Fixing a Cracked Door Panel
The culprit isn't the wood, it's the paint
One of the panels in our exterior wood door has had a crack across its width for as many years as I can remember. I've tried to fill the gap with caulk, wood filler, and similar products, but the crack keeps coming back. Is there any way to repair it permanently?
— William, Zionsville, IN
Norm Abram replies: Sounds like a classic case of what happens when wood isn't allowed to move. Ideally, a door panel should fit loosely enough between the door's stiles and rails so that it can expand and contract as humidity levels go up and down. But paint buildup on the edges of a panel can grip the surrounding door so tightly that the panel literally tears itself apart when it shrinks. No amount of glue or caulk is going to stop that split from opening up again in dry weather.
To fix this problem for good, you'll have to free up the edges of the panel. If you're lucky, your panels are held in place with molding on one side of the door. All you need to do is pry off the molding and remove the panel so it can be either repaired or replaced.
Unfortunately, most door panels fit into grooves in the stiles and rails, so there's no way to remove them without disassembling the door, which isn't usually worth the effort. So I'd start by removing the paint or varnish that's holding it in place. You can work just on the cracked panel, but I'd be inclined to strip the entire door.
Once the panel edges are free, try to repair the panel in place. First, scrape out all the caulk and filler and other materials you've put in there. Then screw a couple of small wood clamping blocks about a half inch from each each other on opposite sides of the crack. Brush a thin coat of polyurethane glue into the panel's crack and clamp the two pieces together using the blocks for leverage. When the glue cures, remove the blocks, fill the screw holes, and scrape away the excess polyurethane. Sand both faces of the panel smooth and prime the repair. Or, if your door has a clear finish, reface both sides of the panel with peel-and-stick wood veneer. Whichever finish you use — stain or paint — just be careful not to let any of it seep into the joints.