The Rot Doctor


Subject: Exterior Log Repair
Date: Thu, 30 Sep 1999

Dear Doc:

I have two problems with exterior logs. One is how to fill in large cracks that have developed in some of the logs and also small cracks. Even though I have treated the exterior with preservatives, I 'm afraid that they will develop into rot. Second I have a log that has developed I believe, rot inside, even though the exterior of the log is still in place,one can tap the log and it sounds hollow rather than solid. This problem does not affect the entire log (which is about 3 to 4 feet long and approx 8 inches thick) but only about 8-10 inches of it. Any help would be appreciated. These problems only affect the south side of the house.

The cracks and crevices, as you are aware, are potential entry points for water, and water and the right temperature conditions can result in rot. But the solution is fairly simple and shouldn't be that expensive. When the logs are dry you should apply CPES (Clear Penetrating Epoxy Sealer) to the inside and sides of the cracks. It shouldn't take much, and two coatings are recommended. What this will do is eliminate any fungal or bacterial problem, seal the wood against water penetration and eliminate any rot-development problems in that particular area. The CPES can be applied with a brush or syringe -- your choice. If the wood is good and not deteriorated it doesn't take much CPES to accomplish this task.

If the crack absorbs a lot of CPES, then that means that the CPES has found a channel into the interior of the log, where, you can be sure, moisture has also gone. The CPES in this case will follow the same paths the water followed and perform the same protective measures -- eliminate the fungi/bacteria and protect the wood.

Subsequent to the CPES treatment, you can fill the cracks with a mixture of our Layup & Laminating Resin and coarse sawdust if you wish.

CPES treatments into wood interior are permanent. It is just done one time. The epoxy bonds and stays with the wood as long as the wood is there.

The hollow sound you describe is common for logs. The wood has rotted the interior, where environmental conditions are ideal, but not the exterior where the conditions are not to the fungi's liking. For a limited area, such as you describe, the best test is to drill some large holes (3/8" or larger) into the top of the log until you hit the vacant area. See what comes out on the drill, if anything. You'll feel the bit plunge when it hits the open area. You would then saturate the interior by flooding it with CPES (it could take a gallon or more, because the CPES will follow any soft wood it finds inside). Following that you can either leave it alone if you believe the log has sufficient integrity, or you can go back and fill the area with a pourable mix of our Layup & Laminating Resin and coarse sawdust. This will make the area totally rot free and impregnable. The only option here would be to cut the face off the log over the hollow area and treat the interior with CPES, fill with any scrap wood that has been CPES-treated and bonded in place with the L&L Resin/sawdust, and then the log face replaced and bonded into position with the L&L Resin.

I can say honestly that CPES is the only product on the market that can make these kinds of log restorations. You can use borates, but they do not restore any strength to the wood and they leach away over time if any moisture is present. Borates can be useful, but only subsequent to CPES treatment.

I hope this has been helpful, and come back if you have additional questions.