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Looking at a rooftop in Google Maps, I noticed a strange texture on it which was not at all apparent from a view on the ground. I viewed the same spot in Google Earth to look at it across time. The strange texture was present as far back as 2009 but after that, although the texture went away, that section of the roof does remain brighter than the rest of the roof consistently over time. On the ground it does appear slightly flatter on that part of the roof than other parts, could that have an affect, or be a clue as to what that texture actually represents?

What could cause this texture and brightness?

Current imagery from Google:
current image

2006 imagery showing non-textured roof but with a brighter coloration:
2006 imagery

2005:
2005 imagery

2003:
2003 imagery

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It is probably a rolled roofing or SBS roofing that has been sealed over using a white-coloured sealant that you can see around the flashing of the chimney.

The house already has a low pitch roof but there is a transition of the roof pitch to an even lower angle as you come down from the peak to extend the roof the additional ~10 feet required for the room on the backend of the porch. The street-facing gable runs down to the eave just to the right of the porch; The long ridge runs, unbroken from the front to back, so to cover the room behind the red doors you have to change the pitch at the point the porch gable butts the main roof slope.

So quite literally, the mismatched roofing is the slope face that has a lower pitch or angle.

Once a pitch on a roof is low enough (<4"rise per 12"run), water run-off is not quick; water will loiter around longer, pool, and potentially back-up under traditional shingles. Additionally, low pitches using traditional asphalt/composite shingles can make it easier for ground winds to catch and damage the shingles.

To avoid this, a rolled roofing or a SBS roofing system was installed and the odd white colour is simple the sealant they used on the seams. Or they used the white sealant to repair an aging membrane system. A lot of the sealants can be applied with a roller or mop and it never look 'good'.

  • Thanks for all the info identifying what's going on there. That makes sense and explains this abnormality not so much as a problem with the roof or data but as an appropriate difference in texture due to this section's pitch. This is a more detailed answer than the first and in a useful way, so I'm marking it the new accepted answer, although the first answer provided the picture to support it. – cr0 Jul 27 '17 at 20:39
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It's visible in Streetview in 2011 and 2014. Looks like the roof is covered in Tyvek or some other waterproof construction barrier cloth.

Streetview image

  • Didn't notice that, nice find. Any idea why that part of the roof would be consistently brighter in that 2006-2003 Google Earth imagery? It no longer has that Tyvek-like texture but could've had some other cover, or would the different roof angle be enough to give it such a lighter color? – cr0 Jul 26 '17 at 2:59
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    Could be a different material, could be due to different nadir angle, could be differences in color balancing. Or all three. – Marc Pfister Jul 26 '17 at 16:00
  • Though this answer was helpful and served as a starting point for other answers, the follow up by RomaH adds more useful detail, so I'm marking that as the new accepted answer. – cr0 Jul 27 '17 at 20:40

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