October 13, 2015 | BY: childress_admin

Rotten Logs – The Fungi Beneath

Have you met the secret destroyers of log homes?  We have introduced you to the turbulent termites and the pecking woodpecker, but have you met the log home destroyer who is the ultimate master of disguise? If not, let us introduce you to…fungus!

Fungi are responsible for a majority of rotten logs on log homes.  In favorable environmental conditions, fungi will essentially eat the wood of your home, leading to decay and rot.  Unlike more complex organisms, fungi do not have a digestive tract to breakdown and digest their food.  Therefore, fungi use a straw-like structure called hyphae to release digestive enzymes into their environment that break down wood into a digestible form.  Then the fungi can readily absorb the nutrients from the wood, causing rotten logs.

A close-up image of white fungi with capsule-shaped bodies with white stringy fibers against a wood background.

Fungi are responsible for a majority of rotten logs on log homes.

Fungi can wreak havoc if log home maintenance is neglected.  Let’s look at the conditions that are conducive to wood rot and decay in your log home.

The Perfect Concoction For Log Rot

Fungi are the primary causes of log rot and are introduced to the logs through water or moisture.  Many people erroneously believe that water causes rotting logs, but it is actual its microorganisms that cause the destruction.  Logs burdened with cracks and gaps are susceptible to log rot, as these create entry channels for fungi to get within the wood.  Once the fungus infiltrates the logs, it just requires a few other basic necessities for survival.  These requirements are:

Warm Tempuratures

Microorganisms responsible for log rot thrive in temperatures greater than 60 degrees.  Therefore, you may notice wood rot in the warmer months.

A close-up image of brown rotting wood with many cracks and crevices.

Fungi eat cellulose and lignin, which are the carbohydrates found in wood.


According to the United State Department of Agriculture (USDA), fungi thrive in environments with at least 20% moisture.  This is higher than the recommended moisture content of logs in log homes.


Fungi are aerobic organisms, which means they require oxygen to function.  This key ingredient is needed for the fungi to begin the process of log decomposition.


Fungi enjoy eating cellulose and lignin, which are the carbohydrates found in logs.  So let’s face it, your log home is like an all-you-can buffet.  As fungi gorge on your log home to satisfy nutritional needs, the logs become damaged and rot sets in.

Prevention is the Best Medicine

Taking measures to prevent log rot means eliminating environmental factors that support fungi growth—most importantly moisture.  Here are a few tips for reducing moisture exposure to your log home:

  • Clear Gutters—Ensure that gutters and downspouts are free of debris.   Proper water drainage is key to reducing moisture accumulation, which is a breeding ground for log rot. Check out Lowe’s Home Improvement YouTube video on How to Clean Rain Gutter and Downspouts.
  • Eliminate Standing Water Near Log Homes— Prevent drained water from sitting near your foundation and eliminate wood to soil contact.  Logs should be at least 2 feet away from the soil.  Some homeowners implement drainage systems to keep soil dry near the foundation.  Check out this YouTube video: 4 Common Rainwater Drainage Problems and How to Solve Them, Apple Drains, Charlotte NC for a review of different drainage systems.
  • Maintain Log Stain and Topcoat—Protect your logs by keeping your exterior stain and topcoat in good condition.
  • Protect Log Cracks—Apply a sealer to cracks on exterior logs to prevent exposure to moisture.  Pay special attention to the ends of the logs and knots, where cracks are likely to form.    Also look for cracks on the part of the log that faces upward, which can act as a collection bin for rainwater.
  • Maintain Chinking—Moisture can seep through cracks or areas of impaired adhesion in chinking and caulking.
  • Monitor Roof Structure for Impaired Integrity—Make sure shingles, flashings and other roof structures are intact.  Large roof overhangs can help shield the logs below from exposure to precipitation.
  • Fix Plumbing Leaks—An interior pipe burst or other plumbing leaks can also cause log rot.  If you think you may have a plumbing leak, please read WikiHow’s article: How to Find A Water Leak in Your House.

Following these tips and basic log home maintenance will help reduce the occurrence of rotten logs.  If you notice some questionable areas of log rot or think that you have a moisture problem, please give us a call.  It is important to identify a potential problem before it turns catastrophic.

Having performed log home maintenance since 1972, our professionals are skilled at diagnosing log rot and fixing related problems.  We can even help you develop a plan to prevent future log rot.  We would be happy to come out and inspect your home for log rot and offer viable options to remedy the situation.   Remember, don’t wait; contact us today!

Interested in learning more about the different log rots? Stay tune to our next post where we will talk about different log rots and potential solutions!


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