Ground-contact vs. above-ground ratings
Treated lumber is sold with use ratings. Ground-contact lumber has higher preservative retention and should be used for posts and for framing that is near the ground, hard to replace, or likely to stay wet.
Check the end tag on treated lumber for its use category. Many builders use ground-contact rated material for all deck framing because joists and beams on decks are difficult to replace and often stay damp.
Fasteners and connectors
Modern wood preservatives can be corrosive to ordinary steel. Use hot-dip galvanized or stainless steel fasteners and connectors rated for treated lumber, as specified by the connector and lumber manufacturers.
How long does a pressure-treated deck last?
Lifespan varies widely with climate, construction and maintenance. Decks that are well built, kept clean and resealed on schedule last far longer than neglected ones.
Rot typically starts where water is trapped — board seams over joists, post bases and the ledger. Good details and maintenance matter more than the lumber alone.
Does lumber grade matter for decking?
Higher grades have fewer knots and defects, so they warp and check less and look better. Premium decking boards (often with rounded edges) cost more but make a noticeably better surface.
What's the maintenance schedule for a treated deck?
- Sweep regularly and clear gaps.
- Clean each spring.
- Water-test and reseal or restain when water soaks in.
- Reset popped fasteners and replace split boards.
- Inspect framing, ledger and railings annually.
Why is treated wood used for deck framing even under composite?
It's strong, economical, widely available and resistant to rot and insects. Ground-contact rated material is often used for framing because it's hard to replace and stays damp.
How does pressure-treated wood differ across the states we serve?
Treated wood's upkeep depends on moisture exposure. The figure varies most between Washington (95) and Minnesota (60).
| State | Wet days / yr (median) | What it means |
|---|---|---|
| Georgia | 80 | Frequent rain: flashing, drainage and airflow protect pressure-treated wood |
| Illinois | 74 | Drier spells: sun and checking are as important as moisture for pressure-treated wood |
| Kansas | 60 | Drier spells: sun and checking are as important as moisture for pressure-treated wood |
| Maryland | 81 | Frequent rain: flashing, drainage and airflow protect pressure-treated wood |
| Massachusetts | 82 | Frequent rain: flashing, drainage and airflow protect pressure-treated wood |
| Minnesota | 60 | Drier spells: sun and checking are as important as moisture for pressure-treated wood |
| North Carolina | 75 | Drier spells: sun and checking are as important as moisture for pressure-treated wood |
| Pennsylvania | 79 | Drier spells: sun and checking are as important as moisture for pressure-treated wood |
| Tennessee | 84 | Frequent rain: flashing, drainage and airflow protect pressure-treated wood |
| Virginia | 77 | Drier spells: sun and checking are as important as moisture for pressure-treated wood |
| Washington | 95 | Frequent rain: flashing, drainage and airflow protect pressure-treated wood |
Figures are medians across our covered communities in each state, from NOAA 1991–2020 climate normals and the Census Bureau's 2020–2024 American Community Survey. Each state and community page explains local conditions in more detail.