Do Cedar Fence Boards Shrink or Expand?


Cedarwood is one of the more popular materials for fencing. Actually, it is known for being one of the most sturdy and durable woods on the market. Although when it comes to fencing, it’s known to shrink a month after installation.

Cedarwood expands slightly when it absorbs moisture and then shrinks in warmer conditions. Because of this, cedar fence boards are known for shrinking as much as 1/4″ per board in warmer conditions, leaving gaps in the fencing over time.

Why Do Cedar Boards Shrink and Expand?

Wood is known to gain or lose about 1% of its moisture content for every 5% change in humidity.

This means that wood is at its largest in the winter months, and it’s smallest, and most shrunken, in the summertime months when moisture is absorbed by the heat of the sun.

Cedarwood, specifically, consists of two separate layers. The outer layer soaks up moisture quickly, but also expels moisture quickly, meaning that in the summer months the exterior of cedar can feel dry to the touch.

All new wood fences, including cedar fences, will have shrinkage, leading to gaps in your fence!

This can be misleading to someone who doesn’t know a lot about the absorption of water by wood.

The inner layer of Cedar is known to absorb moisture as well, but expel it at a much, much slower rate, meaning that the shrinking of the inner layer of the wood happens over a longer amount of time. Many fences are made out of cedar for this reason.

Because the rate of shrinkage is slower, this can lead people into believing that their wood will continue to be a specific size. But but over time, it will drastically change.

This is generally true where cedar fencing is placed above the ground, where it is subject to conditions such as rain or snow.

Underground portions of a cedar fence run the risk of further damage through the soaking up of water from the ground.

This is why it is important to take precautionary measures for the ends of your cedar board. It’s not too difficult really.

You can do this by soaking the ends of your boards and posts in copper naphthenates, such as Nasco or Copper Green Wood Preservative. This will help the ends of the boards that are stuck in the ground to last as long the portions that are above ground.

How to Take Shrinkage into Account when Building a Cedar Fence

Cedar is a high-quality wood that is a fantastic material to build fences with, but it is important to do your research when it comes to building with cedar.

Since it is prone to shrinkage, especially in warmer climates or seasons, there are a few precautions to take before building a fence made of cedar.

  1. Dry it out!
  2. Measure its moisture content beforehand.
  3. Place boards as close together as possible.
  4. Use a Stain

1. Dry It Out!

The best thing to do before building a fence made of cedar is to dry it out. Depending on where you live and the moisture content of your specific climate, drying out cedar can take different amounts of time, specifically, from around 3-12 months, depending on how dry your climate is.

If you have access to a heated, dried out atmosphere such as a kiln, this wait time can be drastically reduced to as much as 10 hours.

2. Measure Moisture Content

Whether you dry out your boards first or not, it’s good to know the boards moisture content before you put them. Then you can anticipate the amount of shrinking that will occur.

It’s extremely easy to measure the moisture content of your cedar with the use of a moisture gauge. The recommended amount of moisture is under 20% moisture, so around 12-15% moisture.

3. Place Boards as Close Together as Possible

Line your cedar boards as close as they will go. Although cedar swell with moisture, your boards will shrink more than the will expand.

Shrinking will happen over time, but to reduce your gaps and to ensure that the gaps in your fence are even, place your boards as close together as possible.

Keeping these things in mind while you build will help to make sure that fence posts will continue to be as close together as possible, leaving you with a sturdy, well-built fence that looks professionally cut and built.

4. Use a Stain

Using a protective stain to keep moisture or heat from getting in may help.

Since cedar is a softwood, it’s best to use a deep penetrating oil-based stain that is thin in terms of viscosity.

Can You Fix Cedar Fence Shrinkage?

Cedar shrinkage can’t really be fixed but some preventative measures can reduce the shrinking. Wood can be temperamental and without proper premaintenance, can lead to the wood doing whatever it wants to.

Depending on what type of moisture content your area has, wood can expand and shrink at an alarming rate.

Why It’s Important to Place Cedar Boards as Close as Possible

Fence posts made of wood are meant to be placed together with as little space between them as physically possible.

This is especially important when building a fence where the boards are placed on top of one another instead of side by side. The ultimate goal with fences built in the style that Cedar is used for is complete privacy and protection, which is hard to do with gaps.

To know more about spacing, read our article here.

It’s also important to note that cedar, while it is pleasing to the eye and even smells amazing, is prone to what is called checking. Checking is when the exterior layer shrinks faster than the interior layer, causing cracks in the exterior portion of the wood.

Building a fence with dried out wood and placing the boards as close together as possible is the best possible method of making sure that checking doesn’t occur.

Why is Cedar Used Despite its Tendency to Shrink?

Cedar is a rare softwood that can be used for just about any aesthetically pleasing purpose. Among its use as a fencing material, it’s also used for porches, decking, siding and trim because of those same reasons.

Another common use for the cedar is in the interior of the house. Its often used in indoor decor due to the fact that it naturally smells amazing and keeps bugs such as termites at bay, which is important when choosing wood that will exist inside of a house.

For more information on the basics of Cedar and how to protect against unwanted shrinkage, watch the Youtube video linked below:

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