Rot Doctor


Subject: extensive wood rot around base of sliding glass door
Date: Sun, 06 Sep 1998

Dear Dr. Rot:
We have just discovered extensive wood rot under the base of our sliding glass door. This door opens onto a small, uncovered deck. The house is off-grade. We have removed the deck & surrounding siding and have determined that it will be necessary to replace the 16ft 2x8 which sits on its edge and runs lengthwise under the door frame and rests on top of another 2x8 (flat and anchor-screwed to the cinder block foundation). The upper corners of the floor joists (which run perpendicular to the soon-to-be-replaced 2x8), just underneath the plywood subfloor, are completely gone. The plywood subfloor is in bad shape for about 8–10 inches from underneath the metallic door frame and back. The interior flooring inside this doorway is tongue-and-groove, 1/2 inch thick, oak. We would like to avoid having to tear up this flooring!!

Right now our game plan is:

  1. Remove the glass door and the 2x8 which runs lengthwise under it.
  2. Dig out the fragments of plywood subfloor until we reach solid plywood (say 10 inches inward). This will leave a (plywood-thick? maybe larger?) gap between the oak floor and the floor joists.
  3. Dig out the fragments of the upper joist corners.
  4. Apply Dr. Rot’s recommended CPES* treatment everywhere in sight.
  5. Try to replace the plywood? This is the tricky part - don’t know how we’re going to do it yet.
  6. Attach new 2x8 planks to either side of damaged joists to help provide the missing upper corner areas. Possibly fill in the resulting gap with Dr. Rot’s recommended filler.
  7. Replace 2x4 studs running up along sides of door frame/jamb - the bottom ends of these are also in bad shape.
  8. Replace 16ft 2x8 plank running edgewise under door frame, attached to joists and sitting edgewise on the anchor-plate 2x8.
  9. Fill in any crevice we can get to with Dr. Rot’s filler*.
  10. Replace door and siding and trim work.
  11. Replace deck.

1. Can you offer any suggestions on this plan?

There is a lot of detail here that is hard to picture, especially when dealing with wood rot, which, as you know, is highly variable. One thing I can say, however, is that if the rotted wood is dry, or can be made dry, then it is a perfect recipient for the Clear Penetrating Epoxy Sealer (CPES*). It may take 2 coats, but once cured the rotted wood becomes harder than new wood. You might keep this in mind re the plywood and stud ends. We also often use the L&L Resin* on top of the CPES*-soaked wood as a filler. it cures in 24 hours and is also very hard, it and the CPES* bond together.

2. We are considering treating the entire area, before we get started, with a copper-based, liquid fungus killer/sealer which we found at our local paint store. Will this hamper the effectiveness of the CPES* and/or filler? And, is this necessary?

These fungicides are usually petro-based and will therefore interfere with the absorption of the CPES*. Our suggestion would be to do all your CPES*/Resin/Filler repairs first, and then go back with the fungus liquid as a final protectant over untreated wood. Any wood that is saturated with the CPES* is very resistant to rot fungi.

3. Which of your products will help us in our endeavor?

The CPES*, perhaps the Layup & Laminating Resin*, and certainly the Epoxy Filler*. Depends on what you’re looking at. New wood should be treated with the CPES* after cutting to size and before installation, especially the ends. This will help protect it from future rot problems. A little CPES* goes a long way on new wood, so the expense isn’t outrageous. All cracks and crevices should also be coated with the CPES*, and, as you suggest, filled with the filler if possible.

Thank You,
Jennifer & Paul G.

You plan sounds well thought through and comprehensive. Replacing the plywood strip can perhaps be done with new wood and our Epoxy adhesive, which is very strong. When cured, all of our products are stronger than the wood they replace.

If you have more questions, please get back to us. We want to be as helpful as we can.


* These products are no longer available, we are offering comparable products. Contact us with any questions.



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