The following article was published by the Professional Pest Manager magazine in their August-September 2014 edition. It was the followup article/conclusion to the June-July 2014 edition.
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The prevention of wood rot falls into 2 categories, moisture barriers and timber preservatives. Moisture barriers can be any membrane like material that physically limits or stops moisture ingress. The most common forms of barriers are surface coatings such as paints, varnishes or specialised synthetic membranes. While these are usually brilliant in preventing moisture uptake, they do have a potential downside. If they begin to fail, the moisture can become trapped behind the barrier.