Re: Galvanized roofs

Tony Thompson

Schuyler Larrabee wrote:

I think the greater prominence of peeling in those locations is that the car (and therefore the roof) flexes more at those points, and the “working” of the joints tends to crack whatever protective coating, car cement, paint, galvanizing, whatever, which permits the enemy, water, to penetrate to the victim, steel.

     This is certainly true, though galvanized coatings are not brittle. Note also, though, that galvanizing often fails at sharp corners, for example along the edge of the raised panels in a roof. Paint is thinner there. As Schuyler says, as soon as paint/car cement exposes the galvanized. it is at first protective (that's its purpose) but as more and more galvanized is exposed, eventually a pinhole begins to rust. All downhill from there <g>.

Tony Thompson

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