we built and ICF house in AZ and used vinyl frame low-e windows. Of course wood is not a good choice for the hot and dry desert southwest. hence the vinyl. Here's the problem: the vinyl is getting this white powdery stuff on the surface and when it rains, it washes down onto the stucco and discolors the stucco. i tried wiping on a product like Armorall but i don't know if this will solve the problem. any advice?