Posted by Deborah (64.230.87.116) on October 19, 2002 at 16:14:51:
In Reply to: What at my Options? posted by John Franklin on October 18, 2002 at 14:12:34:
: My wife and I have a small organic farm in Michigan that we are operating as a CSA (Community Support Agriculture). I’m about it assemble a greenhouse for some cold tolerant crops as well as a place to start transplants. This spring we had about 1,200 plants in our basement and it could double next year. The problem is with the typical tube framed, poly covered greenhouse there is some would in the construction. Often pressure treated lumber is used around the perimeter in contact with the ground. This is not acceptable for organic gardening but I’m told that if I keep the pressure treated lumber off the ground it will meet requirements. Even this is not acceptable for me. There will be some water run off and therefore the possibility of the persevere leaching out and getting into our soil.
: I must use a lumber type material but need a longer life than standard woods will give. I have checked into cedar but find it very expensive and hard to get in the sizes I need. Seeing that CCA’s are being phased out soon for residential use are there any reasonable, cost effective, safe substitutes available at this time. If so where would I find them? I realize that new things sometimes cost more but cedar is about three times the money and will not last as long as the current pressure treated products.
: Any help would be appreciated.
: John Franklin
Hi John,
I am very glad to hear that you do not find the use of cca wood acceptable. Actually after Dec 31 2003, cca wood is not allowed to be used in residential use and many other applications and I would have to check if this would even be allowed after that time.
The hypocrisy of course is that the governments are not dealing with existing structures built before that time.
I think you will find as the public becomes more aware of this issue that fewer people would be interested in your product if cca wood were used.
There is posted on my articles page a study by Dr David Stilwell on the uptake of arsenic by plants.
David and others including the University of Melbourne continue to study this issue and it is becoming increasing clear that we cannot control the variables enough to use this wood safely.
That said ,you have to decide what kind of alternative you would wish. There are several chemical ones including acq. Acq lumber is not much more expensive and its main ingredient is copper which is a bad choice for aquatic environments as it leaches worse than cca in water. However this application would not be the same thing. Boron from most things I have read is one of the safest of treatments that use chemicals.
However you could use pine and replace it more often if that met your building codes or you could use a vinyl wood replacement which would be very expensive but would last a very long time or turn to something like the lanolin product from Australia which treats wood naturally and I have been told that if re applied will keep cheap woods lasting a very long time.
Wood that is kept off the ground does usually not decay the way it does with contact. CCA wood was originally produced for in ground contact and people just got carried away. In the Uk they took ten boards of various or no treatments and placed them outdoors off the ground. Ten years later none of the boards had any sign of problem, except the cca which cracked and split. Perhaps we just may be being mislead a little about the truth of treating wood.
Lastly i want to mention that cca should never be used indoors.
While cedar is expensive you might find a local mill who would cut to the size needed, they are also cheaper and perhaps you could barter some of your crop in exchange.
If you need anything else, send me an email or post here again and good luck with your business.
Take care and please keep safe John.
Deborah