Pressure-treated lumber is the least expensive product that you can use on an exterior deck.
It is about 35% less expensive than redwood and lasts twice as long. There are differentqualities of pressure-treated lumber. Most people use number 2 grade lumber. There is a product that is kiln dried called KDAT and it is a select lumber and about 20% more expensive than the number 2 grade lumber.
Pressure Treated Wood is considered poisonous to insects, fungus, and bacteria and to humans and other forms of life.
It is a carcinogenThe wood is manufactured using copper, chromium, and arsenic which are known hazards to humans and to the environment and do not break down into harmless substances.
The manufacturers do claim that the compounds are chemically locked into the wood, and therefore do not present a hazard to human health or the environment. The real issue is when this wood is burned. By burning the wood, arsenic is released in a highly toxic level. This would should never be burned due to the dangerous conditions and the toxicity.
Due to the contamination issues of CCA-treated wood to the surrounding environment, one should never have a garden close by and should always be cognizant not to allow children to play in the dirt where leaching may take place
This product is typically disposed with the rest of construction waste and is not properly handled, which means that it will continue to contaminate the environment.
All that being said pressure-treated lumber represents an excess of 80% of the materials used on exterior decks. If you plan to keep your house for 10+ years then I would recommend using an alternative product that will give you a better return on your dollar and a longer term solution.