Foundation Insulation & HCFCs

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Author Message Anonymous   Posted on Wednesday, September 10, 2008 - 05:47 pm:    Not sure if this is supposed to be in this or sustainable forum, but...it's my understanding that extruded polystyrene is typically spec'd for perimeter/foundation insulation. But extruded is blown with HCFCs. Does anyone know if molded polystyrene (I think can be blown without HCFCs) can be used instead? One mfr's tech data says extruded is better for reactivity with soil, but same mfr does not say same about their molded type. Anyone have any thoughts? Mark Gilligan SE, CSI Senior Member Username: mark_gilligan Post Number: 87 Registered: 10-2007 Posted on Thursday, September 11, 2008 - 12:27 am:    I suggest you talk to one of the manufacturers of molded polystyrene. My understanding it that they have very effective systems to capture any polutants thus essentially making this a non issue. Anonymous   Posted on Thursday, September 11, 2008 - 07:43 am:    My understanding is that if you place 2 inches of expanded/molded polystyrene at perimeters and foundations, in about 5 years you will have a two inch space at your perimeters and foundations. Phil Kabza Senior Member Username: phil_kabza Post Number: 332 Registered: 12-2002 Posted on Thursday, September 11, 2008 - 09:42 pm:    The data on most molded polystyrene shows a much higher retention of moisture over time than the data for extruded polystyrene. That's a serious drawback. Both types of plastic foam are considered munchies by carpenter ants and termites, by the way. Just in case you didn't have anything to worry about today. Anonymous   Posted on Friday, September 12, 2008 - 12:22 pm:    Here's a link to an ASTM publication on using EPS in below grade conditions: http://astm.info/DIGITAL_LIBRARY/STP/PAGES/STP11025S.htm Anonymous   Posted on Friday, September 12, 2008 - 12:19 pm:    Phil, Can you please provide a link or citation to the data that you reference in the post? This is contrary to the only third party test I have seen, published by Cutter some years ago, that shows molded and extruded virtually in a dead heat for moisture accumulation in contact with earth in below grade walls. It was a Canadian study. There are other studies available that corroborate the findings in the Cutter article. Also, the ASTM standard that governs the quality of EPS limits the amount of allowable absorbtion. I have never had any moisture absorption issues in specifying EPS and have never seen any evidence that there is any problem in doing so. Ron Beard CCS Senior Member Username: rm_beard_ccs Post Number: 281 Registered: 10-2002 Posted on Friday, September 12, 2008 - 03:42 pm:    I have used EPS foam in many below grade applications for both structural, thermal, and structural and thermal uses without adverse effects. When using EPS in structural applications, density should be carefully considered (ie, 30-psi for typical roofing applications or below grade thermal applications; 40- to 60-psi for use under point loading like paver pedestals; 100-psi under heavy loading like under large tree planters in roof/deck applications or roadways). Here is a link that provides EPS in structural highway, among many other uses. This website has many other links for investigation. Oblviously there are many other companies out there. http://www.geofoam.com/ PS: My original understanding of the term "molded" foams was those foams used in coffee cups and packaging. Mark Gilligan SE, CSI Senior Member Username: mark_gilligan Post Number: 88 Registered: 10-2007 Posted on Saturday, September 13, 2008 - 01:41 am:    When using polystyrene foam in structural applications the issue is typically not so much strength but rather stiffness. A foam with a compressive stress of 25 psi can support 3,600 psf which will likely support any tree planter. The problem is that this strength is defined at 10% distortion. This means that 12 inches of 25 psi foam would compress 1.2" at full load. The good news is that this strain is not linear and at lower stresses the stiffness of the foam is higher thus resulting in a generally level of distortion. I like to keep the expected loads at less than half of the rated compressive strength. I would recommend either a layer of soil or a hard surface such as a concrete slab over the foam to spread out the point loads and prevent localized crushing. Note the link Ron provided points to ASTM D6817 while the foam typically used for buildings is ASTM C578. My discussion above was in the context of C578.. Note that the foam in ASTM D6817 has significantly lower compressive stresses which are measured at 1% deformation. My guess is that the underlying foams are similar structurally. Do not use foam where gasoline exposure is likely since it will disolve. Lisa Berryman (Unregistered Guest) Unregistered guest Posted on Friday, September 19, 2008 - 05:08 pm:    In my area XPS is always spec'd for perimeter/foundation insulation. EPS Expanded Polystyrene is HCFC