If you have wood paneling and it begins to bow or buckle, possible causes are rising and falling humidity levels, wall or foundation settling that make the walls shift and paneling nails coming loose. Whatever the reason, if the paneling is bowing, it can generally be reversed or repaired and then put back into place. All you'll need is a few tools to repair the bow.
Remove the paneling from the wall by prying out every panel nails with a claw hammer or pry bar. Once the nails have been removed, slide the pry bar blade or hammer claw between the paneling and the wall studs; gently pull the paneling away.
Fill a spray bottle with distilled water. Use only distilled water as it has no bacteria or minerals that can cause mold. Moisten the paneling liberally on the back side where it is bowed.
Lay the paneling flat in a warm area, like a garage or shed. Use a dropcloth if laying on dirt.
Place bricks or other flat, heavy objects directly on the bow. The combination of heat and moisture will cause the bow to straighten under the weight. Wait 24 to 48 hours and check. Repeat as necessary.
Refasten the paneling back in place with paneling nails and a hammer. Add extra nails where the bow occurred to prevent future buckling.