain-full dimension 2x5 cavity with dense pack cellulose-3) 1" layers type ii polyshield?
    I'm in zone 6.

  7. GBA Editor
    Martin Holladay | | #7

    2x5 studs are unusual. Are these planed 2x6s that measure 5.5 inches?

    Do you plan to install OSB or plywood wall sheathing? Or will you be using EPS as your sheathing?

    In Zone 6, if you want to install rigid foam on the exterior side of a 2x6 wall, then the R-value of the rigid foam layer needs to be at least R-11.25. If you can find Type II Polyshield -- it's available by special order -- then three inches of Polyshield will have an R-value of R-12.5, so that will work.

  8. dfvellone | | #8

    The lumber is all locally sawn so I selected a full 5 inch cavity instead of the 3 1/2" 2×4's my engineer spec'd.
    No osb or other wall sheathing. The foam gets attached directly to the studs. I'm wondering if the facers on the eps present any kind of problem with the path of moisture. I am installing a 1" rain screen behind the siding.

  9. Expert Member
    Dana Dorsett | | #9

    Type-I EPS is pretty fragile stuff without the facers, but rugged enough when it has facers on both side. Unfaced Type-II is fine (it's the most commonly used material in insulated concrete forms.) Most roofing EPS is unfaced Type-II EPS, and walkable under membrane roofs. But the facers are usually true vapor barriers, with a vapor permeance less than 0.1 perms (even if they're only specifying it to be under 1.0 perms).

    It would be better if you use EPS without facers, in that stack up, to allow at least some drying toward the exterior. The reclaimers in my area sometimes get 1" EPS or 1" XPS in stock. At 1" thickness most Type-II EPS will be well north of 2 perms (but under 3) , and most vendors' XPS would be north of 1 perm (but under 2). It's easier to air seal foam with facers though, since foil tapes or housewrap tapes stick extremely well to clean plastic or foil facers. As long as you have the MemBrain on the interior it'll be fine, if not ideal.

    Foil faced polyiso would work just as well or better as poly faced Type-I EPS in that stackup, with higher shoulder season performance than the EPS. Polyiso is also somewhat better from a fire point of view, since it doesn't melt the way EPS/XPS does, and has a higher kindling temperature.

    Not mentioned in your stack up description is the structural sheathing (is there any sheathing, or is the wall stabilized with cut-in bracing?), and weather resistant barrier.

    Using the 40F mean temp specification for EPS is legitimate in this application, since during the heating season the mean temp of a skinny-inch of EPS on the exterior of R18-R19 cellulose will average 40F or lower at least most of the time. When it's 0F outside the mean temp will be WELL below 40F, and the performance even higher. In other applications the 75F mean temp performance number would be more relevant.

  10. Expert Member
    Dana Dorsett | | #10

    With no wood sheathing to damage the dew-point moisture concern is really for keeping the cellulose sufficiently dry. Cellulose is pretty tolerant (up to a point) and redistributes adsorb moisture without losing effectiveness, but if it takes on enough to develop frost crystals it can be an issue. Using Intello Plus instead of MemBrain would have less moisture diffusion, and unlike MemBrain, is tough enough to dense pack against without using a blowing mesh.

    If the exterior foam has facers, the rainscreen will not improve drying rates toward the exterior. Have you considered 1" rigid rock wool?

  11. dfvellone | | #11

    I am not using any structural sheathing, but am installing 1x4 let-in diagonal bracing.I have considered rock wool but it looked to be priced too high for our limited budget. I feel the same about polyiso- it's long term (or less than long by some reports) loss of r value, reduced r value as the temperature drops, and highest price of all considering these handicaps and it's higher price tag to begin with have me skeptical to use it.
    I can and will certainly switch to intello plus.
    You mentioned that as long as I have the MemBrain on the interior it'll be fine, if not ideal. What would be ideal?

  12. dfvellone | | #12

    If I use two 1" layers of polyiso that gets me above the required r value for my sheathing, but does foil faced polyiso allow for drying to the exterior? Seems that the foil face would have a low vapor permeability .

