Q. The plywood panels in my garage doors have warped despite frequent paintings over the last 18 years. I now want to replace them. Which is the better choice: exterior-grade plywood or masonite? Should the new panels be primed and painted on both sides or only on the outside? Robert W. Baker Dover, Del.
A. Those 18-year-old plywood panels have proved the point that painted plywood has reasonable longevity. In fact, they might have lasted even longer had the wood structure behind them been more sturdy, the framing members closer together, or the panel edges and insides primed and painted before installation.
Some house door manufacturers will not guarantee their doors unless the same number of coats of paint are applied to both faces and all the edges.
Now, to answer your question. Either marine or exterior-grade plywood or tempered masonite are quite satisfactory as replacement panels.
Before applying the new panels, tighten the framing of the doors so they are rigid and without wrack. Back-prime the panels inside and out, both faces and especially all the edges, before applying them to the frame.
For what little extra paint and energy it takes, I'd also paint both sides and all edges of the panels over the primer.
Use only coated nails or screws. For a really super job, lay a bead of glue between the new panels and the old frame.
What's your home-building or upkeep problem? Forrest M. Holly, a former West Coast builder now living in Arizona, has been answering such questions in the column for the past 17 years. Send questions to the Real Estate Editor, The Christian Science Monitor, One Norway Street, Boston, MA 02115.