[Greenbuilding] best lumber for raised vegetable beds

[Tim Vireo Keating]

Sorry for the delay on this postŠ

And we call ourselves green builders, yet we seem 
either unable or unwilling to look into this any 
deeper than the very surface: "plast-eccchhh!". 
There are many types of plastic. Some are durable 
outside, some are not. Some are 'strong' in terms 
of modulus of elasticity, some are not. Some are 
'strong' in terms of modulus of rupture, some are 
not (think, for instance, of those damnable 
plastic chairs - ever try leaning back on one - 
how many have we seen at the curb with three 
legs?).

Here's just a simple, simple run-down (and I know 
you've all seen this in some way or another):

#1: PETE or PET (polyethylene teraphthalate) - 
soda bottles and some take-out containers, etc.
#2: HDPE (high-density polyethylene) - detergent, 
shampoo and motor oil bottles, etc.
#3: PVC (poly-vinyl chloride) - venetian blinds, 
stiff water pipes, shower curtains, etc.
#4: LDPE (low-density polyethylene) - yogurt and 
other container lids, some plastic bags, etc.
#5: PP (polypropylene) - yogurt containers, other 
take-out containers, plastic bottle caps, etc.
#6: PS (polystyrene) - Japanese sushi take-out 
containers, Styrofoam and other foamed take out 
containers, etc.
#7: Mixed - "Nalgene", etc.

Each of these plastics has different properties 
and also produce different pollutants in their 
original production. PVC will also generate 
pollutants each time it is melted. HDPE and PETE 
will not. HDPE, PETE and PP are considered 
non-reactive.

True RPLs use HDPE because it is readily 
available, less expensive that PETE (which has a 
pretty good market for fleece and some bottle 
remanufacturing) and is extremely durable in the 
outdoors.

All of the 'true' RPL manufacturers of which I 
know ues post-consumer plastic and thus spare 
this material from going to a landfill. Then 
these materials are substituted for, among other 
things, wood logged from old-growth forests (even 
if it's not in the tropics, Western red cedar, 
cypress, Douglas fir, Alaskan (yellow cedar) and 
redwood are North American woods coming from 
temperate rainforests or subtropical forests and 
are, if they are clear (the only grade that will 
truly last), they are being logged from the last 
of the old growth of the forests in which they 
occur.

Thus, RPLs are an amazingly green product.

tim keating


At 2:15 PM -0400 4/14/11, RT wrote:
>>Why does it have to last 40 years?
>>What's wrong with using something natural and replacing it every 10 - 15?
>
>>The problem with cedar that will actually last 
>>40 years in ground contact is that it is likely 
>>from old-growth.
>
>>RPL is often the way to go when looking for 
>>durability in exterior applications.
>
>Years ago (20 ?) when garden tools first started 
>appearing with plast-eccchhh! handles I bought a 
>bunch (some D-handled spades, forks, hoes, 
>cultivators etc) thinking that they should last 
>forever without my having to do the yearly 
>treatments with linseed oil that I do with my 
>wooden-handled tools.
>
>The plast-echhh ! seemed like a good idea 
>because I thought that I would be able to leave 
>them out in the garden in between uses and have 
>them right where I needed them.
>
>Of course, I should have known better because 
>*NOTHING* that I've had that was made as a 
>plastic substitute for the real thing (wood, 
>metal) has ever lasted.
>
>If it's not deterioration as a result of UV 
>exposure, it's shattering due to brittleness in 
>cold weather or it's being chewed to bits by 
>some little buck-toothed furry critters thinking 
>that it was food .
>
>It was the middle of January or so just this 
>past winter when I grabbed a 
>plast-ecccchhh!-handled spade from an open-sided 
>shed (rather than dig out the feets of snow in 
>front of the door of a garden shed) to do some 
>quick digging...
>and the danged thing snapped off right where the 
>plastic shaft enters the shank of the blade. 
>@&^#@#*#&(@# eh ?
>
>OTOH, I still have/use some wooden-handled 
>garden tools that my Mom used to use in her 
>garden.
>
>As for plast-ecchhhh! lumber:
>
>Many of my neighbours used plast-ecchhh! lumber 
>for their decks. You know, the stuff that costs 
># times what real wood costs.
>I have yet to see one that hasn't experienced 
>cracking and splitting, one (much to the alarm 
>of my neighbour) splitting in as little as over 
>the course of the first winter.
>
>
>But back to the subject at hand:
>
>I'd suggest that salvaged-from-a-nearby-source 
>(ie within 5 miles or less) concrete block would 
>be one of the better choices for the task of 
>coralling the soil in raised vegetable beds. I 
>was fortunate to have a fellow just three 
>sideroads up from me, deconstruct an old dairy 
>that was on his property. Nice, limewashed, 8"x 
>8" x 16" three-hole CMUs (ie thicker walls and 
>webs than the modern 2-holed CMU), stacked 
>neatly so all I had to do was back up my truck 
>to the stacks, fill up my truck and take 'em 
>home.  And he wouldn't take any money from me 
>either.
>
>There are usually any number of sources for 
>salvaged CMUs if one lives near a large-ish 
>urban centre because there are always developers 
>tearing down old buildings to throw up condos or 
>strips malls etc.
>
>The problem with CMUs is that they're heavy so 
>if you're hauling them with something like a 
>pickup truck & trailer, it doesn't take all that 
>many to make up a tonne or two so you really 
>don't want to have to make a bazillion long 
>drives back and forth to haul them home, hence 
>the "5 mile (or so): criteria stated earlier.
>
>Even better would be to have the deconstruction 
>contractor have their backhoe load the blocks 
>into their dumptrucks and deliver them to your 
>site, usually at no charge other than maybe some 
>coffee and doughnuts to coerce them to dump at 
>your site rather than some other site.
>--
>=== * ===
>Rob Tom
>Kanata, Ontario, Canada
>< A r c h i L o g i c  at  Y a h o o  dot  c a >
>manually winnow the chaff from my edress if you hit "reply"
>
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-- 


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measure of our bodies are the same..."
     	                               - Hinmaton Yalatkit, Nez Perce chief
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