You can stain pressure-treated wood as soon as it is dry enough to absorb water. New treated lumber is often still wet from the treatment, so stain would not soak in. Depending on the weather and the wood, that can take anything from a few days to a few weeks: Thompson’s and Culpeper Wood both point to about 30 days, and YellaWood recommends staining within six weeks of building. Lumber stamped KDAT (kiln-dried after treatment) can be stained right away. The quick way to decide is the water test below.
Ready to buy stain? The deck stain calculator and fence stain calculator work out how many gallons you need.
What the manufacturers say
| Source | Guidance for new pressure-treated wood |
|---|---|
| YellaWood (treated lumber brand) | Ideally stain within six weeks after construction; the older advice to wait 6 to 12 months no longer applies |
| Culpeper Wood Preservers | Could be ready to seal within 30 days of completion |
| Thompson’s WaterSeal Semi-Transparent | Allow 30 days before applying on new pressure-treated lumber |
| University of Missouri Extension (citing the USDA Forest Products Laboratory) | ACQ- or CCA-treated wood can be finished right after installation, assuming the wood is dry |
| Cabot Solid Color Decking Stain data sheet | Wood moisture content below 15%, or at least 3 to 5 days of dry weather |
| YellaWood, KDAT lumber | Can be painted, stained or sealed immediately |
The water test
- Pick a few spots on different boards, including the ones in shade.
- Sprinkle a little water on the surface.
- If it soaks in and darkens the wood, the wood is ready. If it beads up, wait a few more days and test again.
Sources disagree on how fast the water has to soak in: Thompson’s says within five seconds, while Home Depot’s guide allows up to 10 minutes. Sherwin-Williams simply says the wood is ready if the droplets sink in. If the result is borderline, waiting a few more dry days does no harm.
Weather for staining
- Air and surface temperature at least 50°F while you stain and for the following 48 hours (Thompson’s and Cabot).
- No rain forecast for at least 24 hours.
- Avoid hot surfaces and direct midday sun, which make stain dry too fast and lap marks show. Morning or late afternoon is easier.
- Allow 24 to 48 hours of drying before heavy use, as Sherwin-Williams suggests for decks; check your product label.
What KDAT means
Most pressure-treated lumber is treated with a water-based preservative and sold wet. KDAT lumber is kiln-dried after the treatment, so it is already dry and ready to finish. It is usually marked on the end tag or stamp; ask the lumberyard if you are unsure.
Before you stain
- Clean off dirt, mildew and sawdust; a deck cleaner and a scrub brush work well on new and old wood.
- Let the wood dry again after cleaning before you stain.
- Test the stain color on an offcut or a hidden board, since treated wood often has a green or brown tint.
- Rough-sawn fence boards soak up more stain than smooth deck boards, so buy accordingly.
Frequently asked questions
Is waiting six months still necessary?
No. YellaWood says the 6 to 12 month advice no longer applies to its products, and the University of Missouri Extension calls it a myth for ACQ- and CCA-treated wood. Wait for dryness instead.
Can I paint pressure-treated wood?
Yes, once it is dry. The same water test applies; use a primer and paint made for exterior wood.
Does the same apply to fences?
Yes. Fence boards dry faster in sun and wind than deck boards in shade, so test several areas.
See also deck board spacing, since treated boards shrink as they dry.
Sources
- YellaWood: Staining Pressure Treated Wood (timing and the water test)
- YellaWood: What Is KDAT? (kiln-dried after treatment lumber)
- Culpeper Wood Preservers: Sealing, Painting and Staining (ready to seal within about 30 days)
- Thompson’s WaterSeal Semi-Transparent Wood Sealer (30 days on new pressure-treated wood, water test, temperature and rain)
- University of Missouri Extension: Painting ACQ- or CCA-Treated Lumber (treated wood can be finished once it is dry)
- Cabot Solid Color Oil Decking Stain technical data sheet (moisture content, temperature and weather limits)
- Sherwin-Williams: Applying Deck Stain (water droplet test, sun and dry time)
