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re: materials economy
12 feb 1997
kevin willmorth wrote:
>...low lying roof lines are structurally more materials intense than
>a steeper roof line.
i suppose there's a tradeoff. low-lying roofs in snowy places need to be
stronger, but the shape has less surface area, so they can use less materials.
>unfortunately we compound steep roof pitches with attempts to duplicate
>our old world clay tile or wood shake roof systems. if we coupled the economy
>of deeper trusses with the use of recycled rubber products, and accept the
>new look, we could gain on two levels.
"deeper trusses with recycled rubber products" sounds like a flat roof with
plywood trusses covered with epdm rubber to me. is that the sort of thing
you have in mind? can worn-out tires be turned into epdm rubber? i asked a
roofing supplier why people don't use more epdm rubber for house roofs, and
they said one thing is, it comes in large rolls, with large leftover pieces,
vs shingles...
>next, we are still using driven fasteners. nails are seriously obsolete
>in the face of conserving materials. bolted connections, glued and
>screwed joints are much more robust and can contribute to a reduction on
>the amount of materials used.
seems to me that using screws makes the structure more recyclable too.
>dab a little concrete into the formula...
monolithic domes come to mind, with 2" of reinforced concrete (overkill) and
3" of polyurethane foam on the outside, and a vinyl "airform" or some sort of
ceramic or mastic paint over that. inflate the airform, spray on foam from
the inside, apply little plates with wires sticking out while the foam is
tacky, wire on reinforcing rod, spray on concrete costing less than 20 cents
per board foot from the inside, wait 2 or 3 days, take a deep breath, thinking
they have been doing this for over 20 years now, then turn off the blower.
but it would be nice if there were less concrete, and it had some polystyrene
beads in it, and so on. concrete seems expensive as thermal mass, vs water,
especially since water has about 3 times the heat capacity by volume. how
can we do all this starting with something like a bolt-together pacific dome,
a lightweight thing made with steel tubing and canvas...
>another factor is our use of materials to gain a traditional finished
>appearance and flase economy. interior walls that are 4" thick, that do
>not carry a load, are a certain waste of material.
a friend pointed out the only such (small) wall in his home-built house.
most of his other walls had only one side, being load-bearing bookcases, etc.
>bedrooms... are too large to warrant the use they really get (they are
>empty, heated and air conditioned boxes sitting empty for 16 to 18 hours
>out of 24)...
i guess many people don't know or care about zoning and setback thermostats...
>add big windows to get a little daylight into those night time
>sleeping spaces and you've got a very strange situation.
if the big windows are part of a dramatic and inexpensive 2-story low-thermal-
mass lean-to sunspace adjoining the bedroom, they can easily heat the house...
>big expanses of glass in a tight community (affording us a great view of the
>neighbors big expanses of glass), is just stupid, they eat energy to
>manufacture and suck energy from the interior itself (even the best windows
>made today are low in r value compared to good insulated wall construction).
it would be nice if someone started making very clear mylar in big sheets
again, or if tastes change to accept the look and privacy of partly cloudy
greenhouse polyethylene film, which has a 4 year guarantee and comes in rolls
up to 40 feet wide and 150 feet long, costing about 5 cents per square foot.
this film lasts a lot longer when covered in summertime with green shadecloth
costing about 20 cents per square foot.
>we don't need just new materials, we need a new approach altogether!
nice posting, kevin :-)
nick
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