Techniques to inhibit wood decay

The new wood most available today for exterior applications is prone to rot from decay fungi.  There are some species not grown in monocultures or force fed with fertilizers that better resist decay. 

I think many of us, especially those only familiar with the common modern day woods, probably believe it is normal and acceptable for wood to first shed its paint, and then begin the decay process within 5-10 years of installation.  After all we may have been taught to simply remove it, replace it with similar wood & techniques, then hope for better results.  This is a cycle that can be stopped. Exterior wood should be designed to last for decades with good preventative maintenance.

Take notice of peeling finishes.  This is often due to water being absorbed into the end grain of permeable wood in vulnerable areas. The fungus spores settle in & begin consuming the wood.  These wood decay fungi need to be controlled by not allowing the wood to stay wet.  This will keep water from penetrating deeply so the wood has a chance to dry out fast.

Specifications to stop this from happening can vary slightly for different species & are especially important in locations where porous end grain is exposed to excess water, such as window trim, jambs, sills etc.  (I won't discuss frame rot now though similar principles apply).  Some simple specs. that will greatly lessen porosity & decay are as follows:

1. Precut the wood pieces, apply liquid borates especially to the end grain, dry below 20% moisture, apply epoxy consolidant 100 to end grain using multiple coats if it absorbs fast, then an option of top coating with epoxy patch to better fill tiny end grain voids.

2. The pieces could then be set aside to cure, or they can be fastened as normal with the wet epoxy patch 200 acting as an adhesive but especially as a sealer for the joint to lower its porosity.   

-Paul Marlowe
ConServ Epoxy LLC Owner

March 08, 2008
Re: Techniques for controlling decay in wood

I agree with Paul.  Back in the early 1980s we began treating the end-grain of exterior wood with epoxy. We did not know if this would have good results, so we did several projects over during the 80s where we applied epoxy to some ends and not to others. Through the 90s we went back to examine the results. These side-by-side comparison field tests proved this is an effective method and we have been using it ever since.
-johnleeke