Do You Have To Treat Exterior Grade Lumber Or Wood?


As long as there’s a good chance that moisture can reach the wood, it should be pressure treated. This is why the International Building Code requires that siding and structural lumber used for the last six inches of the structure above the ground is pressure treated.


Pressure-treated wood is required whenever you attach framing lumber or furring strips directly to concrete or other exterior masonry walls below grade. Note that this requirement is only for exterior walls, as these may wick moisture onto the lumber.

Can you use Treated Wood with Aluminum? GAME CHANGING ANSWER!!!! pt. 5, Jon to bass boat build

Frequently Asked Questions

Can untreated lumber be used outside?

The only way to properly use untreated wood of any type outside is with the addition of water-repellent preservatives, sealer or paint that contain UV protection. Over-the-counter wood preservatives are available in clear versions, or with stain containing pigment or dye to color the wood.

Does outdoor lumber need to be pressure-treated?

But building code dictates where you can use treated wood in applications — usually where there is risk of excessive moisture. Generally speaking, any wood used in outdoor projects should be pressure-treated. Wood details in your interior design (like cabinetry or furniture) do not need the same level of treatment.

Can any wood be treated for outdoor use?

Planning an outdoor project In general, any wood will work for an outdoor project if it's kept dry and regularly maintained However, some woods do have a higher resistance to decay than others.

How long can untreated wood last outside?

Weather mixed with direct sunlight can damage wood quickly and if left untreated it can happen in a matter of weeks. Untreated wood can last anywhere from a couple of months to over two years.

What can you use treated wood for outside?

Treated wood — wood that’s been infused with chemicals to fend off decay and destructive bugs — is a fundamental construction material for wooden outdoor projects such as decks, arbors and benches. In addition, treated wood is used for siding, wood shingles and trim.

What's the difference between treated and untreated wood?

Treated wood — also known as pressure-treated wood or PT — is widely available to consumers for home and garden projects. You can find treated lumber, plywood, lap siding and even specialty items like lattice and pre-cut stair parts.

When do you use treated wood for siding?

In addition, treated wood is used for siding, wood shingles and trim. Treated wood has been around since the ancient Romans brushed olive oil on structural bridge supports to ward off moisture. A more well-known example is 19th-century railroad builders who soaked wooden railroad ties in smelly creosote to prevent rot.

Is it safe to use pressure treated wood?

Pressure treated timber is affordable, especially if you compare it with other wood types such as redwood. These woods contain chemical compounds that are not entirely safe for human use and need careful handling.

Add a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.