How to Acclimate Decking Boards Before Installation
This step might feel like waiting around, but it's one of the most important things you can do to prevent warping, cupping, and gaps in your finished deck. Take the time to let your boards adjust to your local climate.
Quick Summary
3-7 days
Easy
$0 (just patience)
Why Acclimation Matters
Wood is a living material that constantly absorbs and releases moisture. When decking boards arrive from the lumberyard or home center, they're often at a different moisture content than your local environment. Installing them immediately means they'll change shape as they adjust—and that change happens after they're screwed down.
The results aren't pretty: boards that were tight together develop gaps as they shrink. Boards that were properly spaced buckle and cup as they absorb moisture. Fasteners pull through or pop out as wood moves around them.
Acclimation gives boards time to reach equilibrium with local humidity levels before installation. This means less movement after installation and a deck that looks great for years.
Materials You'll Need
- Sticker boards – 3/4" thick lumber strips to create air gaps between board layers
- Concrete blocks or 4x4 lumber – To raise the stack off the ground
- Waterproof tarp – Large enough to cover the stack with overhang
- Moisture meter (optional) – For precise moisture content readings ($20-50)
Step-by-Step Acclimation Process
Step 1: Choose the Right Location
Find a spot near your deck site that's:
- Level and stable (not on a slope where boards could shift)
- Out of direct sunlight (UV and heat cause uneven drying)
- Well-ventilated (not in a closed garage or shed)
- Protected from sprinklers and ground moisture
Step 2: Create an Elevated Base
Never store lumber directly on the ground. Ground contact leads to moisture absorption, staining, and potential decay.
- Place concrete blocks or pressure-treated 4x4s every 4 feet
- Ensure the base is level so boards don't sag or bow
- Keep boards at least 4 inches off the ground for airflow
Step 3: Stack Boards with Spacers
This is the key to proper acclimation. Air must circulate around all surfaces of every board.
- 1.Lay the first layer of decking boards across your base supports
- 2.Place sticker boards (3/4" strips) perpendicular to decking, directly above each support
- 3.Add the next layer of decking on top of the stickers
- 4.Repeat until all boards are stacked—keep stickers aligned vertically
Pro Tip: Use dry stickers from the same lumber species if possible. Wet stickers can leave marks on your decking. Some builders use paint sticks or plastic spacers to avoid any potential staining.
Step 4: Protect from Weather
Covering the stack seems counterintuitive—don't you want air to reach the boards? Yes, but you also need to protect from rain.
- Drape a tarp over the top of the stack only
- Leave all four sides open for air circulation
- Extend the tarp beyond the edges to shed rain away from boards
- Weight down the tarp corners so wind doesn't blow it off
Avoid This Mistake: Don't wrap the entire stack in plastic. This traps moisture and can cause mold, mildew, and uneven drying. The goal is protection from rain while allowing airflow.
Step 5: Wait for Acclimation
Now the hard part—waiting. The acclimation time depends on several factors:
| Condition | Recommended Time |
|---|---|
| Dry climate, kiln-dried boards | 3-5 days minimum |
| Moderate climate | 5-7 days |
| Humid climate or wet season | 7-14 days |
| Pressure-treated lumber (often very wet) | 2-4 weeks ideal |
Special Considerations by Material
Pressure-Treated Lumber
PT lumber often arrives soaking wet from the treatment process. Moisture content can be 50% or higher. Ideally, let it dry for 2-4 weeks before installation—or at minimum, until a moisture meter reads below 19%. Installing wet PT lumber almost guarantees shrinkage gaps.
Cedar and Redwood
These naturally resistant woods are often kiln-dried and may need less acclimation time (3-5 days). However, they're also more prone to cupping and warping if moisture content is uneven. Stack carefully with consistent support.
Composite Decking
Composite doesn't absorb moisture like wood, but it expands and contracts with temperature. Store in the shade and allow 24-48 hours for boards to reach ambient temperature before installation. Hot boards installed on a cold day will contract and create gaps.
Tropical Hardwoods (Ipe, Cumaru, etc.)
Hardwoods are dense and acclimate slowly. Allow a full week minimum, longer if possible. These woods are expensive—take the time to do it right. Store flat to prevent bowing.
Using a Moisture Meter
A moisture meter takes the guesswork out of acclimation. For $20-50, you can know exactly when boards are ready.
- Target moisture content: 12-15% for most climates
- Dry climates: Target 9-12%
- Humid climates: Target 14-18%
- Testing method: Check the center of several boards, not just the ends
Pro Tip: Test boards from different parts of the stack—top, middle, and bottom. If readings vary widely, continue acclimating until they're consistent.
Common Acclimation Mistakes
Storing boards on the ground
Ground contact causes moisture absorption from below, leading to uneven drying and potential staining or decay.
Wrapping tightly in plastic
Trapped moisture causes mold, mildew, and prevents proper drying. Cover the top only, leave sides open.
Stacking without spacers
Boards touching each other can't dry evenly. Moisture gets trapped between surfaces, causing staining and uneven acclimation.
Storing in direct sunlight
UV exposure and uneven heating cause the top of the stack to dry faster than the bottom, leading to warping.
Being impatient
Three days feels long when you're eager to build, but fixing gaps and warps later takes far more time and money.
FAQ
How long should decking boards acclimate?
Decking boards should acclimate for 3-7 days minimum. In humid climates or during rainy seasons, extend to 7-14 days. For pressure-treated lumber that arrives very wet, 2-4 weeks is ideal. Use a moisture meter to verify boards have reached 12-15% moisture content.
Do composite decking boards need to acclimate?
Yes, composite decking should acclimate for 24-48 hours. While composite doesn't absorb moisture like wood, it expands and contracts with temperature changes. Allow boards to reach ambient temperature before installation to prevent gaps from thermal movement.
What happens if you don't acclimate decking boards?
Skipping acclimation leads to warping, cupping, twisting, and gaps after installation. Wet boards shrink as they dry, creating unsightly gaps. Dry boards absorb moisture and expand, causing buckling. These problems are difficult and expensive to fix once boards are installed.
How do I know when boards are properly acclimated?
The best method is using a moisture meter to verify 12-15% moisture content. Without a meter, wait the full 7 days and check that boards feel dry and match the feel of wood that's been exposed to local conditions. Boards should not feel cooler or damper than surrounding wood.