Wood Lining to Folding camper is wet

the best solution is to remove the spongy wood and replace with marine plywood

one possible fix is to glue(liquid nails) 4x8 vinyl sheets(used for bathroom walls and ceilings) over the spongy wood you should also determine where the support ribs are located and use rust proof exterior ( like deck screws) and put a washer through the screw and screw through the vinyl and sponge wood into the rib/stud to secure the vinyl do this about every 10 inches on the supports

finally caulk the edges and seams and put a lattice type of slat(1inch wide by 3/8 thick by 8 ft long on all exposed seams

tools needed small gig saw variable speed drill
caulking gun

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