Dry Rot

James Lagergren, Owner, Rainshadow Home Inspection

James Lagergren is the President of Rainshadow Home Inspection and Rainshadow Inspection Services Inc. Services include pre-sale home inspections, new construction walk-throughs, Energy Audits, Blower Door Testing, Infared Thermography, Moisture Evaluations and Inspections on behalf of Insurance Companies or for the purpose of insurance claims. James is an active member of many civic and non-profit groups in Port Townsend, WA and the greater Pacific Northwest.

So your about to buy a house. Let’s say the house is old, in this area old can mean almost anything, from an 1890’s Victorian to a 50’s rambler. Old can simply mean an early 1980’s single level that has had years of deferred maintenance. Perhaps this seems a bit pedantic but the way we use words and the language we communicate with has an effect on what things mean. This post will delve specifically into a phrase that I hear used all the time, from contractors, realtors, potential clients and even other home inspectors, that term is dry rot.

Dry rot in it’s most basic sense that people commonly use it means “rotted wood that isn’t wet anymore”. The problem with using the phrase is that it describes a condition that doesn’t exist. A better way to describe cellulose (wood) that has issues would be to say, “that is sound wood” or “that wood is un-sound”. But the term dry rot continues and so does the misunderstandings associated with calling something what it is not.

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I’m a licensed Structural Pest Inspector in addition to being a licensed Home Inspector. As a part of being a Pest Inspector – I have to correctly identify wood rot by type and all of the conditions that are conducive to causing rot. I’m constantly amazed by the number of fellow SPI’s who are also licensed home inspector’s that I hear use the term “dry rot”. But then again, so do most contractors, realtors and everyday folks. This is why I wanted to make this blog, to shed some light on what “dry rot” really is.

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Unsound wood has wood decay fungi present. These fungi are, to quote the Washington State Department of Agriculture, “the most important organisms to cause decay in wooden structures in the Pacific Northwest.” Wow. Rot is considered more important, or a more serious threat than subterranean termites, dampwood termites, anobiid beetles, carpenter and moisture ants. It’s estimated that roughly 10% of US lumber sales can be attributed to replacement of decayed wood in existing structures. That number expressed as a dollar amount easily approaches the billions. In our climate, where rain, and humidity are high, it’s important to engage with knowledgable professionals who understand the in’s and out’s of wood decay and how to locate the conditions that cause it.

So what are some key facts about wood decay?

• Wood decay fungi are the most common Wood Destroying Organisms in Washington
• The best way to prevent and control wood decay fungi is by eliminating excessive moisture
• Mold (a type of fungus) is a wood inhabiting organism, not a wood destroying organism

I’m trained to look for three types of fungi that degrade wood: brown, white and soft decay fungi. Brown rot fungi, are what most people who are untrained to diagnose types of wood decay call wood rot. This is because when it dries out it has the appearance of petrified wood. Let’s take Douglas Fir and use it as an example for what types of damage brown rot fungi can cause, since that’s what most homes are framed with in the Pacific Northwest. We can identify this type of damage by looking at the impact on the grain of the wood: in softwoods like Douglas-fir, numerous cross breaks form perpendicular to the grain.

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I will be doing a follow up to this blog in the coming weeks, but if there is anything that I want to get across it’s that when you hear someone use the term dry rot, there is a good chance that person doesn’t really know what they are talking about. It’s important to challenge the notion that issues such as decay fungi or rot and your home aren’t serious conditions that can affect decisions when buying, selling or simply living in a home. Hiring a trained professional to accurately diagnose the conditions and types of damaged wood at a property are invaluable pieces of information to have!

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Read here what a pest and wood destroying organism inspection is!