[GSBN] FW: Strawbale Drip Testing Report

Tue Apr 7 18:57:52 UTC 2009

Yeah, interesting.  I'd be most interested in knowing how the water migrated
within the bale horizontally...
John

On Tue, Apr 7, 2009 at 5:39 AM, Mark Piepkorn <mark at buildinggreen.com>wrote:

> Though the methodology doesn't replicate how things would happen in the
> real world with a wall assembly, I think the findings are interesting and
> that TLS should run it - if for no other reason than to encourage other
> people to think about things, and to do their own experimenting, and to
> report back about it. This opinion assumes that it wouldn't bump other more
> immediately pertinent info.
>
> I also think this is an excellent use of GSBN-as-TLS-advisors, and wouldn't
> mind seeing you use GSBN this way more often.
>
> I'd like a copy of the pdf, please. If you choose not to run it as a TLS
> story, I'd be interested in doing something with it at some point - with the
> author's permission.
>
>
> Mark
>
>
>
> At 07:08 AM 4/7/2009, you wrote:
>
>> Hello,
>>
>> I received the following report from Tim Rudolph from California asking if
>> I
>> was interested in sharing this report in a future TLS issue.
>>
>> This was prepared a while back (don't know the actual date but could find
>> out for you). I didn't take the time to reformat the text in this email
>> and
>> the photographs included in the report are not included. See full text
>> below
>> without photos.
>>
>> If you are interested in receiving the full report (text and photos), I
>> will
>> gladly send the PDF to you directly as we can't post attachments to the
>> GSBN
>> listserv.
>>
>> Please let me know your reactions, critique and comments about this
>> report.
>> The specific question is whether or not you feel this would be valuable to
>> the readers of TLS and beyond. A future issue of TLS  (#66) will be
>> focused
>> on various aspects of the bales themselves - types, sizes, properties of,
>> baling machines and equipment, discussion of orientation as bales are
>> stacked, trimming and handling bales, and much more. Seems this might be a
>> good article to include in this issue.
>>
>>
>> Joyce
>> ---------------
>> Joyce Coppinger
>> Managing Editor/Publisher
>> The Last Straw, the international journal
>> of strawbale and natural building
>> PO Box 22706, Lincoln NE 68542-2706
>> 402.483.5135, fax 402.483.5161
>> <thelaststraw at thelaststraw.org>
>> www.thelaststraw.org
>>
>>
>> > AN INVESTIGATION INTO WATER PASSAGE THRU
>> > STRAWBALES
>> > Test conducted and written up by
>> > Tim Rudolph PE
>> > Pinyon Engineering
>> > 115 Eagle Vista
>> > Bishop CA 93514
>> >
>> > Test Goals: to determine how long it takes water to drip thru a
>> strawbale,
>> > how much water is retained and how it spreads as it travels thru the
>> bale.
>> > Test bales in flat orientation and on edge.
>> >
>> > Test Methods:
>> > Water was dripped into the top surface of a strawbale. The weight and
>> > moisture content of the strawbale was measured and then calculated. Once
>> the
>> > water was started dripping on the top of the bale the time to the first
>> > drips to pass thru the bale was recorded. The water was applied to the
>> top
>> > of the bale for 30 min or 15 min at the end of that time the amount of
>> water
>> > left in the application container was measured also the water that
>> dripped
>> > thru the bale was collected and measured. The pattern of the drips
>> leaving
>> > the bottom of the bale was examined during the application time and
>> after.
>> > After the application time was done the drips thru the bale was
>> observed,
>> > recorded and the liquid was collected and measured.
>> >
>> > Strawbales that were tested:
>> > 3 specimens were 2-string rice strawbales from LaGrande Farms in
>> Williams
>> > California
>> > 2 specimens were 3-string (thought to be wheat strawbales from an
>> unknown
>> > source from
>> > the central valley in California purchased at Wye Road Feed & Supply in
>> > Bishop CA.(the
>> > 2 test specimens were from the same bale)
>> >
>> >
>> > Test Configuration
>> > Test Equipment:
>> > New Holland Hay Moisture Meter most accurate under 30% moisture
>> borrowed
>> > from
>> > Strong Arm Construction located in Joshua Tree CA.
>> > 2  Bathroom type scales  with zero adjustment knob
>> > 2 ton engine hoist to hold container to drip water on to top surface of
>> the
>> > bale
>> > Tape measure
>> > Pyrex measuring cup
>> > Test Protocol:
>> > A small hole was punched in the bottom of the 1-gallon container. The
>> > container was
>> > filled with 4 cups of water. The time was measured when the water
>> started
>> > dripping.
>> > Test Data:
>> > Test # 1
