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About 6 months ago I reported on a Canadian 2 year research program on expanded polystyrene (EPS) rigid foam board insulation (RFBI) below ground on a concrete foundation.
The full report has been published in the October 1999 issue of the Journal of Thermal Envelope & Building Science and is entitled: “In situ Performance of Expanded Molded Polystyrene in the Exterior Basement Insulations Systems (EIBS).”
Skeptics and believers with questions contact Mike Swinton at NRC Canada, (613)993-9708. I do not know his e-mail address. GeneL
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I have found Mike Swinton's e-mail address: [email protected]
Patrick hasdone a synopsis of this report and you can read it on the first section of BT..the one you do not have to click on. GeneL
*Gene, I've been picking up just enough information about foam insulation from the NRC site to be dangerous (mis-informed).How well does EPS stand up to the compression force of ground movement? Is this a factor?
*Scott. Thermal and mechanical properties of the ESP were meas ured after the exposure. quoting, " In general these results ...confirmed that there was no significant change in any of the measured properties-thermal resistance, compressive strength, and water vapor permeability." Again " The insulation specimens were removed after 30 months of exposure in the soil.Moisture content as well as thermal and mechanical properies of the materials were evaluated in the laboratory and compared to initial properties. It was concluded that the specimens did not show signs of deterioration in thermal or mechanical performance."I hope this answers your question, Scott. I posted this message on BT 3 times, and in one of them Patrick made several direct quotes you mmight find of interest. GeneL.
*Thanks Gene. I caught Patrick's summary back when you first posted. EPS is considerably cheaper than RFBI, so the decision on what to use is getting easier.Many of the NRC papers I skimmed kept referring to the loss of R value of foam products over time. I haven't found anything that put the loss into a perspective I could understand. Do you have any info?
*Scott. There has been a lot of research into the loss of R-value over time on PIR, PUR, extruded and molded rigid foams. DOW Chemical has done a lot of research on this subject. Some of these papers were published in ASHRAE Transactions and in ASTM's STP (Special Technical Publications). Unfortunately some of these studies--particularly on EPS- are biased, as the NRC ( and other research) testings shows. Sweden has long used ESP below ground, but warns that higher compressive strength foam baord is necessary under heavy loads.I cited the NRC research because it is current. But others, years ago, did similar testing and found that the arguments against using EPS below ground were unfounded.I'll do some searching in my library. In the meantime contact Mike Swinton at [email protected]. I'm certain he can help you. GeneL.
*......we avoided EPS with solar because we were building 10,000 gal water tanks on them and needed the rated compressive strength of say Styro-SM,now a lot of the studies show that they can build almost any distributed load on EPS, and the studies that GeneL refers to above seem to indicate no measurable R-value loss even when submerged.. which is also contrary to what we were told then...looks like I might be using EPS under my slabs... or did I read it wrong?
*Mike. You read correctly. However, as I noted, the Swedes caution that EPS has limited compressive strength--I can't quote the numbers off-hand. For heavier loads one must use XPS, and for even heavier loads use cellular glass insulation such as Foamglass. See Subslab Insulation page 78-79 in my book Complete Building Construction, 4th Edition.
