The Good, the Bad, and the Ugly – Structural Rot

Under no circumstances can structural rot be considered ‘good’. Rot is rot. So in this instance we’ll skip the good and move straight on to the bad and the ugly.

Kelowna Home Inspector - Building Pro - wood rot in balcony support post

Under no circumstances can structural rot be considered ‘good’. Rot is rot. So in this instance we’ll skip the good and move straight on to the bad and the ugly. Wood-frame construction is the chosen building option for millions of homes in Canada, and you want to ensure that you have a solid and sustainable structure to house your family. Wood rot is a hazard; it weakens structural wood componets, causing instability and if ignored, eventual collapse. What was once a solid and safe structure can become hazardous to your family’s health and safety. Not to mention that repairs for wood rot can be an expensive proposition. In this article we discuss structural wood rot: its origins, treatment, and prevention. 


All wood is subject to rot under the right conditions. Rot is the result of a natural process when fungal growth breaks down the wood and recycles nutrients from fallen trees and forest debris. Fungi can estabish colonies in our home if wood componets becomes damp. Any wood that remains damp is an invitation for fungi colonization, resulting in the rot that can damage the structural integrity of your home. Rotted wood can be found anywhere in the home, from the basement to the attic, as well as outside the home. There may be rotted siding or trim. The basement may have remained wet due to perpetual water penetration, or a pipe leak here or anywhere else in the home may have caused wood to rot.  The attic may have rotted wood from a leak in the roof. Almost all homes, whether a house, townhouse, duplex, condo or apartment, have had some water penetration. In most of cases, the leak is found and repaired before fungi take hold, preventing the rot. In some homes the moisture is not seen before rot becomes a problem. A problem that, unless treated, will only get worse.


From outside to inside vital structural components such as beams, framing, shingles, panelling, doors, floors, and trim are all made of wood. A proactive approach to home maintenance is always the best thing you can do to prevent structural rot. Without moisture, you will not have rot. It is important that you check areas inside and outside your home for moisture. Inside look for damp areas caused by leaks originating inside the home or leaking through the structure from the ouside. If you see condensation on your windows, the humidity levels in the home may be high. When humidity is high condensation may form on cold walls and penetrate the wall finishes without you noticing. If you have high humidity, use your kitchen and bathroom exhaust fans. If you don’t have them install them. Make sure the dryer duct is still connected to the exterior vent, to avoid blowing all that moist air into the house. Outside, insure water moves away from the house, make sure the ground slopes away. Keep the ground well below the wood structure to prevent water from wicking up into the wood and creating a home for fungi. Keep plantings away from the walls to allow air circulation to dry wet surfaces. Maintain your gutters and insure downspouts direct the water away from the foundation. Rot is a product of fungi growth. Control the moisture and you avoid the fungi and rot.


Rotten structural material will have to be removed and replaced. Before this is done it is important to remove the cause, excess moisture. First, locate and eliminate the source of the moisture (i.e. fix a leaking pipe). After the moisture issue is resolved replace any damaged wood that has become structurally weakened. Any existing sound wood that may have harboured fungi, and the new wood, can be then be treated with a borate wood preservative to prevent growth and kill any fungus already in the wood. Borate is a pesticide that kills the rot fungus. Depending on what part of the structure is damaged and how extensive, you may want to seek the proffesional help of a licensed carpenter or in extreme cases an engineer. Remember, repair it properly so you don’t have to do it again.

Or, if you’re unsure of any of this, go with the following option…

Hire a professional. A home inspector will inspect your home for moisture issues and indications of compromised struture. The inspector will advise you if any rot is found or any conditions that may now or in the future lead to rot. You will be given recommendations on how to repair the damage, whom to hire to make the repairs, and finally, what can be done to prevent water damage and rot in the future. Learning how to protect your home will help you avoid future problems.


Nothing is more important than the structural safety of your home. Rot undermines this safety; it is an invader that compromises and, if left unchecked, will conquer your peace of mind. Stop the rot before it has time to settle, check it if it’s spreading, and get rid of it by treatment or replacement if it has gone too far.

Our goal at Building Pro Inspections is to give the best possible inspection so you can make the best decision with confidence. For buyers and sellers, Building Pro has the expertise and experience you need. Please call us today for more information.