Black Stains on Roof

Old 10-28-04, 03:02 AM
Visiting Guest
Posts: n/a
Black Stains on Roof

We have black streaks on several areas of our roof. Any idea what causes this and can these streaks be removed?
Old 10-28-04, 05:51 AM
pgtek's Avatar
Join Date: Oct 2004
Location: north Carolina
Posts: 1,348
Received 1 Upvote on 1 Post
it might be some roofing cement that run for flashing due to heat
the sealer stip the shingles that leak
if low slop shingle
maybe the NIS adhesive was to thick and when the sun hit it it made it run

Old 10-28-04, 01:51 PM
Join Date: Jul 2002
Posts: 274
Upvotes: 0
Received 0 Upvotes on 0 Posts
I'm sure it's algae.
This is a question that is answered here in great detail on here quite often.

I LOVE this site, but it's "search" function leave alot to be desired.
I have tried looking for some of the earlier answers, have had no luck.

In short, it can be cleaned with a 1/3 water, 1/3 TSP (detergent), and 1/3 bleach mix.
Actually, the more bleach, the better....however, your landscaping around the house doesn't like bleach. That is why they say to dilute it with water.

Spray the mixture on the algae and let it sit for 15 minutes or so.
Then rinse it off with the water hose.
Douse your plants in the yard before your spray the roof to dilute with any runoff from your roof.

You may have to re-apply depending on how bad the algae is.

You could pay to have it done.
Do NOT get anyone that uses "high-pressure" washing.
It will knock the granules off the shingles.
Use only a "low-pressure" wash.

I wish I had more time to elaborate, but I've got to go.
Maybe you could have more luck with a search on this topic here.

Good luck.
Old 10-29-04, 03:23 AM
Visiting Guest
Posts: n/a
Thumbs up

Algae sounds about right. The area that's most effected was located under tree branches..however, there are several small areas that were not..but since we had such a wet summer, I guess anything is possible.
Thanks, I'll give the bleach mixture a try.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: