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Dense pack perlite (sawdust?) in holl…

| Posted in Energy, Heating & Insulation on March 13, 2002 05:22am

*
I’m getting ready to build a house in Montenegro Yugoslavia. The weather is a wet Pacific Northwest/New England weather. We have around 80 inches of rain (some of it horizontal because of wind). In the winter the weather hovers around freezing with snow turning into slush and lots of freeze-thaw cycles. Our summers are moderate without humidity (except when it’s raining).

Most people around here build with concrete block. Labor is MUCH cheaper than in the U.S.

I’ve appreciated recommendations on windows, now I would appreciate your discussion on a type of insulation I have not seen discussed much:

I was thinking of building a double wall out of concrete block or stone (possibly autoclaved aerated concrete blocks) and filling the cavity with perlite. The cavity will be around 10 inches–I plan on having the outside wall self supporting (no ties between the two walls) and being part of a wrap around porch which will help with wind blown rain.

Any recommendations?

There is a mill nearby where I could get all the sawdust I want. Any ideas about using sawdust? I’m afraid it would decompose or mold over time.

Finally there is the ubiquitous issue of the vapor barrier–what are your thoughts?

I had thought of laying stone walls up against both sides of thick rigid foam, but common wisdom around here says a house should “breathe.” I have also had rodents and birds chew up polystyrene so I am hesitant to use it.

Thanks

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Replies

  1. LFred | Mar 08, 2002 06:52pm | #1

    *
    Block walls do not have to breath.

    1. Art_B. | Mar 08, 2002 09:34pm | #2

      *An old fish cannery freezer plant (late 1800's construction)in Seattle had sawdust insulation between clay block walls, worked well as insulation. Recall the b;uilding caught fire in the 1980's and it took 4 weeks for the sawdust to finally stop smouldering. Possilbly treat with Sodium Silicate first for your application??

      1. Stanisa_Surbatovich | Mar 08, 2002 10:06pm | #3

        *A plus for perlite. Though I would think the masonary would help the sawdust not to ignite--but so should have the clay block walls in the cannery freezer plant.Houses here are generally not insured.

        1. Kerr | Mar 10, 2002 12:08am | #4

          *Is the (former?) capitol of Montenegro (Crna Gora) still called "Titograd", or has it been changed since all the troubles in the last twenty years? (my atlas dates from 1990...)I am very sorry when I think about all the bad that has occured in your part of the world since the fall of the Soviet Union. Reading your post reminds me that my father was at the Olympics in Sarajevo and brought me back a cassette tape of local rock music by a band called "Animatori" and when the war(s) broke out over there I often wondered if any of the members of that group ever survived. So very sad.I am made happy to hear that you are building a house, because that sounds like seeing flowers after a forest fire. Good luck to you and best wishes!

          1. Dave_Richeson | Mar 10, 2002 08:15am | #5

            *I worked on several super stores back in the early and mid eighties that had "zonelite" poured in the block walls for insulations. As far as I could tell it is the same as perlite. I don't know if it is still used, but I believe it was rather ineffective in a single block wall construction. Something about the block web and ends providing a big thermal bridge vs. the R value of the zonelite. Now your idea of two walls with a sepperate insulated cavity sounds like it would be much better.Anyone know the r value for zonelit or perlite?

          2. Stanisa_Surbatovich | Mar 11, 2002 10:32am | #6

            *The working capitol is now called Podgorica which was its name before Tito's time.Now that Montenegro is moving towards once again being an independent country (it had been independent until 1918 when it was forcibly anexed by Serbia/Yugoslavia), the historic capitol Cetinje is also being used.I don't know about the band.Since Montenegro is a small state and courting the West it has a a good potential for reform and recovery.Thanks for your interest.Stan

          3. Stanisa_Surbatovich | Mar 11, 2002 10:35am | #7

            *Architectural Graphic Standards lists the folling R values:For perlite:2-4.1 (lb per cu ft) R per inch = 3.54.1-7.4 = 37.4-11 = 2.6For wood fiber AGS lists R = 3.3 (I have seen other references indicating the R value for sawdust between 2 and 3.3).The perlite I would be using falls into the R = 3 range.Stan

          4. splintergroupie_ | Mar 12, 2002 04:00am | #8

            *"Zonolite" is a trade name for vermiculite, expanded mica, the stuff that carried asbestos fibers and contaminated workers in the Grace mine in Libby, Montana, but seems to be pretty non-lethal elsewhere in the world. Perlite is a different thing, expanded volcanic material, basically glass, inert. Still, you don't want to breathe glass. Wear a mask.

          5. Dave_Richeson | Mar 13, 2002 04:37am | #9

            *sg,Thanks, I did not know that. Do you know what the lower exposure level was/is for zoneolite? I don't think I was ever exposed at the level mine worker were, but I sure breathed enough of the stuff to be concerned. Dust mask and respiratores weren't very common on commercial job sites twenty-five years ago.Dave

          6. splintergroupie_ | Mar 13, 2002 05:22am | #10

            *Dave, not all vermiculite carries asbestos. The mine near Libby, MT was from a different earth age that what is found elsewhere--maybe this is why it was esp bad. Anyway, dust itself is harmful, but asbetos fibers in addition to dust particles compound the trouble.Google for vermiculite+cancer and you get all the info you might not want. One of the things you need to keep in mind is that dust alone, even without asbestos, can be harmful. My mom had a good portion of her palate removed to deal with a relatively rare cancer that was found with unusually high frequency in factory workers who breathed very small dust particles that lodged in their sinus cavities.

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