[TheForge] OT - Asphalt shingle rot? (Lichen)

[K Mayer]

>Date: Thu, 01 Jul 2010 08:36:35 -0500
>From: CGRAF <adveniam at att.net>
>
>I have seen steel nails rusted out because of the galvanic reaction 
>caused by water washing off of copper flashing.
>  While the copper strips will kill lichen etc and probably not do any 
>damage to the nails if the roof is steep enough, a flatter roof will 
>have problems.
>On a steep roof the nails rarely , if ever, get wet. On a flatter roof 
>the wet zone is larger as the water move sideways more.
>
>Lift a shingle and check the V made by the dust/water line. Are the 
>nails on the dry side (inside) of the V?

Simple cure:  use copper nails.

Ken
:-)