free, conforms to both ASTM C578 and D6817, is mold free, can be treated with pesticides, and has recently tested very well against water absorption. Water absorption results can be viewed at epsmolders.org technical bulletins are linked right from the home page. EPS Type 1X is the best suited for this application. It does have a lower R value per inch than XPS but can easily be ordered in 2.5" thickness to attain an R value of 10.3 or 2.38" to meet the R value of 10. You may want to look into ASTM C1512 which assess the effect of freeze-thaw cycling on thermal performance and also moisture absorption, EPS holds its own here also. For those of us unfortunate enough to live in northern parts of the country this a concern. The downside of EPS is it should not be used when it will be exposed to hydrocarbons or petroleum based solvents of any type. That would be the only reason you should ever expect to have the foam dissolve John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 964 Registered: 03-2002 Posted on Tuesday, September 23, 2008 - 08:55 am:    Lisa, in what area are you located? (Unregistered Guest) Unregistered guest Posted on Thursday, September 25, 2008 - 10:03 pm:    I am located in southwest Michigan John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 968 Registered: 03-2002 Posted on Friday, September 26, 2008 - 08:37 am:    In New England, I never see expanded used in either foundation or roofing applications (commercially). Lisa, in your post, are you suggesting that expanded could be appropriate for foundations? Is it less costly "per R"? Dale Hurttgam, NCARB, AIA,LEED AP, CSI Senior Member Username: dwhurttgam Post Number: 37 Registered: 10-2005 Posted on Monday, September 29, 2008 - 10:43 am:    I am in the southeast Michigan area, and I believe that extruded polystyrene insulation board is used almost exclusively in this area for perimeter/foundation insulation. Lisa Berryman (Unregistered Guest) Unregistered guest Posted on Wednesday, October 01, 2008 - 12:04 am:    It sounds like Michigan and New England follow the same spec guidelines. I believe it is due in many cases to lack of available test data on moisture absorption in the past and a great marketing job by O/C and other extruded manufacturers. The cost per R value is typically less for EPS than XPS. Some of that may be determined based on EPS manufacturers being in your area. In my area I would estimate between 10-20% savings. A 2# density EPS would provide a compressive resistance of 25 psi @ 10% deformation and an R value of 4.2 per inch@ 40 degrees. Local cost for a 2.5" x 48 x 96 sheet is about $18.40. A 3# density EPS would provide a compressive resistance of 40psi @ 10% deformation and an R value of 4.6 per inch@ 40 degrees. Local cost for a 2.25 x 48 x 96 sheet would be about $23.04. The upside is EPS does not contain HCFC's, retains its thermal value see epsmolders.org for specifics, it has the ability to be treated with pesticides, and can be cut to any thickness, width or length prior to job site delivery. EPS blocks are molded (typically in 32 x 48 x 96, 120, up to 288) and wire cut to job orders. The downside is EPS cannot currently hit the 60 psi mark and our marketing budgets are limited. Regarding roofing, within Michigan we ship out a minimum of 100 truckloads per year for roofing applications only. Frequently it is sandwiched between 2 layers of ISO to add an inexpensive taper but not always. Much of it goes into flute filler for metal decks and just plain flat sheets in place of ISO. Sometimes it is spec'd that way, sometimes it's an addendum due to a commercial project going over budget and looking to hit an R value at a lower cost. Anonymous   Posted on Wednesday, October 01, 2008 - 10:38 am:    For those who specify extruded for perim/fdn applications, how (if at all) do you reconcile the HCFCs on a "sustainable" (i.e., LEED) project? Orig Anon Ronald L. Geren, AIA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 685 Registered: 03-2003 Posted on Wednesday, October 01, 2008 - 11:21 am:    LEED doesn't concern itself with HCFCs--or even CFCs--in insulating materials (at least in LEED-NC 2.2), unless you consider it for an "Innovation in Design" credit. Lisa Berryman (Unregistered Guest) Unregistered guest Posted on Wednesday, October 01, 2008 - 02:36 pm:    EPS can be provided in a 25% Recycle content - manufacturers actually refer to it as construction grade. How would this calculate towards LEEDS credit? John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 970 Registered: 03-2002 Posted on Wednesday, October 01, 2008 - 03:28 pm:    Lisa, It would be part of the calculation for recycled content under credits MR 4.1 and 4.2. One could refer to it as "contributing to LEED credits MR 4.1/1.2," but never imply that it can get such a credit by itself--no product can do that. (By the way, LEED is singular, never plural, unless you are referring to the city in England.) Your posts are interesting, and I will be looking into the use of EPS in future projects.