What's that growing on my concrete tile roof????
#1
07-07-16, 01:07 PM
What's that growing on my concrete tile roof????
20 year ago we needed to replace our Los Angeles English Tudor wood shake roof. Fire laws banned wood so we found concrete tile (16" x 8" and 9 pds each) that looked great! They have withstood all our earthquakes and droughts but a few years ago an odd reddish growth appeared. See attached pix. Anyone know what this is? If it's mold, is it harmful? How do I get rid of it? Any and all responses gratefully appreciated.
Joe Bronx
Joe Bronx
Last edited by PJmax; 07-07-16 at 02:03 PM. Reason: reoriented 1st pic- enhanced pic 1 and 2
#3
07-07-16, 02:25 PM
I appreciate your response but "I assume" concerns me. I've been warned not to use bleach until I
know what it us so I'm hoping some one recognizes it and responds. Many thanks!
know what it us so I'm hoping some one recognizes it and responds. Many thanks!
#8
07-08-16, 04:09 AM
I generally mix 40-50% bleach with water and will add TSP to the mix if needed. I'll wet the substrate first, then apply the bleach solution, let it set but not dry and then rinse. It may be necessary to retreat or scrub stubborn areas. An old broom works well for scrubbing.
Not sure why you've been warned against bleach, while I don't recall ever washing cement shingles I've used a bleach solution on all types of masonry with good results [brick, block, concrete, stucco, stone]
Not sure why you've been warned against bleach, while I don't recall ever washing cement shingles I've used a bleach solution on all types of masonry with good results [brick, block, concrete, stucco, stone]
#9
07-08-16, 01:53 PM
Many thanks for the detailed response. I'll try it. Bleach warning came from my brother in law who studied masonry in prison. He's not out yet or I'd have him on the broom. Again, Thanks for your advice.
#10
07-08-16, 02:19 PM
I'm not aware of bleach harming concrete but I suppose it could as it can harm wood, vinyl and other substrates BUT as long as you use common sense, don't use the bleach straight out of the jug and rinse it well - shouldn't be a problem.
