When to repair rather than replace rotted wood

Homeowners face a difficult choice with rotted wood: Should the wood be replaced or repaired?

In my opinion, if the wood is badly damaged and it is possible to replace it with a reasonable amount of work, replacement is the best solution. A piece of badly rotted trim that is easily pried off, for example, should be replaced, not repaired.


However, there are many situations where it is practical to repair rotted wood, although do-it-yourselfers need to use good judgment.

Wood can rot in places where it can weaken a structure. Porch posts, which frequently rot around the bottom because of their ++ exposure to water, illustrate why wood needs to be structurally strong if it is repaired.


Window sills, another frequent target of wood rot, are often good candidates for repair because they are difficult to replace and have limited structural importance.

Old-house owners face special problems, since some ornamental wood pieces might be difficult or impossible to match, and even time-consuming repairs might make sense.

Repairing rotted wood is a tricky procedure. Wood-patching products that are highly resistant to water must be used. Among these products are Minwax's High Performance Wood Filler, Mr. Mac's Wood Fix and Abatron's WoodEpox. The patchers are sold at some home centers, paint stores and hardware stores. WoodEpox is also available by mail -- call (800) 445-1754 for information.

Most rotted-wood patchers are two-part compounds that are mixed immediately before use to the consistency of putty. Once the putty has hardened, it can be worked much like wood and smoothed or shaped with tools such as chisels, rasps and sandpaper.

Before the putty can be applied, the wood surface must be properly prepared. Unless all rotted wood can be brushed and scraped away to a sound wood surface, another product called a consolidant must be used.

For High Performance Wood Filler and WoodEpox, the consolidant is a liquid resin that is brushed, poured or injected into the wood fibers. The consolidant hardens soft fibers into a firm surface that will grip the putty.

Minwax calls its consolidant High Performance Wood Hardener. Abatron's Liquid Wood is used with WoodEpox.

Wood is consolidated before using Wood Fix by brushing on a thin mixture of the powder and polymer liquid included in the Wood Fix kit. A thick mixture of the same compounds produces Wood Fix putty.


Read instructions for using rotted-wood repair products carefully before you begin. It is also important to observe all cautions. For example, Minwax High Performance Wood Filler is flammable and has very strong vapors. I use this product for outdoor repairs only, and do all mixing outdoors. Goggles and rubber gloves should be worn to protect the eyes and skin.

Most of the rotted-wood putties also have a limited working time -- only 15 minutes for High Performance Wood Filler, for example. Mix only as much as can be used in the working-time period, since any leftover putty will harden and have to be discarded.

PTC When filling large cavities, use chunks of dry wood to help fill the space. Spread the interior of the hole with wood putty, press in a block of wood that fills most of the void, then cover the block with more putty.

When the putty hardens in a repaired area, tool and smooth it to match the surrounding surface. Use sandpaper for the final smoothing.

Hardened putty can be either painted or stained, but paint conceals the putty best.

Sanding can be messy and tiresome, but having the proper equipment can save time and reduce dust.


One of the best sources of sanding equipment I've seen is the Sanding Catalogue, a North Carolina company that specializes in mail-order sandpaper, sanders and accessories. Abrasives in a wide variety of forms -- belts, discs, rolls, sleeves, sheets, cords, blocks and pads -- are available.

To get a free copy of the catalog, call (800) 228-0000 or write the Sanding Catalogue, Box 3737, Hickory, N.C. 28603.