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EPS BELOW GRADE IN WET SOILS

| Posted in General Discussion on September 14, 1999 10:53am

*
Somw rime ago I suggested using expanded polystyrene EPS on interior and exterior of foundations.After all the Swedes are using it below ground. Some claimed that because Sweden is “dry” EPS belowgrade was OK.

EPS has gotten an undeserved black eye based on DOW’s published test results. The tests claimed that EPS would deteriorate and lose its R-value when subjected to freeze-thaw cycling and water.

Back in 1995 Canadian National Rsearch Council(NRC) researchers installed eight types of RFBI–including EPS Type 1 and 2 as described in CAN/ULC-S701-97-on basement walls at test Hut 1 in Ottawa, Canada.

Sensors were placed and backfilling was done carefully. Researchers monitored the RFBI for more than two years, recording soil moisture content, weather conditions, soil temperature, and thermal performance of the RFBI. Two heating seasons later the RFBI was removed and sent to a lab and compared to the RFBI’s condition befor the burial.

According to the head researcher they found no deterioraion in the ESP RFBI’s mechancial properties or loss of R-value.

By the bye. Canada’s National Building Code was recently changed to allow the use of low density EPS(CAN/UL-C-S701-97 Type 1) below grade in residential construction. With the exception of Ontario and Alberta, all provinces and territories have changed their codes. Ottawa and Alberta are expected to approve the change during the 20001 code cucle. GeneL.

Reply

Replies

  1. Patrick_M. | Sep 11, 1999 09:20am | #1

    *
    Gene

    Why EPS (R3/" ?) and not XPS (R5/"). XPS is also "waterproof".

    -pm

    1. Gabe_Martel | Sep 11, 1999 06:29pm | #2

      *Hi Gene,You forgot to mention one important feature of the testing after removal. The samples were dried and then compared.When wet, the R was not as good.GabePS Why do we have to wait 18,000 years before we change the code in Ontario?

      1. Gene_Leger_ | Sep 11, 1999 08:30pm | #3

        *Patrick. Included in the eight types of RFBI used were fiberglass board, mineral fiber, sprayed PUR and of course Type 1 and Type II ESP. I don't know if XPS was in the group. I hope to be talking to Mike Swinton on Monday. By the bye. Researchers made no attempt to keep surface water away from the RFBI. The ground was sloped down and toward the foundation.GeneL.GABE. Thanks for calling that to my attention. It's obvious that I don't have all the information. As noted, I expect to talk to Mike Swinton at NRC on Monday.Re the 18,000 years. It is my understanding that neither Ottawa nor Alberta can simply change the code. They require provincial legislative action to make the change.GeneL.

        1. Gabe_Martel | Sep 12, 1999 03:43am | #4

          *HI Gene,I don't think that the province will wait until the year 20,001 before considering any changes, maybe the year 2001 but not much longer, don't you agree?Couldn't resist that one Gene, sorry.Gabe

          1. tedd | Sep 14, 1999 07:10am | #5

            *Its real important to make the distinction between Type I and Type II Expanded Poly-Styrene foam. Type II is superior in all performance characteristics (according to the test data I have read). I don't know the Canadian Code numerical designations but I suspect that the approved underground EPS is Type II (not Type I). Please clarify this. The US doesn't seem to recognize Type I verses Type II although I haven't seen their Code books. Type II has a slightly higher R value than Type I. Type II is steam blown rather than air blown so this may explain its tougher and hardier behavior. I have had a chance to seen Type I come out of the ground after years of freeze-thaw and compressive,mechanical action and it it isn't a pretty sight. I think one has to take into account that EPS is not so well defended against various chemical-caused deterioraton (adhesives, gassing off, vehicle exhausts, agri-chemicals, caulks; etc). What are the recommended in-ground (foundation realted) methods for attaching EPS to concrete and also bonding one sheet to the next ?

          2. andrew_d | Sep 14, 1999 10:53am | #6

            *... and you mention interior EPS?

  2. Gene_Leger_ | Sep 14, 1999 10:53am | #7

    *
    Somw rime ago I suggested using expanded polystyrene EPS on interior and exterior of foundations.After all the Swedes are using it below ground. Some claimed that because Sweden is "dry" EPS belowgrade was OK.

    EPS has gotten an undeserved black eye based on DOW's published test results. The tests claimed that EPS would deteriorate and lose its R-value when subjected to freeze-thaw cycling and water.

    Back in 1995 Canadian National Rsearch Council(NRC) researchers installed eight types of RFBI--including EPS Type 1 and 2 as described in CAN/ULC-S701-97-on basement walls at test Hut 1 in Ottawa, Canada.

    Sensors were placed and backfilling was done carefully. Researchers monitored the RFBI for more than two years, recording soil moisture content, weather conditions, soil temperature, and thermal performance of the RFBI. Two heating seasons later the RFBI was removed and sent to a lab and compared to the RFBI's condition befor the burial.

    According to the head researcher they found no deterioraion in the ESP RFBI's mechancial properties or loss of R-value.

    By the bye. Canada's National Building Code was recently changed to allow the use of low density EPS(CAN/UL-C-S701-97 Type 1) below grade in residential construction. With the exception of Ontario and Alberta, all provinces and territories have changed their codes. Ottawa and Alberta are expected to approve the change during the 20001 code cucle. GeneL.

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