Whether to Glue Panels to Stiles and Rails

The basic answer is no (don't glue door panels to frames), but there are some fine points raised in this discussion. November 15, 2011

How much humidity does it really take for kiln dried hard maple raised panels to expand and contract in interior cabinet doors? I ask because I always use spaceballs for door making but Iím thinking that at least just for miter doors I can glue the panel to the stile and rail frame to add more strength to the door. Iím a little worried about the panels expanding over time and breaking the frame. I live in South Florida which is exposed to a lot of humidity, but the good thing is that all homes have air conditioning.

Forum Responses
(Cabinetmaking Forum)
From contributor G:
Don't glue solid wood panels, period.

From contributor F:
Contributor G is dead on. If you want to add strength to your miters, use a spline, or tenon the miters.

From contributor R:
"But Iím a little worried". Never glue a solid wood panel to the frame! It will break the frame or the panel.

From Carl Hagstrom, Systems Administrator at WOODWEB
You can predict very accurately how much a solid panel will move based on the changes in moisture content. Check out our wood shrinkage calculator (link below) - you'll find your answers there.

By the way - movement is influenced by species. Hard maple moves more than just about any other species. Finally - be sure the read the Knowledge Base articles on wood movement found at the end of the calculator instructions . Understanding the how and why of wood movement is important stuff for woodworkers. Understanding how ambient humidity affects moisture content (EMC) is something surprisingly few woodworkers are familiar with.

WOODWEB's Wood Shrinkage Calculator

From contributor K:
Well, I'll be the contrarian here and say that there are instances where you can glue in panels. One is that you can put a dab of glue on the center (width-wise) end grain of a solid wood panel (as in cabinet door panel) to help keep it centered in the opening. Clamp the top and bottom rails tight to the end grain and you can forget the spaceballs and rattles.

The other is that at some point, cross grain construction is ok. The common rail and stile joint has a 2" piece cross grain glued to the stiles, and all is well. A rail width in excess of 12" may be considered a problem. A solid panel of 2-3-4" width can be glued in place without concern. I would not glue in a 12" wide solid panel.

Panels can be made of a stable material - ply, particle or MDF, veneered and then rimmed with a mitered solid wood 'raise'. This makes a stable panel and can be glued. Of course, ply, MDF, and other stable materials can be glued in place as panels of any width. They will help reinforce those slight tenons that are common in mass produced door tooling. Miter doors generally have less strength in the joint and will also benefit from glued panels when possible.