Pressure Treated Plywood

[Larry Robinson]

Looking to build some benches for outdoor use with pressure treated plywood. I am concerned that the plywood might delamintate with outdoor use.

Would it help to coat the wood/edges, if so, what would be best?

Any suggesttions would be welcomed.

Thanks
Larry

[Roy McQuay]

I use pt plywood for a wheelchair ramp for my wife. The ramp is short, only about 6" rise over 6' long. When I built it, I just figured on replacing as necessary from deterioration. So far, after 5 years, it hasn't changed much. I know this isn't the answer you were looking for, but I thought it might help. The ramp gets a lot of use and I have never treated it or put any finish on it.

[Anthony Smaldone]

I have built about a dozen wheelchair ramps for customers over the years. So far I have never been called back. (all were built with pressure treated ply). 2 were built over 10 yrs. ago.

[skip coyne]

I would be concerned about sitting on PT

[jason lambert]

Yes PT is not good when in contact with the skin, it can posion you. Also plywood tends to splinter when it gets old outside. Just my thought. Might help if you posted a pic of what you are planning to do.

[Ted Miller]

Talk about fester and infection, splinters from Wolmanized wood is the worst in your system. Treated lumber has Chromic and Arsenic acids, Copper Oxides and Formaldehyde. Always use a mask when cutting this stuff as well even if outside.

I used to build seewalls back east and they had treated 4x and 6x that would last 50 years in water, crazy...

[Randy Denby]

I have a piece of the older type PT plywood that I made a v shape with and about 20" tall. I used it to block the dryer vent from the shrubs. Its been theRe since 1993 and still looks good. And this with one end just sitting on the ground. Good stuff !

[Cliff Rohrabacher]

PAINT 'EM~!! I am building a set of Adirondack chairs from PT. I like the thickness of the lumber it was cheap and the bugs and rot won't get them.
However, the material MUST be sealed really well if it's to be used as furniture.

The single best sealing material I have found is a two component catalyizing urethane. I believe you could just let the wood dry out comepletely and then paint it but you'd have to wait for that. The urethane can go on slightly damp lumber just fine.

[Greg Cuetara]

Maybe someone can correct me here but I thought they had to get rid of all the arsenic out of PT and it is all 'safe' now. As safe as it is going to be. I thought there was a real problem with kids playsets and the PT so they had to change it all to some new chemical treatment which is much safer...

[Joe Diggs]

"On February 12, 2002, the United States Environmental Protection Agency (EPA) announced a voluntary decision by industry to move consumer use of treated lumber products away from a variety of pressure-treated woods that contains arsenic, in favor of new alternative wood preservatives. This transition affects virtually all residential uses of wood treated with chromated copper arsenate, also known as CCA, including wood used in play-structures, decks, picnic tables, landscaping timbers, residential fencing, and boardwalks. As of January 1, 2004, EPA will not allow CCA products to be used to treat wood intended for any of these residential uses."

However..

"The most common alternate treatments are Alkaline Copper Quaternary (ACQ), Copper Azole and Sodium Borate. According to the lumber and fastener industry, the newer chemicals being used to treat the wood approved for outdoor use may be considerably more corrosive than those previously treated with CCA and therefore require special fasteners, hangers and greater care in the selection of materials that may come in contact with the wood.
Designers, builders, supplies and Building Officials will need to pay particular attention to the grade marks on the lumber, and verify that proper hardware (hangers, nails, brackets) is appropriate with the particular treatment of the lumber."

[Dave Lindgren]

Does this mean you can still get cca treated wood for architectual use? I built a pole house in the mid-70's, and we never had a problem with the cca wood. Or ants. They would crawl a foot up the pole, and drop off dead.

[Cliff Rohrabacher]

Designers, builders, supplies and Building Officials will need to pay particular attention to the grade marks on the lumber, and verify that proper hardware (hangers, nails, brackets) is appropriate with the particular treatment of the lumber."

From what I understand the SST screws the sell at the BORG are inadequate and will begin to rust when exposed to the boric acid in the newer PT wood. I haven't seen it yet but I do know that the SST they use is pretty crummy and soft.


And for whatever reason PT splinters are still among the nastiest splinters going.

[Joe Chritz]

CCA is still available for ground contact as far as I know. It is used in wooden foundations often. 4x6 poles and bigger are still CCA, at least they were when I built my shop 2 years or so ago.

The "danger" of CCA is mostly hype and sensational press. Still sitting on plywood of any kind, especially that is left outside is not comfortable.

I know of CCA plywood that was used for trim on a wooden foundation 20 years ago that is still in great shape. The bottom several inches is buried with about 12 above ground level.

For benches I would look at other stuff first but CCA plywood won't fall apart if it fits what you want for looks.

Cliff is correct that the dust can be harmful if ingested, as can any other and the slivers are terrible.

Joe