I am getting varied recommendations about sealing PT plywood that covers part of my below grade foundation. The Arch suggests removing it all (very costly), a GC recommends sealing it. Another says just leave it as is. Another wants to cover with a foam panel and stucco or face it with a veneer product.
Does anyone have thoughts on the above and can you make a recommendation on what products can seal the lumber? Epoxy paint…bitimuem (sp?) rubber…etc. I have to make a decision soon and want some more feed back.
Thanks in advance
Doug
Replies
what does a local termite expert say?
if termites are a problem in your area?
wood below ground?
It is a PT foundation, popularized by Frank Lloyd Wright and used in the Mid-west and alaska. I am replacing an area that was not far enough below grade. The rest I want to keep but would like to seal the PT wood to prevent the arsenic from leaching into the soil.
It is 4' deep so I want to have a GC excavate, seal with a product, replace the perimeter drainage, and cover back up.
I am just unsure what to use as the sealing product; the GC's I've talked to don't seem to have any consensus on this.
If that's your only worry, just use paint or an asphaltic emulsion made for foundations.
The two things that can release the arsenic to be free agaent in the soil where it might be bad for you are heat and acidic conditions.
If your house burns down, the heat will release the poison but you will have other things to worry about then and the sealant won't make any difference. Most soils are not acidic enough to cause leaching but if hyou have a highly acid soil that stays wet right there, it might leacha little out. That's why you don't want PT for a veggie garden along with manure. Just a layer of paint or asphalt will separate the acidic water from the PT ply
Too much is made of the dangers of PT lumber, IMO. There is arsenic in most soils naturally. Some more than others. No danger or causal effects could be shown in court but the industry decided that it was an expensive thing from both legal and PR viewpoints to keep marketing it so they agreed to a reduction in production. It was political rather than scientific..
Excellence is its own reward!
It was political rather than scientific.
Mostly, but not completely. The big flap was over tests in florida showing that children playing on CCA treated playground equipment were getting a measurable amount on their hands. Other studies show that people exposed to arsenic in drinking water high a much higher incidence of certain types of cancer. The supposition was that the children playing on the PT treated playground equipment would have a slightly elevated chance of developing cancer over their lifetime. Modern epidemiology methods probably are not sensitive enough to gauge just how many will be effected and it will probably only be a few. Still, do you want your kid to be one of those few.
The other opposition came from municiple incinerator operators who end up with a sufficient quantity of arsenic from PT lumber that they have to handle the ash as toxic waste.
And, there is the oft told tale of the farmer who burned some PT lumber in his field and then had his cow die of arsenic poisoning when she grazed in that area.
But overall, the increased risk of cancer is probably far less than that from still legal (at least in some areas) second hand smoke...
I certainly agree about the playground thing. It needs to be dried and sealed if used for playground equiptment but even then - well you know how little kids will chew on anything...
but overall, it's been an over-reaction.
Excellence is its own reward!
Thank you very much. Your info is helpful!
What's the plywood doing there? And what kind of foundation is it?
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