The Rot Doctor


Subject: CPES for use on LVL's
Date: Friday, July 13, 2007

Hi Doc,

The Engineer for the project has a question about the product. Can you help me answer this?

Based on the Rot Doctor website,, Rot Doctor CPES warm weather-formula seems to appropriate as a protective coat for wood preservation. However, I don't see anything on the website that deals with composite lumber such as the LVL's that I've recommended. I'd like Mark to obtain from Rot Doctor a recommendation for use on LVL's.

I looked at the sample that Mark has on site; it provides a clear finish with a slight sheen, sort of like a coat of poly-urethane.  Any CPES-treated lumber that is to be painted needs an additional primer coat of poly-urethane, according to the web-site.


Shawn B.


Please pass the following to your engineer.

LVL is a type of engineered wood. Similar to plywood. LVL, plywood, MDF, OSB, and regular dimensional lumber are all fine for use with CPES.

If the adhesive in an engineered wood product is susceptible to petroleum based solvents, I would recommend caution in the use of CPES. But to my knowledge, no engineered lumber uses any adhesive/resin that would be a problem. Most use phenolic resins which are fine in conjunction with CPES. In short, CPES and LVL should be fully compatible.

CPES is an excellent primer under paints. And an excellent method for keeping moisture from entering wood exposed to the elements. We feel that keeping moisture out of wood is critical in the long-term life expectancy of wood. CPES is not particularly resistant to UV damage. So if it is used in areas that receive direct sunlight, we recommend over coating with a quality exterior paint, polyurethanes being the most durable.

I hope I have answered your questions sufficiently. Please let me know if you have further questions.