Introduction

Epoxy is the perfect material to make permanent repairs of rotting window sills, door jambs and exterior molding that are difficult to remove and expensive to replace. Epoxy is easy to handle too. You mix it like cookie dough, mold it like modeling clay and, when it hardens, you carve and sand it just like wood. It sticks like crazy and is formulated to flex and move with the wood, so it won't crack and fall out like some exterior wood fillers.

Overview: Epoxy Basics and Where to Get It

In this article, we’ll show you how to mix, apply and shape epoxy wood filler to create a long-lasting repair on damaged or rotted wood. We’re using a system of both liquid and putty-like epoxy made specifically for wood repair. The procedure we’re demonstrating is for cosmetic repairs. If a structural (weight bearing) member has been weakened by rot, you have to use other methods or in some cases special types of epoxy.

Once you learn a few tricks for mixing and applying the epoxy, you’ll find it’s as easy to use as Play-Doh. Most repairs will take only a few hours, using tools you probably already own. You’ll need a hammer and chisel, a drill, and wood rasps and files, depending on your repair. Other materials and supplies are listed in the story.

You will find many brands of epoxy. The exact mixing and application procedures vary a bit depending upon the manufacturer. Follow the manufacturer’s instructions carefully. The brand we’re using has a two-step system, which consists of two types of epoxy, a syrupy liquid consolidant and a putty-like wood paste filler. The liquid consolidant soaks into the wood fibers and hardens to form a solid base for the outdoor wood filler. As with any other epoxy, both the consolidant and the best exterior wood filler consist of two parts, the resin (part A) and the hardener (part B). Mixing the two parts according to the manufacturer’s instructions starts a chemical reaction that causes the epoxy to harden.