MAINTENANCE : Keep Cool to Prevent an Attack of Dry Rot

Dry rot, or decay, can affect your home, your boat or even your camper. A fungus attacks wood and causes decay when conditions--mainly moisture and warm temperatures--are right.

Repair or replace rotted wood quickly so the fungus will not spread.

What Rotted Wood Looks Like

Sometimes the fungus is visible. It grows out of the wood surface, appearing as mottled white or brown patches, strands or vine-like structures. The wood may be white and spongy or brown and crumbly. Wood with interior rot may sound hollow, feel spongy and yield easily to the probe of an ice pick.

Where to Look for Rotted Wood

Look for rotted wood in wet basements, near plumbing and in wood that touches the soil or is exposed to weather or water. The fungus usually enters the end grain--the base of a foundation post, the joint of a beam or a seam where a window frame butts against the sill. Pay particular attention to the windward side of your house or anyplace else where wind can force rainwater deep into a joint or crack. Flaking or discolored paint are symptoms.

Prevention

To prevent rot, or at least slow its progress, keep affected or potential decay sites dry, cool and adequately ventilated. This is not always possible without elaborate drainage and ventilation arrangements that are best built into a structure when it is first constructed. But there are often simple measures to control moisture and increase airflow in crawl spaces and basements by adding vents and keeping water from puddling around the foundation.

Structures are usually difficult to replace; call in a professional. You may be able to fix parts such as windowsills, door frames, porch rails and siding by cutting away the affected area (plus six inches on either side) and splicing in fresh wood. But it is generally better to replace the whole piece.

Repair

If the dry rot has infected a small area that does not bear weight--windows and doorsills, floors and walls adjacent to sweating plumbing fixtures or very small spots and beams--scrape down to good wood, apply a wood preservative and refinish.

You can often repair for deeper damage with an epoxy resin, available in most boating supply or hardware stores. The compound is sold in two containers that must be mixed. Drill several quarter-inch holes deep into (but not through) the affected wood. Then mix the two parts of resin in a plastic squeeze bottle and inject it slowly into the holes.

Over several days, the resin will seep into the pores of the wood.

Complete the job by coating the surface with an epoxy filler. Smooth and sand when thoroughly dry, then refinish as required.