The Rot Doctor


Subject: boric acid preparations
Date: Fri, 03 Jan 2003

Some websites recommend using a boric acid solution to prevent further decay of rotted wood, then applying an epoxy filler. Would you recommend the same - perhaps before using CPES?

I was disappointed to see that your website does not appear to mention boric acid at all. That makes me (and probably others) a bit skeptical about your expertise. You might want to add some discussion, either pro or con, regarding such a widely-known and recommended treatment option.

Thanks for your help.

We are quite familiar with borates around here. You are right, we should probably mention it on our website. I'll put it on the list. Like everything else, borates have their pros and cons. The biggest pro is that it is pretty cheap, and very effective under the right conditions. The biggest con is that outside the right conditions, it's effectiveness drops off considerably. CPES is effective in a much wider set of conditions.

Applied properly, it is a good long term protectant against rot and insect damage. If you have a chronic leak, water can leach the borate out of the wood, removing it's protection. If you keep the wood dry, it really doesn't need protection against rot, so then it's main effectiveness is against insect damage. In a high moisture environment, it is not very effective. If I had an attic, basement, or crawl space, and I was worried about termites or dry rot, borates are good insurance. On the exterior of a structure, they are less effective due to the leaching effect of moisture.

CPES, on the other hand, is not affected by moisture. It can be used in high moisture environments, and will never be leached out of the wood. Practically speaking, it has all the benefits of the borate, except the low price, without any of the drawbacks. So if I am using CPES on an area of rotted wood, there is no need to use borate as well. In short, I see borate as a cheap insurance in a low moisture environment, and CPES as an effective rot or insect damage repair product in low or high moisture environments. You can use CPES as a preventative treatment, but it is somewhat costly when used this way.

Please let me know if I can answer further questions.