The wood around our French doors is rotting. How do we fix it?
Q: When our dog was a puppy, she chewed the wood by the French doors leading to our deck. As time went on, it got progressively worse. Now a piece of the wood has fallen out and the area around it looks rotten. Is this fixable?
A: When you’re trying to fix rotten wood, wherever it is, there are basically two options: Fill it with epoxy or replace it.
Filling with epoxy — a process that also involves treating the remaining wood to prevent future rot and to stiffen soft areas — makes sense if the rot isn’t extensive and the wood has an intricate shape or is located where removing and replacing it would be difficult. If you have round porch columns that are rotted at the bottom, for example, patching would be much easier than making a new column and shoring up the porch roof while you swap the old column with the new one. If the bottom of the door itself were rotten, that, too, might be a good candidate for patching with epoxy.
In your case, the picture you sent shows damage confined to a short section at the bottom of the door jamb. The door itself and even the trim over the edge of the jamb don’t show damage. The jamb, though, has only a little white paint still on it. Enough has peeled off that you can see that it isn’t a single piece of wood; instead, it’s a piece glued up from short segments that have interlocking, “finger-jointed” ends. That’s pretty clear evidence that the door was sold as a pre-hung unit made by a company that was cutting costs by shipping jambs that were only pre-primed, not painted. White primer paint, when new, looks about the same as white exterior paint. But primer is designed to stick well and make a good surface for paint. It isn’t designed to stand up to wet weather over the long term. Even if your puppy hadn’t been so intent on gnawing the wood, there’s a good chance you’d be seeing rot by now anyway if the jamb wasn’t painted.
This problem is so common that several companies have come up with kits designed so homeowners with only a few tools can fix the damage. Crescent Door Works sells what it calls the Boss-Rx Door Frame Rot Repair Kit. It’s made of PVC, a plastic that doesn’t rot and can be painted. KS Hardware makes a similar repair kit, but the parts are pre-primed wood. The two types differ in height (8 inches for the Boss; 12 inches for the KS Hardware), and the shape of the top edge. The Boss accommodates a lap joint with the part of the jamb you are keeping, which helps ensure a watertight installation even if you don’t cut as precisely as you should. The KS Hardware design uses a butt joint, which is easier to make. The Boss has a narrow vertical groove for weather-stripping, important if your existing jamb has that; you could fill the groove with caulk if you don’t need it. The KS Hardware pieces don’t have this feature. Both companies offer kits for jambs 4 9/16 inches wide and 6 9/16 inches wide.
Instead of buying a kit, you or someone you hire — maybe a home repair service because it’s probably too small a job to interest most contractors — could replicate a replacement piece from wood. Look at the websites for the kits to see what’s involved.
To install a kit piece or a custom-made patch, you need an oscillating multi-tool, such as the DeWalt cordless MAX XR fitted with a plunge-cutting saw blade, and a two-part paste epoxy, such as JB Weld or PC-7. If you want a lap joint at the top, you also need a sharp chisel.
To install a patch, start by removing the door. Tap up on the hinge pins with a nail so you can lift the door out without removing the hardware. It helps to have an assistant. Also take off any weather-stripping on the damaged jamb, and carefully pry off the exterior trim along that edge.
To accommodate the lap joint, the Boss instructions say to make a horizontal cut with the oscillating tool 6¾ inches up from the bottom. Cut or remove any nails or screws and wiggle out the damaged piece. Then make another parallel cut 1¼ inch higher — but only ½-inch deep. Make a few parallel cuts ½-inch deep below that to make it easier to chisel out enough wood to create a recess ½-inch deep. The patch should fit right in, but you can fine-tune the fit, if needed, by using the chisel to pare back excess wood on the jamb. If you’re using a patch that has a butt joint on top, just draw a line at the appropriate height and cut across it with the oscillating tool.
Spread painter’s tape along the top outside edge of both the jamb and the replacement piece, to prevent smearing epoxy over the face of the jamb. Mix and apply the two-part paste epoxy. Add a screw or two if the fit isn’t snug enough to keep the patch in place on its own. Let the epoxy set as long as the manufacturer recommends. Sand the jamb above the patch to remove all of the loose paint and gray wood fibers. Apply primer, then paint.
If cutting out the bottom of the jamb sounds too scary, or complicated, the other way to repair the damage is by hardening the soft wood and preventing additional damage with a consolidant, and filling the missing space with epoxy. Get a product such as Abatron’s Wood Restoration Kit, which contains parts A and B of LiquidWood, the consolidant, and parts A and B of WoodEpox, the patch material. Read the full instructions on the label or the technical data sheet (you can find this online).
The materials need to be applied to clean, dry wood. As you prepare the damaged area for the repair, also prep for eventually painting the whole jamb. Sand off flaking primer and most of the gray, weathered wood on areas that are otherwise sound, and wash the jamb with water to clean out any grit or bits of moss or lichen. When the wood has dried, mix the two parts of consolidant and brush it on to the damaged area. Repeat until the wood is saturated. While the consolidant is still tacky, mix the two parts of patch material. Apply it with a putty knife or a gloved hand, and smooth the surface as best you can. Once it dries, usually in an hour or two, sand the surface smooth. Apply primer and then paint to the whole jamb, including the patch.