Normally, when people think of decks, they often think about what they can see (deck boards, railings, etc.). However, the most important part of a deck is actually what you can’t see – it’s the framing & substructure.

Deck substructure provides the frame that holds up those beautiful deck boards. It also includes everything beneath like footings, posts, ledger boards and joists to keep your deck stable, strong and safe.

According to,

“For the best (deck joist) results, consider using kiln-dried lumber for the substructure to reduce twisting, warping, sagging…” (

To help you understand just how important the substructure of a deck is, here are some of the most common choices for framing your TimberTech Deck

Most Common? Green/Wet Pressure Treated Lumber for TimberTech® Decks

The most popular deck framing material today is pressure treated lumber. Treated with water and chemicals, pressure treated lumber protects your lasting deck against rot and fungal decay. It’s also a top choice for builders. It provides durability at a low cost. And, it’s readily available at most lumberyards and big box stores. However, that doesn’t mean that green/wet lumber doesn’t have its drawbacks.

Green/Wet pressure treated wood is normally dripping wet with moisture and chemicals. Since it’s filled with moisture, the wood is heavier and harder to work with. And as that moisture leaves the wood during the normal drying process of wood, the joists have a tendency to warp, twist and cup as they lose that moisture. Over time, this can lead to waves in composite deck boards, as well as instability.

Another factor that turns people away from Green/Wet lumber? Unlike Brown KDAT, green lumber has a waiting period of 6-12 months to paint, steal or stain. That simply isn’t necessary with KDAT, as it’s already been dried and can take stain or sealer immediately.

Best & Recommended: KDAT Pressure Treated Lumber for TimberTech® Decks

The best option for affordability, stability and lasting performance is Kiln Dried After Treatment (KDAT). KDAT wood goes through the same process as green/wet wood with one key difference – after the wood is treated, it’s then put in a kiln where most of the moisture is removed from the wood.

When moisture is removed from the wood (as much as 80%), the frame and joists will have less tendency to warp, twist and cup. The result? KDAT provides the added stability not offered by wet/green treated lumber.

If you’d like to use KDAT lumber for your TimberTech Deck Framing, contact the experts at Northern Crossarm Company. Northern Crossarm Company is the largest KDAT Wood Treater in Wisconsin. They have hundreds of stocking dealers East of the Rocky Mountains. To find your nearest dealer location, email or call 715-723-4100.

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