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A comment on Buy Hi-Resolution Satellite Images of Any Place on Earth. Parent comment

Re:Buy Hi-Resolution Satellite Images of Any Place on Earth by heliodor on Saturday January 21, 2023 @02:18PM (#34469341)
In Puerto Rico, roofs are flat and get dirty within a few months. You absolutely can easily determine when it was last powerwashed as well as when it was last sealed.

Sealing will leave you with a pure white roof for about a month or two. Powerwashing will leave you will light to medium gray. They'll turn dark gray to black within a few months in the parts where the water pools.

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Re:Buy Hi-Resolution Satellite Images of Any Place on Earth by oakwhiz on Saturday January 21, 2023 @03:03PM (#34469801)
It's different for dyed sealant, but there is a time while the work is being done where old sections are stripped back and the new material is drying. Lots of false positives from HVAC work etc. though.
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Re:Buy Hi-Resolution Satellite Images of Any Place on Earth by geysersam on Sunday January 22, 2023 @03:40AM (#34475520)
If this is such an issue, why not have sloped roofs? (Just curious)
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