The Rot Doctor


Subject: QUESTION! (gutter repair)
Date: Wed, 03 Oct 2001

I've purchased your product to use on my wood gutters, which are largely in good condition, but for a few spots that have rotted.

I've just spoken to a wood mill company that sells wood gutters, who advised that I should NOT use any type of resin or other rot protective inside the gutters that are not rotted. He advised to only use non-drying oil.

He is not familiar with your particular product, but he thinks anything other than oil will eventually breakdown and allow moisture to collect under the product, which will ultimately cause the wood gutter to fail.

In fact, the only reason I have the rot problem is because the prior home owner, years ago, used copper liners and eventually the moisture collected underneath the copper liner. I'm sure he thought, at the time, he was protecting the gutter. I don't want to make the same sort of error.

What do you advise???

The mill gutter people are partially correct, but not entirely correct. Standard resins, whether they are polyester, acrylic, or epoxy, are thick and quick-setting. When applied to wood they quickly harden and form the same kind of "shield" over the wood that your copper liners formed. Water gets trapped under the "shield", gets warm and wood rot is likely to occur.

The non-drying oils are okay, but they too are subject to biological damage. There are bacteria that thrive on oil-soaked wood and will break it down in a process similar to that of the rot fungi. All it takes is a clog of leaves or other residue to get the wood temperature to the level where the bacteria can flourish.

CPES (Clear Penetrating Epoxy Sealer) is a highly specialized epoxy. It is very thin, like diesel fuel, slow-setting, and deeply penetrating. It does not sit ON the wood, but penetrates INTO the wood and saturates the individual wood fibers with epoxy resin. Once in the wood, the epoxy does not go away, and nothing alive will eat epoxy. Thus, the wood is permanently protected. Paint can be applied over the CPES-treated wood to protect it from UV damage.

You can use the oil, but it is something you will have to re-apply every several years. CPES will last indefinitely.

If you do use oil, DO NOT apply it to any deteriorated wood BEFORE the CPES is applied. The use of the CPES on the deteriorated wood is essential, and the wood should be allowed to absorb all that it will. A few days AFTER the CPES is applied, then you are free to apply oil or paint or just about anything else.

I hope this is helpful. The information above is accurate, and comes from years of experience by us and many, many others in the treatment and prevention of wood rot in the marine industry.