What Does Dry Rot Look Like?
Here’s what you need to know to spot (and stop) the rot
Dry rot is caused by a fungus that spreads from trees and untreated timber via spores.
You’ll know it’s dry rot if you notice an orange color or brittle texture.
Stopping wood rot requires catching it early and acting fast.
There aren't many things sturdier than wood, but that doesn't mean this beloved building material is invincible. Even if you take every measure to maintain its health, it may still fall victim to issues like dry rot. Dry rot is a byproduct of a specific fungus that can transfer from the trees outside to the wood in your home via airborne spores.
But what does dry rot look like, and how do you tell the difference between it and other wood ailments like wet rot? Learn how to spot, treat, and prevent it and what can happen should you wait too long to fix the problem.
Common Causes of Dry Rot
Wet and dry rot often get lumped together, but the two don't have a lot in common. The first is often a result of mold after water damage, but dry rot doesn't require moisture to form.
So, what is dry rot? This phenomenon is directly linked to a fungus called Serpula lacrymans, which can form on wood outdoors and track its way into your house without proper preventative measures in place. And it doesn’t only affect wood. If not spotted soon enough, it can spread to and infect your home at large—even the parts that aren’t made from lumber.
Here are all the ways this fungus can sneak into your home.
Forest Environments
The dry rot fungus is naturally found in densely wooded areas like forests, which means your home has a higher risk of becoming infected if you live in such an environment. What’s worse, fruiting mushrooms from the fungus release spores that are carried by the air through windows and any unsealed cracks or gaps in your home, despite your best efforts.
Contact with Infected Timber
Bringing untreated timber into a home is the fastest way to accidentally infect it with dry rot. Even if the wood itself doesn’t appear infected, there’s still a good chance it could be carrying spores with it.
Use of Untreated Timber in Original Construction
Dry rot spores can remain dormant until activated—which means that they can be lying in wait in older homes that were built with untreated wood. If you suspect that this is the reason for your wood woes, hire a contractor near you to assess how deep the damage goes. They’ll be able to tell you whether the problem will be an easy fix or if it will require a complete structural overhaul.
Warm Temperatures
Although dry rot can activate at temperatures between 37 and 79 degrees Fahrenheit, it tends to prefer warmer conditions of 68 to 79 degrees Fahrenheit.
How to Identify Dry Rot
Wonder no more—here are all the signs that will clue you in to dry rot.
Brittle Wood
Unlike termite damage—which will hollow wood but won’t fundamentally alter its texture—dry rot makes timber brittle and weak. If you’re not sure how to tell if your problem is dry rot—or something else like black or white mold—all you need is five minutes and a screwdriver to find out.
Place the tip of the tool on an affected area and gently apply pressure. If the wood punctures easily and then crumbles into small, cube-like sawdust afterward, you’ve got wood rot on your hands.
Orange Dust
Changing colors is another feature of dry rot that you won’t find with wet rot. A dusty, orange color is the most common one you’ll get, but this fungus has also been known to produce shades like white, brown, and light or dark purple. By contrast, wet rot will darken wood, but it won’t produce a drastic color change like its counterpart.
Musty Smell
A wet, mildewy odor accompanies wet rot, but dry rot’s odor is much more unique, with notes of earth and a mushroom-like smell.
Fungal Growth or Fruiting Mushrooms
Speaking of mushrooms, they’ve been known to pop up in severe cases of dry rot. What you’re more likely to find, especially in the early stages, is a fungal growth resembling a white film—it’s like a spider web, but stickier, thicker, and often in places you’d never catch a spider.
Though the terms are used interchangeably, wood rot and dry rot have different meanings. Wood rot is a broad term that describes various types of fungal decay in wood, while dry rot is a specific type of wood rot caused by the fungus Serpula lacrymans. Dry rot can thrive at a low moisture level and spread rapidly across plaster and even masonry to infect new areas of wood.
How to Get Rid of Dry Rot
In order to stop wood rot, you have to find it first. Once you do, here’s what kind of repairs will be required depending on how advanced the issue is.
Treat early infections with fungicide: If the dry rot is still relatively contained, use a fungicide with borate to stop it in its tracks.
Remove and replace seriously infected wood: Wood that’s past the point of no return must be removed ASAP to avoid contaminating the rest of your home.
Hire a specialist: Extensive rot is a problem that should be handled by a water damage pro near you.
Frequently Asked Questions
Unlike wet rot, dry rot can damage non-wood materials, too—which it’s why it’s so important to get it in check early on. The longer it goes untreated, the more likely it will spread to the rest of your home, including the parts that aren’t made of wood, putting your entire abode at risk of severe structural damage as a result.
The cost to fix dry rot ranges from $500 to $3,000 and depends on the extent of the damage and where it is. For instance, some elements are easier and, therefore, less expensive to fix than others—like floorboards, which will cost less to fix than dry rot found on the roof.
