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Mold/ mildew on cedar sidewall shingles

745sarachal's picture

We installed Western Red Cedar sidewall shingles on the exterior of our house about 10 years ago.  We bought these shingles from a factory in British Columbia and they were "floated" in an oil based stain from a well known manufacturer.  (Not mentioning the companies involved as I am not sure if that is allowed.)    We installed them (it's large house and it took us about one year to finish the project) and we recoated them with the same oil based stain after completing the installation.  Over the past year, these shingles have started growing mold and or mildew, and not on just the Northern side, but on every exposure of our house.  They look terrible.  We have several Oak trees in our yard but we live in California so there isn't a humidity problem.  I was recently told that oil based stains provide great food for mold/mildew.  Has anyone had this same experience?  How do we remove the mold/mildew?  How do we remove the stain?  If we use a pressure washer, it sounds like we need to use the lowest pressure possible and a "fan" tip.  Does anyone know if this willl actually work to get rid of the mold/mildew and stain?   Once we have them all clean (if that is even possible) what do we use to stain them?  This is going to be a very time consuming project and we don't want to have this same problem again.  We are wondering if we would be better off removing all the shingles and starting over.  Although this would be costly, it might be faster than scrubbing down the entire house by hand.  Thank you.

MOld will grow on anything, (post #214661, reply #1 of 2)

MOld will grow on anything, I've seen plenty of windows covered with green mold. Actually the mold grows on the dust that accumulates but that's a moot point if it happens to you. I'd hit it with a pump sprayer of bleach with a little dish detergent mixed in to make it stick then pressure wash from the top down. Keep the tip away from the wall so you don't cut into the shingles and the mold should come right off.

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.