Q. I'm veneering panels for doors, flat, more of less 2 feet square.  Should I veneer both sides of the door panel?   If I glue a paper backed veneer or a 2-ply wood backed veneer onto 1/4 inch plywood, should I veneer the other side?

If the veneered panels are “captured” in the door frame styles and rails, do I still need to veneer the backs of the panels?

Answer.  The short answer is “yes”.  If you apply veneer to one side of a panel, you should apply veneer to the other side of the panel.  The backer veneer can be a less expensive veneer species. You should veneer both sides of the panel, even if the panel is captured in the door frame styles and rails.

Applying veneer to both sides of a substrate balances the stresses.  This mitigates warping.  Its similar to what happens when a bimetal is heated.  The bimetal bends (warps) because the dissimilar metals have different rates of expansion.

Wood and wood veneers expand and contract depending on environmental factors such as heat and humidity.  When you veneer both sides of a panel, the effects of heat and humidity cancel each other out, and this helps to keep the panel stable.

Some people break the rules and, oftentimes, they get away with it.  This is especially true if the substrate or the panel is mounted to a sturdy surface (such as a table frame) or if the panel is framed with styles and rails (such as a cabinet door).

My advice:   Don’t take any chances.  Its not worth it.  There’s no sense in spending your time and effort creating a nice piece that you are proud of, only to have it warp because you didn’t apply veneer to the back side.