When To Use Pressure Treated Wood

When to Use Pressure Treated Wood?


Wood is naturally vulnerable to the elements. When left untreated for so many years, wood can rot, develop molds or be infested with wood boring pests. Wood is undoubtedly beautiful, no matter what species of wood you may have. But sometimes, it needs good old TLC to keep it rot and pest-free.

Pressure treating wood

Usually, the first thing that you think about when using hardwood or any type of wood for any project is the species of wood that you would use. Once you made your choice, the next thing you might think about is the quality of that wood and this is where pressure treatment is important.

All types of lumber, from the common 2 x 4 to specialty plywood, is either pressure treated or not at all. Pressure treatment makes the wood last longer. It prevents rotting and insect infestation. But will all the good qualities of pressure-treated wood, come the bad. The chemical used to treat wood is known as one of the most toxic.

Direct moisture contact

You must use pressure treated wood where there’s direct contact between wood and anything that has moisture. Wooden posts in contact or buried underground can be affected by moisture. Therefore these should be made from pressure-treated wood since this can resist moisture better.

The International Building Code requires that siding and structural lumber used on the last six inches of the structure above ground should be pressure-treated wood. You must also consider pressure treated wood for building subflooring in the kitchen and bathroom since these may be prone to moisture due to water leakage.

Avoid contact with people and pests

The chemical used in pressure treating wood is not safe for humans and to pets. This chemical is composed of arsenic especially in all older pressure treated lumber and some new materials. Copper is also used in the newest pressure treatment formulas and does not pose threat to health, unlike arsenic.

You must exercise caution when touching or picking up wood. Never touch pressure-treated wood and rub your eyes or eat with your hands because you may ingest poisonous arsenic. This is also true for pets especially dogs or cats that live with you indoors.

Because of its severe effects on health, non-pressure-treated wood is used indoors and pressure treated lumber is used only for the support structure of a deck while untreated wood is used to construct the deck’s surface.

Take note that anywhere inside the house pets and kids spend time regularly should be built with non-treated wood including decks, beds, play sets, tree houses, gardens and more. Cedar is a good alternative to pressure-treated wood because it has rot-resistant properties and is pest-resistant as well.

Applying protective sealant

If you must use pressure-treated wood because you need strong material to make posts, supports and floors then there is no other choice. It’s better to use treated lumber and be at peace knowing your home is secure than to use untreated wood for the supports and have these rapidly rot away. The last recourse is to use pressure-treated wood that has been treated with an oil-based sealant.

Oil-based sealants can reduce the amount of dangerous arsenic, copper, and other toxic compounds from reaching the surface of the wood. Because the most common way to ingest the toxic substance is by touching and using your hands afterwards then a sealant is a suitable barrier between you and wood.

You don’t need to apply sealant on pressure-treated wood used for building subflooring and supports because pressure treated wood doesn’t release any gases or particulates that can pose any risk. You will have nothing to worry about for as long as you are not touching the wood or exposed to its sawdust then there are no risks at all.

The oil-based sealant should be applied periodically on pressure-treated wood for the entire life of the structure. You must never forget this treatment if you have this kind of building material at home.


Pressure treated lumber is resistant to mold, water damage, and pests. A very toxic chemical is used to pressure treat wood and this is dangerous for animals and humans. This is why you must consider closely whether you need pressure treated wood or not for your project and if you are up for pressure treated wood, you must periodically use a sealant to protect you and your family.

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