How do you tell if siding needs to be replaced?

Most of this you can check yourself in twenty minutes with nothing but your hands and a walk around the house. Do it on an overcast day or in low sun — raking light shows surface damage that noon sun hides completely.

Run your hand down the wall. If it comes back chalky white, the finish has oxidised. On aluminum this is the normal end state and it means the finish is spent, not that the wall is dirty. Painting is possible but it is a maintenance cycle, not a fix.

Press and flex a panel in an inconspicuous spot. Sound vinyl flexes. Vinyl that cracks or makes a dry snapping sound has gone brittle with age, and that means repair options are closing — the panels around any damage will crack when the crew tries to work them.

Look along the wall from the corner, not straight at it. Waviness, buckling and panels standing proud of the course usually mean the siding was nailed too tight and has nowhere to go when it expands, or that something behind the wall has moved.

Check the butt joints and the bottom courses for staining. Dark streaks running down from a seam mean water is getting behind the panel there. Green or black staining on lower courses on a shaded elevation is usually organic growth, which is a cleaning issue rather than a replacement issue — unless the panel underneath is soft.

Push at the bottom edge of a few panels. Loose, rattling or unlocked courses are wind lift waiting to happen, and it almost always starts at corners and gable ends.

Now go inside and look at the matching interior wall. Peeling paint, bubbling wallpaper, soft drywall or a musty smell against an exterior wall is the sign that matters most. That is moisture in the wall assembly, and it changes the conversation from cladding to wall repair.

Compare the south or west wall against the north wall. If they no longer look like the same colour, partial repair is off the table even if a panel match technically exists.

Note whether heating costs have climbed with no other explanation. On its own it means little. Combined with visible gaps and loose courses, it points at air leakage through the wall assembly.

The dividing line in practice: isolated damage on a wall that is otherwise sound, flexible and unstained is a repair. Chalking across whole elevations, brittleness, waviness, or any moisture showing on the inside means the money is better spent on replacement than on patching a wall that will need doing anyway.

Written by the team at siding contractor in London, Ontario.