All About Dry Rot

Posted on Posted in General

What exactly is dry rot? Dry rot has been the cause of two major accidents in California in 2015 that caused the deaths of seven people. In June of 2015, a deck in Berkeley collapsed and killed six students. The following month, a stairwell in an apartment at Folsom collapsed and killed a 26-year old man from San Francisco. Both accidents were caused by dry rot.

Dry rot is the most common cause of timber damage. It is the term given to wood decay caused by certain fungi that digest those parts of the wood that gives wood its strength and stiffness. Despite its name, dry rot results from too much moisture in contact with wood. The dry rot fungus has the unusual ability to transport water from wet areas allowing the fungus to thrive on relatively dry wood and without intervention may lead to the wood’s disintegration. As timber accounts for anywhere up to 70% of the basic structure of a house, a dry rot outbreak is an issue that should not be overlooked, as it can be a serious threat to a building’s shape and integrity.

What does dry rot look like? Dry rot takes on different characteristics depending on is stage of development. It flourishes in poorly ventilated conditions and will most often be found in enclosed hard-to-reach areas such as under the floorboards, behind skirting boards, door frames or casings, and beneath stair treads. As these are often unseen, more often than not, dry rot is already in its advanced state when detected.

Dry rot will initially appear as a white or grey cotton wool-like substance.


Then, it would have a “pizza-like” appearance, round with a rusty deep red color with the outer parts of this growth in white.


The decayed wood then takes on a darker appearance with cuboid cracking or checking that becomes brittle and eventually crushing the wood in to powder.


Even without physically seeing a dry rot outbreak, the presence of a damp, musty, fungal smell in a common indicator of a dry rot issue. Although the smell can also point to wet rot, it is a certainty that whichever the problem is, the main culprit is dampness.

Compared to wet rot however, dry is more difficult to treat because it has the ability to spread over relatively dry timber and other building materials in a property to find a source of food. Wet rot outbreak on the other hand, is confined to the source of moisture and cannot spread out the building unless it has direct contact with water in whatever form.

It’s certainly obvious that the best way to dry rot prevention is eliminating the source of excess moisture. It may be as simple as fixing a leaky pipe or as complicated as stopping the infiltration of water in a basement foundation. It is highly advisable to get a professional to do a thorough inspection of the building to see if there are serious damp issues. Even if you do treat the area where dry rot thrives, if there are unresolved damp issues, dry rot will progress further doing more damage resulting to more costly and time-consuming repairs.

If you are in Berkeley, Folsom, Los Angeles, South Bay, Long Beach, Palos Verdes, Downey and other surrounding areas in Southern California, you may call Westside Company to do a thorough house inspection for damp issues. Our telephone number is 310 994 4626. You may also e-mail us at

We are a professional waterproofing contractor with headquarters in San Pedro, California with decades of experience in resolving issues with moisture both in residential and commercial properties. We certainly have the manpower and the expertise to inspect your property for the causes of your dry rot issue. Consultation is free and we will present you resolutions on how to eliminate your moisture issue. It goes without saying that our team of professionals will be able to work on doing the necessary repairs to timber damage on walls, ceilings, decks, balconies, stairs, railings, and walkways, among others.

It is worthwhile remembering that removing excess moisture is the first step in the treatment and prevention of dry rot infestation. Once the source of moisture has been eliminated, the damaged wood needs to be replaced as mere remediation will not strengthen its already weakened state and will pose as a safety hazard.

There are other simple ways to prevent dry rot.

  • Examine the grading or your yard so water won’t collect at the structure’s foundation.
  • Make sure there is proper ventilation in your bathroom, kitchen, and attic. Inadequate ventilation encourages the spread of dry rot.
  • Regularly check for plumbing leaks especially in those areas, which are not seen everyday such as underneath vanities and cabinets. If you do find leaks, have it repaired immediately.
  • Have your roof checked once a year to identify and prevent potential water damage.
  • Clean your gutters regularly to prevent clogs that could cause water to back up and spill on to fascia and siding.
  • Have your deck, balcony, stairway, and/or railings properly sealed.
  • Have wood siding installed and sealed properly by a skilled siding professional.
  • Don’t lean anything against your siding such as old plywood, tools, and ladders.
  • Check to see if your sprinkler system is appropriately placed. Make sure that when it’s turned on, water coming out from the sprinkler does not hit the structures exterior causing unnecessary over-saturation.
  • If you decide to take on an exterior DIY project, always use decay-resistant or pressure-treated lumber. Also, treat, stain or paint all sides of each lumber piece before assembly.
  • Additional tips if you are building something outside: it has to be able to shed water. Decks, porches, railings, window sills all have to be designed to shed water to make sure it doesn’t get stuck and creature a moisture-rich environment where all types of fungus may grow. Also, when you nail or fasten wood (especially on horizontal surfaces) it is worth the extra effort to countersink and plug the fasteners. Doing so prevents fasteners from rusting and also avoids any divots in the wood that will catch water.

The key to dry rot prevention is limiting or eliminating all sources of moisture.