Pressure treated wood is very soft and is usually very wet when bought, so it will shrink and warp the most compared to other options. It is widely used as a fencing material for pickets and structural 2×4 and while it maybe all some can afford, it will cost more in the long run.
A pressure treated fence will start to warp very quickly, I have personally noticed this happen hours after purchasing the material. The 2x4s will droop within months and before you know it your fence looks like something out of a van gogh painting.
To add to this, pressure treated wood needs to be properly disposed of. The chemical currently used in residential applications is Alkaline Copper Quaternary. This chemical is a pesticide and cannot be burnt, as doing so will release the harmful chemicals into the air that are toxic if inhaled and the ash is very toxic.
Since the 1940s until 2003, Chromated Copper Arsenate was used to treat wood, which included arsenic and poses cancer and non-cancer health risks.
While newer wood treatments are less toxic than its predecessors it still poses health risks to our ecosystems and potentially harm your pets.
Pressure treated wood fencing could potentially save half the initial investment, in my experience it will last 7-10 years at most. It is a very soft wood and degrades quickly compared to cedar fencing which will last up to 20 years if maintained. There are some climates where pressure treated wood will last longer, if the potential health hazards are disregarded, and maybe a better option.
Alternatives
Imported Cedar, Japanese Cedar, or CRC cedar is essentially all the same. This type of cedar will always be kiln dried because the process makes it much lighter and more inexpensive to ship. Imported Cedar still retains the same oils that make it cedar. The drawbacks with imported cedar are the life span is unknown due to being so new to the market and the wood is much more prone to warp than its domestic counterpart.
Whitewood
Whiewood is another alternative that is cheaper than western red and is widely used for fencing as well due to its price. These pickets will generally be thicker, but are not treated like pressure treated pine. With it being a very soft wood, it is prone to decay rather quickly.
Why Choose Western Red Cedar?
Western Red Cedar is the preferred option because it is all natural. There is no need for added chemicals because the natural oils in cedar repel bugs and sheds water. Not only is it better for the environment, it looks better, warps much less, and smells pleasant.