Getting rained on is an inevitable part of leaving firewood outside. But just how much it affects the wood depends on a variety of factors. With some basic preparation and care, a little rain here and there generally won’t cause too many issues.
How rain impacts firewood
Rain can affect firewood in a few key ways:
- It makes the wood wetter. More moisture content means it will burn slower and less efficiently, producing more smoke and creosote.
- It accelerates rot and decay. Extended exposure can cause fungal growth and deterioration.
- It washes away oils and resins. These compounds help the wood burn hotter and faster.
The amount of harm caused depends on the intensity of the rainfall, the length of exposure, and the type of wood. Denser hardwoods like oak can withstand more rain than softer woods like pine.
Best practices for minimizing effects of rain
If you need to keep firewood outside, here are some tips to limit rain damage:
- Stack it under a roof or tarp. Even a basic covering will protect from light-moderate rain.
- Elevate it off the ground. Place on pallets or blocking to prevent water pooling underneath.
- Store bark-side up. Natural bark helps repel water away from the cut ends.
- Angle the stack to promote runoff. Slope it gently to keep the top surface drier.
- Season it fully before rain comes. Well-cured wood withstands moisture better.
- Bring it inside once wet. Let it dry out again before burning.
Drying out wet firewood
If firewood does get soaked, it needs to be dried back out again before burning. Here are a few effective methods:
Let it sit uncovered
Given enough time, wet firewood will dry out on its own if left uncovered in a sunny, windy area. Turning the pieces periodically will help accelerate drying.
Stack and cover
Restacking the wood in a criss-crossed pattern improves airflow. Covering just the top protects from more rain while still allowing ventilation.
Move it indoors
Relocating firewood to a garage, shed, or covered porch gives better control over drying conditions. The warmer and less humid, the better.
Use fans or dehumidifiers
Positioning fans nearby or running a dehumidifier in an enclosed space with wet firewood will actively speed drying by increasing airflow and removing moisture from the air.
How to tell when firewood is dry enough to burn
Look for these signs that soaked firewood has dried sufficiently for burning:
- Checks or cracks form on the ends of logs
- The wood lightens in color
- It feels lighter and loses moisture weight
- The surface is dusty instead of damp
- It sounds hollow when two pieces are knocked together
- The moisture meter reads 20% or less
Dangers of burning wet firewood
It’s important not to burn firewood that is still wet, as this can cause several issues:
- Poor heat output – Wet wood has lower BTUs so doesn’t burn as hot.
- Excess smoke – The extra moisture causes more smoke pollution.
- Increased creosote – Wetter wood leads to more chimney creosote buildup.
- Higher emissions – More moisture means worse emissions and air pollution.
- Foul odors – The smoke smells worse when burning wet wood.
- Greater risk of chimney fire – Creosote buildup heightens the chance of a chimney fire.
Moldy firewood concerns
Extended wetness can also cause firewood to develop surface mold. This is usually just a cosmetic issue that does not affect burn properties. However, those with mold allergies may want to avoid handling moldy wood to prevent reactions. Wearing a mask while moving and stacking moldy firewood can provide protection.
Using wet firewood efficiently
While it’s best to only burn properly seasoned dry wood, you may sometimes be forced to burn wood that is still a bit wet. Here are some tips to use wet firewood effectively:
- Mix it with dry wood – Use wet logs alongside dry wood to help balance out the moisture.
- Split logs – Splitting exposes more surface area to dry out.
- Use smaller pieces – Shorter, narrower pieces will dry faster than large logs.
- Burn hotter – Use lots of kindling and keep the damper wide open for hottest fire.
- Check your chimney – Clear out any creosote before it builds up.
