While cedar shake roofs are normally very durable, they can be rapidly damaged by excess moisture. Older cedar roofs are especially vulnerable. Cedar contains natural oils that can repel pests and fungi, but these oils are water-soluble. Rain will eventually wash most of the oils out of the shake, and excess moisture can lead to the shake becoming infested with fungus.
Fungi cause the shake to decay, reducing its ability to withstand high winds. If your cedar shake roof has been damaged by excess moisture and your shakes are starting to rot because of a fungal infestation, you'll need to repair it to prevent your attic from leaking. To learn why excess moisture damages cedar roofs and how you can repair the damage, read on.
How Does Excess Moisture Damage a Cedar Shake Roof?
Cedar shakes are porous, meaning they'll absorb some water when it rains. Normally, they'll dry out when the sun comes out after the rain. If the cedar shakes are shaded or covered in moss or leaves, this will prevent the moisture from evaporating and trap it within the shake.
When moisture becomes trapped in a cedar shake that has lost all of its natural oils, the cedar shake becomes a suitable host for fungal spores that naturally float through the air. Fungus uses the cedar as a food source, and it will slowly break down the cellulose inside the shake as it consumes it. This will weaken the shake and cause it to become spongy and more porous.
A cedar shake that has become badly rotted due to fungus is so weak that you can crumble it apart with your bare hands. High winds during a severe storm will easily destroy them and open your home up to leaks. You'll need to repair your roof in order to prevent this from happening.
How Do You Repair a Cedar Shake Roof That Has Been Damaged by Moisture?
When repairing a cedar shake roof that has been damaged by moisture, the first step is to examine all of the shakes by hand. Any shakes that feel spongy or soft will need to be removed and replaced. Removing the old shakes requires carefully prying up the nails that attach them to the roof and nailing down a new shake in its place.
After all of the decayed shakes have been replaced, the roof will need to be washed with a biocidal solution such as copper naphthenate. This will kill all of the fungus, preventing it from continuing to cause your roof to decay. A biocidal solution will also soak into the cedar shakes on your roof, providing them with protection against a second infection.
You'll also need to address the source of the excess moisture on your roof. If leaves are trapping moisture against your roof, you'll need to have your roof cleaned more often. If shade is preventing rain from evaporation, you'll need to trim the trees that are casting shade on your roof. When your roof is allowed to dry in the sun, you'll minimize the risk of your roof being damaged by excess moisture.
If you have a cedar shake roof that has been damaged by moisture, call a roof repair service in your area and have the shakes inspected. Any shakes that have been weakened by fungal decay will be replaced, restoring your roof's ability to withstand heavy storms. Afterwards, you can remove the remaining fungus by having a biocide sprayed onto your cedar shakes.
For more information, contact a roofing contractor near you.