As you shop around for framing options, you probably have noticed that most dimensional lumber comes in regular and pressure treated. Pressure-treated wood comes advertised as the more rot-resistant, insect-resistant, and long-lasting version, so you are wondering if you can use pressure-treated wood for framing. Well, we have done our research and thoroughly answer that question here.
You can use pressure-treated wood for framing. However, pressure-treated lumber costs much more and does include potentially toxic chemicals. Thus, pressure-treated wood is only recommended for outdoor applications and where framing touches the foundation. Further, since house framing in most other applications runs a very low risk of getting wet, pressure treatment is unneeded.
Keep reading the rest of this post for a detailed run-down of the above answer. We also explore the controversial issues of whether there are negative impacts of using pressure-treated wood indoors. Finally, we conclude with the answers to several related questions.
What is the best application for pressure-treated wood?
Pressure-treated wood is required for many framing applications. Specifically, most building codes require pressure-treated wood for any framing that is touching the foundation. This is because this wood might wick up water from the concrete and eventually rot. By using pressure-treated wood instead, the longevity and stability of the home are preserved.
In the same sense, any framing that might get wet would gain a longer life with pressure-treated wood. This includes outdoor awnings, decks, sheds, barns, and other outdoor projects. Pressure-treated wood, while more expensive, has a much longer life when exposed to the elements.
Be careful; building codes vary from municipality to municipality. This means that the required and possible uses for pressure-treated wood also vary. Be sure to check with a local building enforcement officer, contractor, or architect to ensure you follow local guidelines.
One of the most common applications for pressure-treated wood is outdoor decks. Read these great articles to learn more about deck-building, "8 Deck Skirting Ideas To Consider," and "How Often Should You Stain The Deck?"
What makes pressure-treated wood pressure-treated?
Pressure treatment takes regular lumber and pressure to force chemicals into the wood. This process does change the makeup of the wood and gives it a dark brownish/greenish color. Back in the 1940s, pressure-treated wood included chemicals shown to cause harm to humans. However, modern pressure-treated wood uses borates and other milder chemicals, so it is not nearly as dangerous.
The chemicals used in pressure-treated wood provide rot resistance and insect resistance. The chemicals make it difficult for funguses like mold/mildew and bacteria to eat away the wood and make the wood distasteful to insects. These harmful microorganisms are present in almost all moist dirty environments. This means that pressure treatment is a great way to keep wood lasting longer that might get wet.
Can you use pressure-treated wood for interior framing?
According to common understanding, you can use modern pressure-treated wood indoors. However, cleaning all sawdust and debris is highly recommended before the home can be occupied. Further, when working with pressure-treated wood wear a respirator to avoid breathing in harmful sawdust.
Generally speaking, and from a practical perspective, working with pressure-treated wood is no different than working with non-treated lumber. Pressure treatment does add weight to the wood so expect to add a little more work to a home framed with pressure-treated lumber. However, the strength and support capabilities are the same for pressure-treated wood and non-treated wood.
However, a debate exists as to whether pressure-treated wood is safe for indoor use. Some carpenters and designers worry that pressure-treated wood will leach harmful chemicals into the home. However, according to the Environmental Protection Agency (EPA), there is a wide range of toxicity depending on the type of pressure-treated wood. Take note, all sources recommend against using pressure-treated wood for cutting boards and countertops.
Finally, interior framing should never get wet. The siding, sheeting, roofing, and more all protect that from happening. Therefore, the rot-resistance quality of pressure-treated wood serves no purpose indoors. All told, it is possible to use pressure-treated wood indoors. However, the minor added benefits and potential risks are generally not worth the large increased cost.
Can you use pressure-treated wood for floor joists?
Floor joists, like other interior framings, are a potential application for pressure-treated wood. Floor joists made of pressure-treated wood do have a theoretically longer life span. However, pressure-treatment on most floor joists serves no purpose, as those floor joists do not get wet.
However, the situation changes slightly for floor joists on the bottom floor of a home next to a crawl space. Of all the interior framing areas, this calls most for pressure-treated wood. Crawl spaces are usually open to the ground and can get very wet seasonally. Therefore, the space of air in your crawl space is all that separates your framing from the wet moist soil.
Despite the above arguments, non-treated wood still lasts hundreds of years as floor joists above a crawl. This is because the water needs a direct way to reach the wood. Generally, the increased local humidity alone in a crawl space is not enough to cause significant rot of floor joists.
Can I attach drywall to pressure-treated wood?
Yes, attach drywall to pressure-treated wood in the same way you attach drywall to untreated lumber. Using drywall screws or drywall nails, affix the drywall to the framing with a schedule of a nail or screw every 12-inches to 16-inches. Just like with typical applications, be careful as drywall can be very heavy.
Why can't you use pressure-treated wood inside?
As discussed in this post, you can use pressure-treated wood inside. However, regulatory agencies recommend against using pressure-treated wood for some situations like cutting boards and countertops. Generally, people fear using pressure-treated wood indoors because they worry about the chemicals leaching into the environment and causing health problems.
Another worry sometimes mentioned is that pressure-treated wood is more flammable than non-treated lumber. However, there is no evidence that pressure-treated wood will burst into flames any faster than normal lumber. That being said, if pressure-treated wood does burn, it is very harmful to inhale the smoke.
In this post, we answer the question of whether you can use pressure-treated wood for framing. We discussed the pros and cons of using pressure-treated wood both outdoors and indoors. Further, we answered several related questions. Thank you for reading!