Signs your firewood might be too wet
Look for these clues that your firewood has not fully dried and may be too wet for optimal burning:
- Dark weighty wood with little checking
- Splinters easily when chopped
- Contains shiny patches or beads of water
- Moisture meter reads above 20%
- Hissing or popping sounds while burning
- Produces dense white smoke
- Does not want to catch fire or stay lit
- Sizzles instead of fully burning
How drying firewood changes its weight
Fresh cut green wood can be 50% water by weight. As it seasons, the moisture content drops substantially. Here is how the weight decreases over time:
| Moisture Content | Wet Basis | Dry Basis | Percentage Weight Loss |
|---|---|---|---|
| Green | 50% | 100% | 0% |
| Air Dried (3 months) | 25% | 33% | Up to 33% |
| Well Seasoned (6-12 months) | 20% | 25% | Up to 50% |
| Kiln Dried | 6-8% | 7-8% | Up to 92% |
So firewood at 25% moisture weighs about half as much as when freshly cut due to water loss during drying.
Tips for faster firewood drying
Here are some methods to expedite the firewood drying process when time is limited:
- Cut wood into smaller splits which dry out faster.
- Stack loosely to allow maximum airflow between pieces.
- Elevate wood off damp ground using pallets or blocking.
- Store wood in a sunny location exposed to wind.
- Cover only the top of the stack while leaving the sides uncovered.
- Turn and rotate pieces periodically to expose all sides to air.
- Increase spacing between pieces for improved airflow.
- Move firewood to a warmer, drier location like a covered porch or garage.
- Use electric fans to force airflow through the stack.
- Consider a kiln or solar kiln method to actively dry the wood.
Firewood drying times by wood type
Drying times can vary based on the type of wood. Here are approximate drying times under cover:
| Wood Type | Drying Time |
|---|---|
| Softwoods (pine, fir, spruce) | 3-6 months |
| Hardwoods (oak, maple, ash) | 6-12 months |
| Fruit Woods (apple, cherry, pear) | 9-18 months |
Softwoods generally dry faster because they have less dense grain. Fruit woods are often slower to dry because of their higher densities.
Best moisture content for burning firewood
Firewood burns best – and safest – at a moisture content around 15-20%:
- Below 15% is considered overly dry and may burn too quickly or dangerously.
- 20% is ideal for clean, efficient burning and easy fire starting.
- Above 25% and smoke output, creosote, and inefficiency start to increase.
- Over 30% is generally too wet for proper seasoned firewood.
Test moisture levels with a moisture meter. Well seasoned firewood kept dry will stay in the ideal 15-20% range for burning.
Dangers of burning wet or unseasoned firewood
It’s crucial to burn only seasoned dry firewood. Wet or unseasoned wood leads to:
- Lower heat output – Up to 50% less than seasoned wood.
- Excess smoke and air pollution.
- Increased creosote buildup in chimneys and flues.
- Higher risk of chimney fires from creosote deposits.
- Foul rotten egg odors from smoke.
- Low temperature smoldering fires instead of hot clean burns.
- Faster wood consumption as moisture content requires more heat energy.
Burning wet wood essentially wastes energy as heat is used up drying the wood instead of warming your home. Letting firewood season properly minimizes these issues.
Signs firewood is not seasoned
Look for these signs that firewood has not been adequately seasoned and cured:
- Still feels green, wet, or heavy
- Has not checked or cracked at ends
- Makes a dull thud when pieces are knocked together
- Oozes sap or has wet spots
- Is still easy to chop or split
- Has not noticeably changed color
- Burns poorly with smoky low flames
Well seasoned firewood has the opposite traits – lightweight, cracked ends, hollow knocks, no sap, difficult to split, faded color, and burns cleanly and efficiently.
Conclusion
Getting rained on is usually only a minor setback for properly stacked and covered firewood. Keeping it elevated and under a roof minimizes any impacts. If wood does get soaked, quickly drying it again prevents any rotting or deterioration in quality. Avoid burning firewood that remains wet, and use caution when bringing damp wood indoors to dry. With some basic care before and after rain, firewood can successfully get wet without causing significant problems or reducing its heating value.
