What are purple spots?

by Sandra
Purple spots appear on the underside of a new patio cover (GAF roof) when it rains. Both the roofer and a GAF inspector can't figure out what is causing it. They appear in one area of the cover. This same area was getting green spots with rain after their first installation (it leaked and they had to replace it) Now they are purple, many more and much bigger. Time after time this roofer has had to come back to "fix" things that weren't done properly since the initial installation of the house and patio cover roofs 1 1/2 years ago. Does anyone know what could be causing the spots and what needs to be done to fix it?
Purple spots after it rains
  10 answers
  • 360 Sod (Donna Dixson) 360 Sod (Donna Dixson) on Mar 14, 2012
    I hate to ask probably a dumb question but what is above it?
  • Is this a painted plywood or?????
  • Stephanie B Stephanie B on Mar 15, 2012
    It could be the paint. There is a new paint for ceilings that goes on purple and dries white so you can tell where you've painted, I found out the hard way that when it gets wet again it turns to purple.
  • KMS Woodworks KMS Woodworks on Mar 15, 2012
    I'm trying to figure out what the ceiling material is...is it plastic of some kind ?...painted plywood?. The pic is a bit fuzzy...I have seen some "inks" bleed out when painted form marks on plywood and such.
  • Stephanie's guess is mine as well - what did they paint this with?
  • Peace Painting Co., Inc. Peace Painting Co., Inc. on Mar 16, 2012
    Do you see any other water signs like brown moisture rings? This is a wild guess: The paint could have been comprimised from the previous leak events. If the roof is fixed, now when it rains the paint is so comprimised that simply the moisture in the air is activating the weak, possibly mildewy spots to show up. If so, BIN primer will block the stains from coming back but won't work for long if there is still a leak from above. CP
  • Is that purple..? Uh-oh... my past sins from the '70s are coming back to haunt me.... Seriously, the answer is more than likely in one of the great answers already given. Think the key would be if it is in fact related to moisture, is the moisture coming down thru the material or is it a "surface" moisture from underneath (high humidity/condensation) that is causing something to bleed thru or grow..... and how long after the purple rain (oops, sorry), I mean the rain does it show up?
  • Donna McCrummen Donna McCrummen on Mar 16, 2012
    Underside of a new patio cover? What is that?
  • Rich M Rich M on Mar 27, 2012
    that looks to me like tar may be dripping down from shingles,green is mold ya got a leak i would say
  • It could be from a leak. If Sandra would return with full info we might puzzle it out. But with over forty years in this business, I have only seen tar drip down from shingles once and that was when the house was burning down under them.