*Scott, et al. The American Society of Testing and Materials (ASTM) publication, Thermal Transmission Measurements of Insulation,STP 660., (Special Technical Publication 660) contains the paper, "Laboratory and Field Investigations of Moisture Absorption and Its Effects on Thermal Performance of Various Insulations." This is the well known--among researchers--Dechow/Epstein( DOW employees)report. This and other papers were the basis of my banning(when I was Code Enforcement Officer)EPS and unfaced PIR below ground. Indeed, I stopped builders from uing foil faced PIR RFBI below ground. Typical backfilling practices guarantee the destruction of the crucial foil facing on these RFBIs. The interesting thing is that the Dechow/Epstein findings re EPS are at odds with several research studies, the most recent of which is the Canadian National Research Council (NRC) 30 month study of EPS.I'll continue researching for the other papers, and will post their names here. GeneL
*I feel compelled to shed some light on the misperceptions associated with EPS. I'm in the last two weeks of employment with an EPS manufacturer, and after ten years, I feel qualified to respond.EPS can be purchased with a compressive strength suitable for almost any application. Manufacturers produce a wide range of densities from .5pcf (pounds per cubic foot) up to and beyond 3.0pcf. A typical 1.0pcf conforms to ASTM C-578 and has a compressive strength of at least 10PSI. However 2.0 PCF will deliver a strength of at least 40PSI. That is significantly higher then Dow's SM board. The majority of EPS plants can supply a 3.0 pcf foam which will deliver 100 psi .The use of EPS below grade isn't just acceptable, it's without question the best bang for the buck.If the price and the strength doesn't convince you, how about them termites to help you decide. Thats right, for those builders in termite or carpenter ant territory, EPS is a MUST. Recent SBCCI revisions prevent the use of any foam related products below-grade. The one exception is EPS with Borate infused into the foam. It's refered to as "Perform Guard" and is available from any AFM plant.The use of EPS below-grade is also rapidly expanding in the area of civil engineering. Geofoam is the term used when EPS is used for areas of ground stabilization and light-weight fill. I've supplied Whole blocks of EPS (3'x4'x16')to build every type of structure on top of you can think of including major highways. I don't want to ramble on,but would be happy to discuss, at length, any specifics regarding EPS. My new job will specialize in EPS consulting from manufacturing start-ups to structual insulated panelsregards Al
*..tell me more Al.. Perform Guard is just what I'm looking for... what about flame spread?how about some web sites?...come on over to the tavern and I'll buy ya a "GansettMike
*Mike,Funny thing, there is an AFM plant right next to you in Rhode Island. I bought ICF's from them because of the borate treatment. I have more info; I'll find it.Jerry
*Mike,Here's a link for R-Control Building Systems which used to be called AFM Foam Corp. http://www.afmcorp-epsfoam.com Click around and you will find info about their products which are produced locally (to you) at:BRANCH RIVER FOAM PLASTICS, INC.15 Thurber Blvd.Smithfield, RI 02917PH: 401/232-0270Toll Free: 800/336-3626http://www.branchriver.comJerry
*...boy Jerry, is my face red... smallest state in the union and i didn't know that...my only excuse is that I have religously avoided EPS and Stress skin like the plague..so all this new info on EPS has been very helpful to me...thanks again all..
*Mike, Who has time to think about EPS when you have all those quahogs to dig?Priorities, man, priorities!
*....shhhhh...Mongo ... don't let 'em in on itp.s. the oysters are back ,too
*al cobb. Please help me out. It is my understanding that there are two measurements of the compressive strength of EPS. One of them tests the ability of EPS to resist creep under load. The other I can't qiite state. but it is not the same as compressive strength..I've quoted the 1995 testing of EPS--among other foams--because it is the latest research. But 10 or more years ago there was testing of EPS below ground done by some lab other than DOW Chemical. One of the tests was conducted in Michigan or by the University of Michigan. Can you help on this? For those of you who have access to ASTM publications, see "Thermal Performance of Various Insulations in Below-Earth Grade Perimeter Application,"In ASTM STP 789, Thermal Insulation, Materials, And Systems For Energy conservation In The '80s. GeneL.
