Gutter leaks can do hidden damage when siding masks the problem.

The problem

Rainwater leaking from a gutter ends up behind siding and causes a wall to rot.

At some point in the past, an owner had vinyl siding installed over old siding. The extra thickness of the vinyl siding and its accompanying insulation made the outer edge of the siding extend out beyond the gutter cap.

Other types of siding may also telegraph water problems in a wall, be it staining, rot, efflorescence, softness or swelling. Vinyl is the rare siding product that remains completely unaffected by water behind it. That can be a virtue and a vice.

Flashing or caulking, if installed (which is rare), would be of no consequence, as that would only seal water inside the wall.

So how do you know if you have water getting behind vinyl siding? In a rainstorm you may see water at the top of the foundation, running down or leaving a stain. If it is a cantilevered area, as in this case, place your hand at the base of the wall and feel for water and rot.

The repair

Obviously both the vinyl and old siding must come off the wall in the affected areas. Exploratory work is needed to determine how far the rot has extended, with repairs performed as necessary.

When the structural repair is completed, the gutter must be removed, cut back several inches, capped and resealed. When siding is put back behind the gutter, the lowest piece of flashing running down the pitch of the roof above must be fashioned to divert water into the gutter, not behind the siding.

Darrell Hay is a local home inspector and manages rental properties.