How to Repair Rotten Wood

If you have ever owned a wooden home, you may have had to deal with rotten wood. The fact is, it isn’t as hard as many seem to think. The first step is to identify the problem area and ascertain how much wood you actually need to repair. The area needing repair seen most often is the bottom foot or so of the exterior wall, and sometimes under windows where moisture has seeped in. Other areas that seem to rot quickly is the chimney where it meets the roof, and exterior corners, where rain has the best chance to wash over it. Rotten wood can occur anywhere in your home, so be vigilant against moisture getting behind the wood through seams and cracks. Keep these problem areas trouble free by caulking every few years.

Once you decide the width and length of the area to be replaced, use a chalk line to mark the lines you will need to follow with your circular saw. Remember that the plywood needs to end at the center of a stud. Set the blade depth for the thickness of the wood, being careful not to cut deeply into the wall, as this will damage plumbing, studs and wiring. Once you have the old plywood off, inspect the studs underneath for damage. Replacing rotten studs is impossible without removing the entire sheeting in that area of the wall, but you can just replace the rotten section of each individual and install splints in most areas. If building code requires you to replace the entire stud, then you will have to comply, although it is rare that building code requires this extra step.

When replacing studs, remember to remove and replace one stud at a time. Removing multiple studs is a recipe for disaster, as the entire roof and wall system is supported by the studs in the wall you are repairing. Removing all the studs at once will cause irreparable damage to the roof and soffit. Simply pull one stud out, replace it and nail it off. Use nails, never screws, and drive two on one side and one nail on the other at both the bottom plate and the top plate. If the bottom plate shows evidence of rot, it will also need to be replaced. Replacing bottom plate is an extensive repair, and will require removing a good portion of the exterior sheeting. Use casehard nails to install the new bottom plate, unless the flooring is a material other than cement. Remember that screws should never be used for structural framing, due to their low shear strength.

Once the framing studs and bottom plate are squared away, you can install the new plywood. Simply trace the old wood, or pop chalk lines to provide a saw guide. Although you can use sawhorses, they are not necessary here, as you can cut the plywood on the ground, provided it is flat, and use the depth gauge of your circular saw to keep the blade out of the dirt. Set your new sheet of plywood on the studs and hand drive one nail and leave part of the shank exposed, so it can be removed easily, if necessary. Double check to be sure the plywood is sitting in the right spot and that it ends in the center of a stud.

Once you are comfortable with the alignment, nail off your sheet of plywood, spacing four inches apart on the perimeter and six inches apart in the field. Some areas require special z-bar flashing, and some require the joint to be caulked. If you are installing siding or sheeting over the plywood you have repaired, there is no need for any further work on the rotten wood. If you are required to install z-bar flashing, you will find it much easier to install with a nailgun, as you will have to install nailer blocks in order support the z-bar . Simply nail a short cross piece between your two studs at the horizontal seam you have created for your wood repair and nail the z-bar to it. Using a pneumatic nail gun cuts the time for this project in half.