What Is Pressure Treated Wood?

When wood is put in a pressurized tank, where the air in the wood is removed and replaced by chemical preservatives to lengthen the life of that wood and save it from insects, mold, and more, that is what is pressure treated wood or PT wood.

The tank is a pressure chamber called a retort and the technique uses up to 160 pounds of pressure to push the chemicals into the grains of wood. PT wood takes its own time to completely dry depending on the weather that it is exposed to. The time could vary between a few weeks to a few months.

This wood needs to be entirely dry before a stain or paint is applied to it. If the wood has not dried properly, the paint job or stain job shall fail. We shall talk more about this as we go further.

The How

When they initially patented the method, Arsenic was heavily used. Arsenic, if swallowed by humans, is known to cause cancer. 
Hence, it has now been replaced with a copper-based preservative. 
You can identify pressure-treated wood with the slightly greenish, patina tint that it has.
However, this tint fades away with time.

The Why

In the 1900s, lumber companies realized that pressure-treating woods helped prolong the life of wood even when it was exposed to water and could also prevent insects from invading and damaging it.

The Pros

PT wood has its own benefits, despite all the controversy around its usage. Let us look at some of the many benefits of pressure-treated wood.
  • PT wood is 30-40% less expensive than other types of wood. 
  • It is stronger and shall stand the test of time. For a lower price, you get wood that lasts longer.
  • It is safe from insects and can even be exposed to water, it shall not be affected.
  • It is low on maintenance hence it is inexpensive to manage.
  • Even after many years, it will still look the same.
  • PT wood is termite-safe and pest-free.

The Cons

PT wood has many chemicals that are used on it and these can prove to be very harmful when used inside a closed home. The toxicity levels may vary depending on the use of and quantity of chemicals. These are very important while understanding what is pressure treated wood.
  • These are known to have adverse effects on the respiratory systems of those inhaling them every day. It has also been known to have had side effects like skin and eye irritation, even cancer.
  • If the chemicals are of a flammable nature, a small fire in the house could lead to a major disaster, all thanks to this chemically treated pressure tested wood.
  • If a human were to come in bare contact with toxically treated wood, it could also seep into the pores of human skin, causing severe allergic reactions.
  • If chopping boards are made with pressure-tested wood, those chemicals could mix with food and if orally ingested, it could lead to many digestive disorders. Using pressure-tested wood around food could be of major concern.
  • If children were to breathe in the fumes, there could be fatal injuries too.

Indoor Use - Yes or No?

There are many who defend the use of lumber indoors and there is an equal number who stand strongly against it. Here we shall discuss both sides and help you make your decision.
  • It is believed that as the wood ages, those chemicals and preservatives that were forced into it start surfacing and can be very dangerous to those breathing that air.
  • A newer method is to use ‘Borate wood’ indoors wherein the wood is pressurized with borate instead of chemicals. Borate is a naturally derived mineral from water, rocks, and soil. This kind of wood is believed to be safe to use indoors as long as it is not used around food. So, no chopping boards, kitchen countertops, and dining tabletops for sure.
  • While handling borate wood, the handler must be wearing gloves, be covered, and have a mask on the face. Hence, some people argue that this goes on to prove that it is not healthy to be used indoors.

Stain it

Ultimately, wood is a part of nature and so it must be protected to maintain it. 
Staining a wooden deck with a stain sealant helps to maintain the look of the wood for years. We recommend using an oil-based sealant to get the best effect.

Some argue about whether to wait after pressure treating the wood and some confirm that it must be done immediately after the treatment. 
This decision entirely depends on the surface and expert opinion may be sought here.

PT wood sometimes has a green patina finish because of the use of copper metal, which needs to be scraped off before using a sealant. Also, this process needs to be redone annually. 

Paint it

PT wood takes very long to dry and it cannot be painted before it is completely dry.
Try spraying some water on this wood and if it is absorbed, then this wood is ready to be painted.
  1. You must clean the area with soap and water and then dry it completely. This step must not be skipped as it is important to clean the area carefully before painting it.
  2. Use a good quality oil-based primer as they seep deep into the wood. 
  3. Follow this step by applying at least two coats of paint.
  4. Do not paint in a very hot or humid environment as that may adversely affect the application.
  5. You may use a spray or even hand brush the paint on your PT wood.

Turning Gray

If a sealant is not used, this wood shall begin to turn gray. This shall happen to all pressure-treated wood that is unstained.
To make the wood look new again, you may scrape the areas where there is discoloration. 
You may also use an oxalic acid solution to the entire area to help make the wood look like its original hue.

Stay Safe 

  • Make sure you wear gloves, a mask, and eyeglasses while handling pressurized wood.
  • Use a tablecloth on all dining tabletops to avoid any contact with pressure-treated wood as it could be harmful to ingest food that could have been contaminated by coming in contact with the arsenic or copper on PT wood.
  • Keep children and pets away from PT wood to avoid any mishaps.
  • Make sure you wash your hands thoroughly with soap and water after being around PT wood.
  • Do not burn PT wood as it could release harmful fumes.

We hope this article tells you all that you need to know about what is pressure treated wood, the benefits, and disadvantages of using pressure-tested wood, indoors and outdoors while educating you on the safety measures while dealing with pressure-treated wood.

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