>> > 2-string rice strawbale in flat orientation - initial moisture content
>> of
>> > straw =12%
>> > Straw temperature =not recorded (was most likely about 77ºF)
>> > time to first drip thru 53 seconds
>> > water application rate = approximately 0.43 gallon per hour
>> > test time 30 min
>> > water retained by bale = 2 1Ž4 cups water dripped thru bale = 1 1Ž4
>> cups 
>> > total water
>> > applied to bale = 3 1Ž2 cups === 64% water retention
>> > drips thru bale slowed 5 min and then stopped 8 min after the water drip
>> was
>> > stopped
>> > Test # 2
>> > 2-string rice strawbale in flat orientation - initial moisture content
>> of
>> > straw =12%
>> > Straw temperature =77ºF
>> > time to first drip thru 90 seconds
>> > water application rate = approximately 0.46 gallon per hour
>> > test time 30 min
>> > AN INVESTIGATION INTO WATER PASSAGE THRU STRAWBALES
>> > 3of 9
>> > water retained by bale = 2 1Ž2 cups water dripped thru bale = 1 1Ž4
>> cups 
>> > total water
>> > applied to bale = 3 3/4 cups =========== 66% water retention
>> > drips thru bale slowed 2 min and then stopped (not recorded) min after
>> the
>> > water drip was
>> > stopped
>> > Test # 3
>> > 3-string wheat strawbale in flat orientation - initial moisture content
>> of
>> > straw =11.9%
>> > Straw temperature =72ºF
>> > time to first drip thru 100 seconds
>> > water application rate = approximately 0.43 gallon per hour
>> > test time 30 min
>> > water retained by bale = 1 3/8 cups water dripped thru bale = 2 1/8
>> cups 
>> > total water
>> > applied to bale = 3 1Ž2 cups =========== 39 % water retention
>> > drips thru bale slowed and stopped very soon after the water drip was
>> > stopped
>> > Test # 4 on edge orientation
>> > 2-string rice strawbale retied from previous test placed on edge
>> orientation
>> > - initial
>> > moisture content of straw =12%
>> > time to first drip thru 30 seconds
>> > water application rate = approximately 0.68 gallon per hour
>> > test time 15 min
>> > water retained by bale = 1 1/8 cups water dripped thru bale = 2 3/4
>> cups 
>> > total water
>> > applied to bale = 2 3/4 cups =========== 40 % water retention
>> > drips thru bale stopped 2 min after the water drip was stopped stopped
>> much
>> > faster than
>> > bales flat
>> > Test # 5 on edge orientation
>> > 3-string wheat strawbale retied from previous test placed on edge
>> > orientation - initial
>> > moisture content of straw =11.9%
>> > time to first drip thru 50 seconds
>> > water application rate = approximately 0.66 gallon per hour
>> > test time 15 min
>> > water retained by bale = 2 cups water dripped thru bale = 0-5/8 cups 
>> > total water
>> > applied to bale = 2 5/8 cups =========== 76 % water retention
>> > drips thru bale slowed and stopped 2 min after the water drip was
>> stopped
>> > AN INVESTIGATION INTO WATER PASSAGE THRU STRAWBALES
>> > 4of 9
>> > Strawbale Test Photos
>> > Test set up on wheat strawbale- water drip at the center of a flake
>> > Drip pattern of approximately 0.4 gallons per hour
>> > AN INVESTIGATION INTO WATER PASSAGE THRU STRAWBALES
>> > 5of 9
>> > Discoloration of water that dripped thru the strawbale
>> > wheat strawbale on edge long stems run up/down and flakes are 1-2² wide
>> > depending the
>> > alternation of the orientation of the flake (as cut and placed by the
>> > bailer)
>> > AN INVESTIGATION INTO WATER PASSAGE THRU STRAWBALES
>> > 6of 9
>> > Rice Strawbale on edge straw stems run opposite of the wheat strawbale 
>> > Top surface of 2-string strawbale
>> > AN INVESTIGATION INTO WATER PASSAGE THRU STRAWBALES
>> > 7of 9
>> > Exit wound on bottom of 2-string rice strawbale  water migrates to
>> adjacent
>> > flakes as it
>> > pass thru the bale
>> > Dissected 2-string rice strawbale area inside line is where bale is wet
>> from
>> > the water drip
>> > AN INVESTIGATION INTO WATER PASSAGE THRU STRAWBALES
>> > 8of 9
>> > Discussion of Test Data and Test Observations:
>> > Bale Drip Water Retention- from the test data the 2-string rice
>> strawbale
>> > retained about
>> > 60% of the water that was dripped into the bale. The 3-string wheat
>> > strawbale retained
>> > about 40% of the water that was dripped into the bale. Then when the
>> bales
>> > were placed
>> > on edge the rice strawbale retained about 40% while the 3-string wheat
>> > strawbale retained
>> > about 75% of the water that was dripped into the bale. This seems to be
>> due
>> > to the
>> > orientation of the straw stalks in the bale. If water is poured in the
>> ends
>> > like a straw then
>> > it holds more water then when applied across the straw stalk where the
>> water
>> > only has the
>> > small cylinder of the stalk to be absorbed.
>> > This test was prompted by thinking about sill plates and structural
>> design.
>> > The Red
>> > Feather Construction Handbook has the outside sill plate notched with
>> saw
>> > kerfs to allow
>> > drainage. So the question came up as to how does water flow thru
>> strawbales?
>> > So the
>> > test was done to simulate a roof leak.
>> > The 2-string rice strawbale and the 3-string wheat strawbale had similar
>> > patterns
>> > of drip thru. The water entering the bale at a single point on the top
>> of
>> > the bale spread
>> > along the length of the flake and spread to the adjacent flakes. This
>> flow
>> > pattern if
>> > extrapolated to a full wall height the drip in one spot on the top bale
>> > wets 3 flakes then
>> > the next bale below would have 3 flakes with a point source of water so
>> 5
>> > flakes would be
>> > wet(the 3 with the point source then the 2 adjacent them). This would
>> > progress down the
>> > wall effecting more and more of the bales in the wall (this does not
>> > consider the effect of
>> > the bale butt joints). So if a wall is 8 feet tall with 6 bales stacked
>> a
>> > single drip spreading
>> > in this pattern would spread to 18²wide at the base of the wall (using
>> > 2²wide flakes).
>> > The time it might take to exit the bottom bale at 90 seconds to drip
>> thru a
>> > single
>> > bale so 6x 30 seconds =180 seconds = 3 minutes to 6x100 seconds = 600
>> sec
>> > =10 min.
>> > The transit time thru the bale to the bottom of the wall is from 3 to 10
>> > minutes. For the
>> > water to exit the bottom of the wall it needs to get past the sill
>> plates.
>> > The Red Feather
>> > Construction Handbook used saw kerfs in the sill plates to allow water
>> > drainage. The
>> > kerfs are on the outside plates. The saw kerfs are very bad in the sill
>> > plates for structural
>> > reasons.
>> > The sill plates form a dam that would hold water until the plates fill
>> up or
>> > find a
>> > break in the sill plates for the water to flow out of. If the water is
>> to
>> > flow out of the sill
>> > plates in consideration of the transit time and the quick time to stop
>> > dripping it would be
>> > best to aim the water to leak to the inside of the structure so it can
>> be
>> > identified and
>> > corrected. (would this be planning for failure or just the inevitable?)
>> > Allowance of a drainage path thru or around the sill plates would speed
>> the
>> > flow
>> > of water out of the wall. The time it may talk to seep thru a 2x4 sill
>> plate
>> > could be
>> > significant. The use of saw kerfs in the sill plates may be possible but
>> is
>> > not a very good
>> > from a structural standpoint. Using a double laminated sill plate could
>> > solve this by
>> > introducing the gaps for drainage in the lower plate (the lower plate
>> could
>> > be 1Ž4²pressure
>> > treated plywood) while the upper plate carries the structural load.
>> Perhaps
>> > drilling 3/8²
>> > diameter holes at say 4¹ o.c. thru the plate (the long way) to the
>> inside of
>> > the structure
>> > could also be a satisfactory solution.
>> > AN INVESTIGATION INTO WATER PASSAGE THRU STRAWBALES
>> > 9of 9
>> > Failed Test?
>> > I initially ran this test and was discouraged by the quick drip thru
>> time
>> > and how
>> > simple and perhaps uninteresting this test was. Upon speaking of it to
>> > others it was
>> > something they had not thought about. So I set the test up again and
>> took
>> > the original bale
>> > and dripped water thru it. My results were similar to the above test
>> results
>> > but when
>> > tearing the bale apart to examine the area that got wet I found the
>> straw
>> > was discolored
>> > and musty smelling. The test bale had 1 gallon of water dripped thru it
>> and
>> > had been left
>> > sitting in a strawbale garage in August and September in Bishop
>> California.
>> > (typical
>> > temps in the 90¹s to 100¹s with low humidity hot and dry) the bale
>> received
>> > no direct
>> > sun. the bale returned to around the 12% humidity level of the other
>> > (unwetted) bales
>> > stored in the garage. Perhaps this would be typical of a north wall
>> > installation. This seems
>> > to show a wet bale will get funky and stay funky even after drying and
>> may
>> > not show it
>> > on the outside. So, know your bales history from harvest to
>> installation.
>> > discolored bale on second time on drip test- note darkest strip is wet,
>> dark
>> > area is area that
>> > was wet then allowed to dry to 12%, the lighter area is straw that has
>> not
>> > been wet.
>>
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>
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-- 
John Swearingen

Skillful Means
www.skillful-means.com
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