Rot Doctor


Subject: Help (rot in skylight)
Date: Mon, 18 Oct 1999

Dear Dr. Rot

We have a house in a mountain community in Southern California. The house has a sun room with a large, multi-window skylight with vertical windows in the wall below. I noticed one of the external boards between the windows in the wall under the skylight had some dry rot when I was painting. I removed the board and found what looks to me to be extensive dry rot. The dry rot seems to have attacked the upright wooden member (post) which supports the overhead skylight beam (that is, the roof beam). I pushed a small screw driver about 2″ into the upright beam. I don’t know how wide spread the dry rot is, I didn’t remove any siding to trace where it may have radiated.

I have contacted several local contractors and have spoken to one. He didn’t seem to have any solution other than to remove the siding, beam and paneling inside the house. A very expensive proposition. I got on the Internet and located your site which offers other solutions.

My questions to you are:
Is there an expert in using your products in the Lake Arrowhead area? Perhaps a contractor to whom you have sold your product’s? Lake Arrowhead is in the mountains about 20 miles from the City of San Bernardino.

On the surface (that is, without seeing the extent of the damage that’s visible), is the contractor I spoke to giving me good advice that the only practical solution is to remove the siding and inside paneling to trace the extent of the dry rot? Is he correct about removing and replacing the upright beam (and any other wooden pieces which have dry rot damage) rather than using a product such as yours to kill the dry rot and repair the damage? Should I have someone familiar with your products look at what is visible before I commit to having a side of the house torn off?

We wish to have the needed work done before the winter weather sets in, so a prompt reply would be greatly appreciated.

Many thanks for your help,
Don S.


Your solution here will depend entirely how far you want to go — and how much money you want to spend. The contractor is correct when he says that the only SURE way to know what is happening is to tear things apart and look and see — and then replace. That’s the business contractors are in.

I have an analogous situation. Yesterday I was cleaning out the deck seams on our 50′ tug, preparing to re-seal them from winter rains, which are not far off now here in Seattle. In cleaning one particular seam I hit soft wood…and then more soft wood…and MORE soft wood. As it turned out a portion of the deck was rotten all the way through and I could actually see through to the hull beams below. Discouraging, because what was going to me a minor repair is now going to be a spring project. Any shipwright (the boating equivalent to a contractor) would tell me we have to tear the hull apart now to see just how far the rot has gone. Sure…good solution if I had an immediate $20,000 to spend. So what will I do? I will saturate the hull beams I can see through the opening and all the rotted wood immediately visible with CPES (Clear Penetrating Epoxy Sealer), tape the hole closed and seal it for the winter, and then start my own repairs in the spring. What I do then will depend on what I find when I start tearing away whatever bad wood that remains, but it will involve more CPES saturation, Layup & Laminating Resin infusion, and final filling with some new wood but lots of Epoxy Filler, I’m sure.

The reason for the CPES saturation is that CPES is a very thin liquid that will follow the same paths through the wood that the water followed, and wherever it finds bad wood it will penetrate, stop the activity of the rot fungi, and harden the bad wood. In my case this in itself will not be enough, which is why I will return with the thicker, stronger Layup & Laminating Resin and Epoxy Filler. So right now I will spend a few dollars to halt the problem, benefit the wood to some unknown extent, and give myself the time I need to evaluate it more properly next year when the weather gets better.

And this is pretty much where you are right now. No matter what you do in the future you need to do whatever you can right now to stop the rotting process. Later — if necessary — you can tear away siding and look, if that is necessary. You will also be restoring strength to the deteriorated wood. The application of CPES to any visible rotted wood will allow the product — as on my boat — to follow the same paths as the water did and in the process greatly reduce or eliminate entirely the rotting process.

CPES is applied in these situations in generous quantities and allowed to flood down into the base structures of the building. Where it finds soft wood it will penetrate, and travel very long distances even though the application point is far away. We’ve seen on rotted beams CPES easily travel 15″ through the interior of the beam. So what you would do is flood all visible rotted areas with CPES, applying it until the wood will absorb no more, and then wait for about a week before going back and filling with the Epoxy Filler where necessary before re-painting. CPES treated wood is easily repainted, and in fact the paint will bond better than it will with any other base coat that we know of.

We do work with contractors, but do not recommend them. This is not the kind of work that is popular with contractors because it’s strictly labor — no materials and therefore reduced profits. But you can specify exactly what you want done, i.e., remove the paint, saturate with CPES, fill if necessary with Epoxy Filler, and re-paint.

In the long term it’s difficult to predict what the results will be. Certainly the rotting process will be greatly reduced, if not stopped altogether. It may be all that is needed. One does this and then keeps a sharp eye to see if additional signs of wood deterioration appear, and if they do then they are treated as well. This is exactly the process the State of California uses when they apply CPES to the San Juan Baptista Mission and the Hearst Castle. CPES is also used by the US Navy in the South Pacific Islands, as well as locally, most recently here in Seattle on some old housing.

We would be happy to work with you or any contractor you select to help solve your problem. Our products are available directly through is and we ship every day via UPS GroundTrac. San Bernardino area is about 3 days shipping time from Seattle.

Come back if we can be of further help.