DIY and Pro Help With Your Home Projects

How To Use Pressure Treated Wood

Pressure Treated Wood
Lumber produced before January 2004 used Chromated Copper Arsenate (CCA) as the main preservative. Prior to 2004, the US was consuming over 40 million pounds of arsenic per year with most of this going into pressure treated wood. Both the chrome and the arsenic in this compound were found to have health risks so Environmental Protection Agency (EPA) forced manufacturer to find another safer solution.

Two new solutions are Alkaline Copper Quat (ACQ types B and D) and Copper Azole (CDA-A, CA-B) These new low-toxicity compounds are sold under various trade names including Preserve, NatureWood, and Natural Select. These compounds have been around for years but were not popular because of their high cost. Now with no other option, they are the standard.

The high level of copper in modern pressure-treated wood has 2 main drawbacks. The copper itself is expensive and this has driven up the cost of PT lumber. The second drawback is that the high copper content can cause a galvanic reaction with common construction metals.

Both aluminum and steel are highly reactive with copper. Galavanized steel is also mildly reactive. The result is that installing pressure treated wood on decks and other structures is more difficult and expensive. (The good news is you will live longer).

Here are the new rules for deck building with new PT limber:

Do not use aluminum flashing for the ledger board. The best option is copper sheet but thick galvanized steel is still acceptable. You can also use membrane flashing.

Joist hanger should have a triple zinc coated. Regular joist hangers look similar but can corrode quickly when exposed to pressure-treated wood. The thicker galvanized hanger are currently the best option for pressure-treated decks

Do not use carbon steel or hot galvanized hardware as it will rapidly corrode. The best hardware option is stainless steel screws or nails. The next best option is hot-dipped galvanized followed by polymer coated harware.

You still need to wear glove and a mask when working with PT lumber (especially when cutting it)

You can dispose of scrape lumber by taking it to the dump. There are no special disposal requirements in any states that I know of. Do not burn PT wood as it still produces toxic smoke and ash.

Another CCA replacement is Disodium Octaborate Tetrahydrate (DOT). Borate taken into the body doesn?t accumulate like heavy metals. This solution is marketed as Envirosafe Plus lumber. The advantages include noncorrosiveness, fire suppression, nontoxic smoke when burned, and almost no risk to pets and children. The downsides are the borate can leach from the wood and the wood may not be as resistant to weather, mold, and insects.


In California, PT cannot be disposed of in the landfill! It is a HHW (Household Hazardous Waste) and must be properly disposed with a HHW licensed contractor OR by a level 2 landfill (of which I know of only 1 in Northern California - Hayroad and 113s in Dixon)


The information on this site is provided for reference only and is provided "AS IS", "AS AVAILABLE" with no guarantee of accuracy. Information comes with no warranties, express or implied. Use the information from this site at your own risk. See our disclaimer for more details.