The Rot Doctor


Subject: question regarding wooden gutters
Date: Thu, 29 Sep 2005


I have about 125 linear feet of Fir wooden gutters that are quite shallow. There are some leaks at the joints and I can definitely see wood deterioration (rot) at places where water standing water has accumulated. There are a few leaks, and these are primarily at the joints. To my knowledge, the gutters have not been treated with linseed oil. If weather is relevant, I live in the Boston area.

From your website I am guessing I need CPES and FILL-IT Epoxy Filler. Could you please confirm this and suggest how much of each I should order. Regarding the CPES application, the rot only appears to be in the bottom channel. Does this mean I would not need to coat the entire channel, and instead just coat the bottom portion? Also, once I have done this, I assume I should apply linseed oil every year, but could you please confirm this.

I can see some tar applications where there are leaks. Should I leave this intact or remove it and apply the Epoxy Filler?

Thanks for your help!

Best regards,

Eugene L.


The CPES is the crucial ingredient in stopping the wood rot, as well as hardening any soft wood. After the CPES has been applied, then just about anything can be used to repair leaks, including tar. You should be aware that CPES will somewhat dissolve tar, so the CPES may turn dark in the areas where it hits the old tar. This does not significantly impair the ability of the CPES to protect the wood.

We would suggest using the Fill-It only to fill any vacant spaces, and use a non-silicone caulk to seal the joints. The best caulk/sealants are the 100% polyurethanes, such as 3M™ 4200 and 3M™ 5200.

We would also suggest coating the inside of the gutter, after the CPES has vented off the carrier solvents (2-3 days, or longer). You can use paint, or perhaps better yet, a tar compound or some other heavy coating, such as our Elastuff 120. This will protect the CPES'd wood from UV light degradation.

It's difficult to predict how much CPES will be required, because so much depends on the absorbency of the wood, and you do want to allow the wood to absorb all that it will. CPES will protect all wood, but to stop the rotting process and harden soft wood it is only necessary to apply to the part of the channel that is deteriorated, as you suggest.

I believe that you will use at least a gallon of CPES on 125 lineal feet, and perhaps more. To get a gallon you would buy two of our 2-quart units of CPES, which will be close to $100.00. For $153.00 you can get our two gallon CPES unit, and I'm fairly certain that this would be sufficient for the gutter treatment. This time of the year in Boston you would want our Cold Weather Formula.

Feel free to come back if you have additional questions. If you wish to order you can do so via phone or our secure on-line order form. Shipping time to Boston from our South Carolina warehouse is three business days.


Note: Current pricing on all our products can be found on the Product Information page.