Dry rot is not only unattractive, it can threaten the structural stability of your home. Understand what causes dry rot, then assess whether repair is an option or replacement of the wood is a must.

What Is Dry Rot?

wood-rot A certain species of fungus causes dry rot. Its spores land on wood, and with enough moisture it thrives, despite the name. You may see white or grey growth on the wood and even a mushroom-like body if advanced. Other visible signs of dry rot include blistering, cracked or peeling paint , wood darker than surrounding areas, and green algae on the wood.

Window and door sills are most often affected by dry rot, but it can grow into non-wood surfaces in contact with the ground. It also can spread to non-wood materials such as plaster and mortar.

Test for dry rot by inserting a screwdriver into the wood. If it goes in easily or feels spongy, you likely have dry rot.

Repair vs. Replacement

Certain amounts of dry rot can be repaired, but it is not recommended if the affected areas provide structural stability to your home, such as with beams and joints, or even with flooring for that matter. In those cases, you should replace the wood instead of repairing it.

Whether you repair or replace the wood, you must eliminate the conditions that allowed the rot to thrive or face it coming back. Locate the cause of moisture buildup by checking for roof leaks, damaged gutters or downspouts , plumbing leaks and/or poor ventilation. You may need the help of your professional handyman to find and repair the issue.

How to Repair Wood Damaged by Dry Rot

If you are confident that the area with rotted wood is repairable, many products are available to strengthen and patch it. Start by removing as much of the infected wood as possible with a wood chisel. If you cannot reach it all, inject a consolidant into the wood through drilled holes. It will reinforce the affected wood fibers and bond with unaffected surrounding areas. A wood-patching product can then complete the repair. You apply the putty-like material to the rotted wood and shape it to the desired form using a chisel and sandpaper.

Keep in mind that with repair only, you run the risk of not getting all of the affected wood and allowing the fungus to spread deeper into the structure of your home. Only attempt repair if you have DIY experience with the work-otherwise, enlist the help of your professional handyman.

How to Replace Wood Damaged by Dry Rot

As noted with repair, only attempt replacement of rotted wood if you have sufficient experience. The work will involve:

  • Removing all rotted wood and an additional three feet of surrounding wood to ensure no fungus remains

  • Removing all plaster, skirtings, paneling, linings, and ceilings to ensure no fungus remains

  • Cleaning all surfaces, including steel and pipes, within five feet of the rotted wood or other material

  • Applying fungicide to all surfaces within five feet of the rotted area

  • Replacing with preservative-treated wood

  • Replastering or painting with a zinc oxychloride product

Throughout this project, all rotted materials will need to be removed from your home and disposed of appropriately. Again, as with repair, the goal is getting all of the affected wood and not allowing the fungus to spread deeper into the structure of your home.

Many homeowners also make the mistake of thinking dry rot is wet rot, which is caused by a different fungus. It looks wet and stays local, but it also requires repair or replacement of the affected wood. To be on the safe side, enlist the help of a professional whenever you spot rot in your home.

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