  13. Expert Member
    Dana Dorsett | | #13

    The foil facer allow zero drying, as previously stated.

    The labeled R-value of polyiso is higher than it's actual performance in your climate and stackup, but with only 5" of cellulose even at a derated performance 2" of polyiso would be more than enough, with MemBrain as the interior side vapor retarder:

    The center-cavity R of the cellulose is at most R19, and the derated value of the polyiso about R10, so you have at worst R10 / R29 or 34.4% of the total R on the exterior of the interior side foil facer.

    The IRC prescriptive of R11.25 on the outside of 2x6 presumes at least R20 in the cavities up to at least R23 (standard rock wool batts0, and a vapor permeance of ~5 give or take on the interior side. At R23 the total R would be R34.25, and the ratio would be R11.25 / R34.25= 32.8%. The R10 foam and R19 cellulose cenarario would have slightly less condensation issues than the IRC prescriptive.

    But 2.5" of Type-II EPS would be labeled R10, uprated to about R11.5 at outdoor temperatures that mattered. XPS eventually falls to the performance of EPS over time. That outfit in Mayfield with the stack of 2.5" recaimed XPS is probably going to be your best bet on semi-local price/performance, and it would still have some drying to the exterior, slow, but orders of magnitude more than through a foil facer:

  14. ranson | | #14

    I'm in the same boat, looking for a foam supplier in upstate NY. I found a company called Thermal Foams that has distributions centers all across the state. I wanted some EPS quotes for type II, XIV and XV, and they gave pretty reasonable sounding numbers for all of them.

    I tried posting this earlier, but I think linking to their website caused my post to be rejected as spam.


  15. Jon_Lawrence | | #15

    Universal Foam ( has distribution in NY. They quoted me type II and type IX for delivery in NJ with about a week lead time. They can also get me Neopor.

  16. peaceonearth | | #16


    Check out Amvic as an option ( The site has dealers in NY and VT, and a dealer locator on the website. This is EPS, and they have a variety of shapes, sizes and "types" (density and compressive strength). I am aware of 2" 4x8 sheets which I will likely be using. They have unfaced, not easy to come by, but also facings.

    Their specs identify R value at other than just the standard 75 degree testing temp, and at 0 degrees show the R value as 4.6 per 1", a good value for EPS (R value increases for EPS in colder weather, unlike polyiso, which does the opposite).

  17. dfvellone | | #17

    I appreciate all the great advice and assistance I've gotten here. I did purchase the reclaimed xps that Dana referred me to and look forward to it's delivery today, actually.

  18. MarkAno | | #18

    Martin/Dana/GBA Community:
    Is EPS Type I (1lb density) acceptable/strong enough for above basement slab use?

    2” of Type I (1 lb) EPS (10psi) for the following basement floor assembly:
    (Starting from the basement concrete slab going up):
    Concrete Slab
    2” EPS
    6 mil Poly
    2 layers of 1/2” Advantech OSB
    1 layer 3/4” Advantech OSB
    Luxury Vinyl Plank

    - No load bearing walls will be placed on assembly.
    - Typical basement furniture, bed, Home Theater chairs

    Heavier loads may include:
    - home gym equipment (treadmill, free weights on stand)
    - kitchen / wetbar with granite countertops
    - pool table

  19. Expert Member
    BILL WICHERS | | #19

    I’d say “yeah, it’s probably ok”. 10PSI works out to 1,440 pounds per square foot. That’s lots more than the live load, or even the live+dead load used to calculate normal floor loading. You might have a problem with point loads dimpling a bit (for example, the leg of a pool table will present a concentrated load of perhaps hundreds of pounds to about a square inch of floor area), but a thick plywood/OSB layer will help to spread that out. You could also make a disc of plywood or even framing lumber to help spread any concentrated loads out if needed.

    I’d still prefer type-II EPS though just to have some extra load carrying ability. Cost isn’t much different.


  20. Expert Member
    Dana Dorsett | | #20

    Type-I EPS is fine sandwiched between a slab and a subfloor, as long as the seams of the subfloor are at least a foot away from those of he foam (except where they cross perpendicularly.)

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