*Mike,I see you got the web site for AM ( -Control Building Systems ) They can provide you with numerous locations as well as more technical data.Your question about flame spread can get confusing, but I'll plug away here for awhile. Timber is the substance used to treat the foam. It is a borate also commonly used in pool filters but referred to as diatamatious earth. The chemical name is disodium octaborate tetrahydrate. The largest user of this product is the fiberglass insulation industry. You guessed it, they use it for improving both flame spread and smoke development figures. Likewise Perform Guard foam enjoys a marked improvement in the same figures when testing EPS. Boron is a natural fire suppressant. This is why it is also widly used in the baby clothes industry as well as commercial rugs and draperies.So what is the flame spread? Doesn't matter. Even with a boost from the introduction of Borate, EPS is still considered a combustable by every code-body.Manufacturers already use what's referred to as a modified resin to get flame and smoke numbers down to a level that allows it's use as a building product. Compared to a foam plastic cup which will burn completly, Modified foam will self extinguish after the source of ignition is removed.The short answer is : Borates help lower both numbers, but not enough to make much of a difference.More on EPS strengths (Flexural vs. Compressive) and the infamous Dow(We've got more money so we'll do the test our way) Styrofoam report to followI hope this is helping.AL Cobb
*... Al... keep 'em comming..as you can guess , i was hoping that the flame spread would be low enough to allow unprotected installation in areas like attics , kneewalls, and crawl space walls...i read that you're saying that it still has to covered with 1/2 " sheetrock or equal???thanks, Mike
*Gentlemen. In 1989 The Society for the Plastics Industry (SPI) sponsored a 3 year research program to study the suitability of using EPS below ground. Yhe testing was conducted by Twin City Testing Laboratory in St. Paul, Minnesota. Technicians installed 4'x 8'sheest against a below ground foundation. Two types of ESP wer used: 1 pcf and 1.5 pcf.Each year one of each type of ESP was dug up and each material was measured for water absorption, density, and R-value. Samples were taken from the top, middle and bottom of each panel.The 3 year test showed that freeze thawing cycle had little affect on the boards, and that the boards'R-value dropped less than 10%.About the same time the Minnesotsa Department of Public Service conducted a 59 house field study opf buried ESP. This study found that the ESP retained less than 1% moisture and R-value dropped less than 4@. GeneL. Each year the pabels were gug up
*Gene, I believe what your referring to is compressive strength and creep as a function of compressive loading. The test for compressive resistance(or strength) is an instantaneous test which measures PSI exerted upon the material until 10% deformation occurs. Once the 10% threshold is reached, the test is over.The extended version of this test measures "creep". The same loading that would deform a sample piece by only 10% may crush by 50% or more if left for a long period of time. The common tool used by engineers and spec writespeds a stress vs. strains.aph. A high stress to strain ratio indicates poor resistance to creep.EPS used aESPeofoam (below grade) usually adheres to a spec of 1%spedormation which allows 7 psi loading as opposed to the 10 psi @ 10%(for 1.0 pcf EPS). ThisESPcrease makes creep virtually insignificant. Hope this helps , AL
*The building codes in this area doesnt allow any type of EPS below grade without a treatment and inspection gap. So why bother if you cant complete the whole envelope. JMHO
*Jerry, AL. Gene.. et all.. got a quote today from Branch River Foam... if i switch from 1" ISO to 1" EPS i go from R-7 to R-4... but i also go from $14 a sheet to $4 a sheet.. so , since i'm mostly looking for a thermal break, the r-4 will propbably be my choice...in the crawl space they can give me Performguard 3" (R-14) with cement board laminated to it so i don't have to worry about flame spread and i can have the foam in ground contact to insulate the concrete walls... for $51 a sheet.... sounds expensive.. but i only need 8 sheets . and i install it and i'm done.. no vermin, no wet sheet rock, ..hmmmm.
*Gentlemen. for those who would like a copy of the Canadian NRC study call Thomas Greeley's office at BASF at 800-526-1072 Extension 3908. Also ask for copy of Minnesota study. You'll probably not get to speak to him so ask his secretary for the copies. GeneL
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About 6 months ago I reported on a Canadian 2 year research program on expanded polystyrene (EPS) rigid foam board insulation (RFBI) below ground on a concrete foundation.
The full report has been published in the October 1999 issue of the Journal of Thermal Envelope & Building Science and is entitled: "In situ Performance of Expanded Molded Polystyrene in the Exterior Basement Insulations Systems (EIBS)."
Skeptics and believers with questions contact Mike Swinton at NRC Canada, (613)993-9708. I do not know his e-mail address. GeneL