Working with Treated Lumber: Safety Precautions and Best Practices
Planning a DIY woodworking project for outdoor use? You may want to consider using pressure-treated lumber rather than untreated wood. Doing so can help the structure last much longer!
What is treated wood? It’s lumber that has had certain chemicals and preservatives applied to it to protect it from decay, bugs, and other hazards. If you choose to use this kind of wood, keep safety in mind. We’ll explore treated lumber in more detail — including how to stay safe while working with it!
What Is Pressure-Treated Lumber?
It’s wood--typically southern yellow pine--that’s been treated with specific preservative chemicals to extend its lifespan and guard against certain dangers. Wood can be a strong, durable material to use for building, but it’s also vulnerable to:
- Termites and other wood-boring bugs
- Decay-causing fungi
- Marine organisms
- Structural degradation
- Rot from exposure to water and excessive moisture
Treating wood with chemicals helps lower these risks. A few that you’ll commonly find in treated lumber include:
- Copper azole
- Alkaline copper quaternary
- Micronized copper azole
Types of Treated Lumber
Treated wood is commonly known as pressure-treated lumber because it undergoes high pressure that forces preservatives deep into the wood fibers — giving it greater protection from destruction and decay.
There are two basic types of pressure-treated wood:
- Ground contact: Wood that can be used in contact with the ground, such as fences
- Above-ground use: Wood that’s used in above-ground projects, such as a decking
Ground contact treated wood has double the level of protection than above-ground use wood. It needs it due to the increased risk of exposure to fungi and bugs in soil.
Above-ground use treated lumber is designed for using at least 6 inches above the ground. It doesn’t have the same amount of protection as ground-contact lumber.
Uses of Treated Wood
What can you use treated lumber for? It’s a good choice for a lot of outdoor DIY projects. But note that it can’t be used indoors due to safety issues. You can build or make all kinds of outdoor structures with treated wood, such as:
- Fences
- Decks
- Walkways
- Picnic tables
- Ramps
- Docks
- Garden beds
- Retaining walls
Using treated wood helps extend the lifespan of anything you build. For comparison, untreated lumber can start to degrade or rot in just a couple of years — or even sooner if it’s exposed to a lot of bugs or fungi.
Why Treated Lumber Warps
This kind of lumber does last longer than untreated wood. But being treated with chemicals doesn’t stop it from warping. Why does this happen? It’s due to grain patterns that develop as trees grow. Wood cut from trees has irregularities that can lead to warping.
Is there a way to prevent this? Storing treated wood properly before using it may help keep warping to a minimum. Also, try to avoid buying treated wood that's saturated and soggy. Boards that have already dried out--and remained straight--are less likely to warp.
How to Correctly Work With Treated Wood
Before reaching for your saw, it’s important to understand how working with pressure-treated wood differs from using untreated wood. The chemicals used to protect against bugs and other hazards can cause safety issues if you’re not careful.
Working with any kind of wood creates sawdust. But dust from treated lumber contains potentially harmful chemicals. That means you’ll need to take more precautions when sawing, cutting, sanding or carving. And you’ll need to carefully clean up your work area and properly dispose of all treated wood debris.
What about working with pressure treated wood? Note that this kind of lumber can be damp or wet if it’s been treated recently. You’ll have to give it time to dry before working on it.
What about tools? Make sure that any tools you use are suitable for working wood. They should be sharp enough and in good condition to reduce the risk of splintering and other damage.
Safety Precautions
Is pressure-treated wood safe? Yes — when it’s used correctly. Again, you’ll want to avoid using it for any indoor projects, especially for cutting boards, counters, or any surface used for food prep. When you work with treated lumber, always follow these safety precautions.
Work Outside
Set up your work area outdoors. Working with treated wood indoors — even in a well-ventilated area — puts you at risk of exposure to the chemicals used to treat it. This is especially important when you’re doing any sanding or cutting.
Cover Exposed Skin
That goes for your arms, legs, and hands. Sawdust can coat exposed skin, increasing your risk of being exposed to chemicals in treated wood. Wear a long-sleeved shirt and long pants when you’re working with this kind of lumber. Put on a pair of gloves to protect your hands from treated wood chemicals — and sharp tools!
After you’re done, wash your clothes separately to remove all traces of chemicals. And remember to wash your hands afterwards — even if you wear gloves.
Wear a Dust Mask
Working with treated lumber means you’ll have dust and debris all around. Breathing it in causes it to get into your lungs. This isn’t good in general. But it’s even more of a hazard with treated wood due to the chemicals in it.
Put a dust mask on while working with this kind of wood, whether you’re sawing, sanding, cutting, or carving. If you use disposable dust masks, throw them out after each use. No matter what kind of dust mask you use, make sure it fully covers your mouth and nose.
Dispose of Debris Properly
After working on your project, you can expect to have lots of dust and debris around. You might also have extra scraps of wood. Dispose of them safely by:
- Sweeping or vacuuming up debris and dust
- Putting scraps in a trash bag, along with dust and debris
- Taking trash bags to your local landfill
What should you avoid doing? Don’t burn treated wood scraps! This releases chemicals into the environment. And don’t spread debris and dust around in your garden as mulch. The chemicals in it make it dangerous to pets and wildlife.
FAQs
How to paint treated lumber?
Interested in changing the appearance of treated wood? You might want to do this to give your yard a fresh look with a painted deck or fences. But how do you go about painting treated lumber?
You’ll need to wait until it’s dry. That might involve waiting several weeks — or even months. When your wood surfaces are dry, apply a latex primer first. Then, use water-based paint to give your treated lumber a new color.
How to stain treated wood?
This type of lumber is safe from bugs and rot. But dirt and exposure to the elements can still take a toll on it. Applying stain may help extend its lifespan — and make it look better overall. As with paint, you’ll have to wait for treated lumber to dry before staining it.
How do you know when it’s ready? Sprinkle a bit of water on it. If the wood absorbs the water, it’s dry enough to stain. But avoid staining it in direct sunlight or on humid days. You’ll get better results doing this on dry days in indirect sunlight.
Is treated lumber water-resistant?
Not on its own. The chemicals in it can help it resist rot, decay, and even fire damage — but they don’t stop water from getting inside it. Treated lumber needs a water-repellant sealer to keep it safe from moisture damage.
Note that you may need to wait a few weeks or more for pressure-treated wood to fully dry before applying a penetrating sealant. Once it’s sealed, you should apply a fresh coat each year. This helps protect treated wood from cracking or developing other kinds of moisture damage.
If you’ve stained treated wood, you probably don’t need to seal it. Most stains used on exterior surfaces include sealant.
How long does treated lumber last?
That depends on a few factors, such as:
- Your local climate
- Whether it’s regularly maintained
- What you’re using it for
Treated wood can last for decades, especially if it doesn’t get a lot of wear and tear over the years. But it might have a shorter lifespan with certain uses. A deck that gets a lot of foot traffic might not last as long, for example.
Cleaning treated lumber and applying a penetrating sealer to repel water can help it last longer.
Treated lumber offers a great way to build outdoor structures that stand the test of time. You don’t have to worry about termites eating their way through it. And you don’t have to deal with wood rot.
But you do need to keep pressure treated wood safety precautions in mind. Keep yourself safe while working with this lumber — and dispose of all debris with care!